Last month, ProPublica and On The Media released We Don't Talk About Leonard, a new podcast that explores the web of money, influence, and power behind the conservative takeover of America's courts, and the man at the center of it all, Leonard Leo. Today, we're going to discuss Leo's path to power, how he wields his influence, and his ambitions beyond the court. We'll also answer your questions, which you can send us by clicking on the Q&A icon at the bottom of your Zoom screen. And now, allow me to introduce today's speakers. Joining us is Andrea Bernstein, Kate Shaw, and Julia Longoria. Andrea Bernstein is the Peabody and DuPont Columbia Award-winning co-host of We Don't Talk About Leonard. She previously co-hosted the ProPublica and WNYC podcast, Trump Inc., as well as Pineapple Street Studios, Will Be Wild. She currently covers Trump legal matters for NPR and is the author of The New York Times bestseller, American Oligarchs, The Kushners, The Trumps, and The Marriage of Money and Power. Kate Shaw is a professor of law at Cardozo Law School, a contributing opinion writer with The New York Times, and co-host of Strix Grootany, a podcast about the Supreme Court and the legal culture that surrounds it. Julia Longoria is currently a freelance radio journalist. Most recently, she was the host and managing editor of More Perfect, WNYC's show about the Supreme Court. She was also the co-creator and host of the Atlantic magazine's flagship show, The Experiment. She began in public radio newsrooms in New York and her hometown, Miami, and her work has appeared on NPR and The New York Times. Thank you all for being here. I'll let Julia take it from here. Hello, everyone.  I met Andrea when I was a baby reporter at WNYC, so I was a little starstruck when she asked me to be the master of ceremonies here. And Kate Shaw, the team at More Perfect, are huge followers of your work, so I'm so thrilled to have you here. We are here today to talk about a very powerful man that people do not talk about as the ProPublica podcast title says. And with me today are two reporters who have talked about him. They've paid attention to him for a long time and uncovered the influence he has had on our third branch of government. I, like a lot of us here, I imagine, was very cool in high school. And I was on my high school's constitution team. And I think like a lot of Americans, I was taught to really venerate the courts. The Supreme Court was supposed to be the protector of our liberties above the fray of politics. And maybe it's that mythology that has made the institution vulnerable to behind-the-scenes influence. So, let's dive in. Andrea, I want to start with you. Can you take me back to the very first time you heard the name Leonard Leo? Oh, boy. Interesting question. I feel like probably I heard about Leo in conjunction with the Supreme Court. And his work, or the list that he gave to Ben candidate Donald Trump, which I really don't think we learned about that list until the end of the campaign and when Trump became president, that here was somebody who worked for the Federalist Society who was giving Trump a list of justices. And it sort of crossed my radar as well. That's a lot of power for one man. However, when I learned about it, I was working on the podcast Trump Inc. and very much focused on Trump's business and the relationships and conflict between the Trump business and the Trump presidency. After the Trump presidency, I worked on another podcast called Will Be Wild, which was about the insurrection. And then this Leo podcast, in some ways, I mean it's much broader than Trump, but we went back and sort of looked at Leo's relationship with Trump and how he got to be the person who gave Trump these lists of Supreme Court justices. And one of the people, one of the scholars that we spoke to when we were reporting the story was Amanda Hollis-Brusky, who wrote a book about the Federalist Society and teaches it at Pomona College. And she said to us something that really sort of stuck in my mind very early on in Leo reporting. And she said, giving Leonard Leo control over who would be his Supreme Court nominees was the only promise that Trump ever kept. And I thought to myself, wow, that is true. So that was the beginning. And then everything sort of spooled out from there. And Kate, my understanding is you've been watching Leo longer than that. You had your eye on him. Is that right? When did he first get on your radar? I have and yet I don't recall the first time I heard of Leonard Leo. I've been trying to think of it. I actually took constitutional law many, many years ago with Steve Calabrese, one of the founders of the Federalist Society, with whom I've remained very close over the years. And he founded the Yale chapter. He's usually credited as one of the founders. So I don't think I heard talk of Leo back in my law school days. But I kind of think I'm going to tell a brief story, if you'll indulge me, which is that when I was clerked for Justice Stevens in the 07 to 08 term and 2007 was the 25th anniversary of the Federalist Society through a big gala union station, which kind of gets transformed into this gorgeous event space. And the Supreme Court has just stopped the road from Union Station. And at some point, all of the law clerks clerking that year got an email inviting us to the 25th anniversary gala. And my co-clerks and I said, we should go. And so we sent an email to the Thomas clerk who had forwarded the invitation. And she said, are you serious? And we said, well, was the invitation serious? And she said, sure, if you want to come. So anyway, we came. And it was a fascinating and revelatory evening, 25 years in and this extraordinarily powerful institution that still in many ways clearly conceived of itself as a set of insurgent outsiders, despite the presence of multiple Supreme Court justices, despite a recorded vo message from then President George W. Bush. It was really sort of a star studded affair. And yet that was the tenor of the event. And I feel like he must have been there. And yet I cannot confirm that fact. But certainly somewhere in my sort of years as a young lawyer, I heard the name as someone who is an important player in federal society circles. And certainly so for about almost five years, I've co-hosted the Strix scrutiny podcast with Leah Lippman and Melissa Murray. And for as long as we've had the podcast, we've spoken about Leonard, but definitely not as much as Andrea and her colleagues who have done just incredible reporting both in print and in the WNYC collaboration. So I've learned a ton from their work. But certainly I had a little bit of knowledge going in. That's so. I would need to fact check this, but I am pretty sure Leonard Leo not only was there, but spoke. He spoke at most of the annual. I think that's probably right. But I am a single source. And it's a hazy recollection. But I would love to know if that was true, because then I could actually confirm that's the first time I at least saw him in the flesh. Maybe we can check it in the course of this hour. But I mean, I think that Julia was one of the things that I think really motivated us was that here was somebody who made such a faint impression, even on people who were incredibly interested in what he was doing or would have been had they known. And that was one of the reasons why we wanted to do this podcast and the long-form article for ProPublica was to really bring it all out. Who is this person who has so immensely influenced all of us? I mean, if you take the Supreme Court, we always say, well, he didn't just. And then we have to put just in air quotes, because just helping to confirm or nominate six members of the Supreme Court is quite something for one human being. But then the series that we did is how he's done so much more than that. Yeah. And I want to rewind to the beginning of Leonard Leo's career, because it's kind of striking that someone who's never held office has had such an outsized influence on politics, on our courts. ProPublica published a high school photo of him that really struck me that he and his wife were apparently voted most likely to succeed. And they are pictured with these huge glasses and piles of money. And he certainly has been successful at reaching his goals. I mean, Kate, can you talk a little bit about how he began? How did he start to get so much power without holding office? Kate, you're muted, I think. Sorry about that. I don't know how that happened. I want to defer to Andrea on that, who I think has a much better sense of origin and trajectory. But I do think that there are individuals for whom the spotlight holds no appeal. And my sense has always been that he very early on had this incredible insight, which is that sometimes, whether it's that you can redirect the energy in ways that allow you to amplify your impact if actually self-promotion is not consuming any of your attention or time, whether it's that or whether it's a set of interpersonal skills, which I think are a very unique set. And those, I think, I have only really learned about from the reporting that Andrea and her colleagues have done. But that there was sort of a fire within him that I think everybody was able to perceive. That was a deep commitment to a set of deeply conservative legal principles and an ability to identify individuals, fellow travelers, and really cultivate relationships and help shape the trajectories of their careers and thus create this network of relationships and loyalty that was able to, over this is a very long term a project of many decades, I think it really sort of speaks to kind of long-term vision and patience in a way that you sort of have to admire whatever you think of the kind of substantive visions and values. So those are my impressions. But I really have to defer to Andrea in terms of actually having more sort of direct insights into how he was able to do all of it. So I have a story about that high school yearbook photo. But before I say that, I think that what Kate is saying is really essential because unlike, say, the Koch brothers or George Soros. Like, I mean, I used to cover, I covered the 2016 presidential campaign and Bernie Sanders would always have a line about the Koch brothers and like the whole crowd would say boo. And Trump similarly talks about George Soros and people say boo or they sort of metaphorically say boo on social media. But here's literally, it was not a wealthy person. He didn't come from wealth. The house that he grew up in was so modest.  But the street was sort of not fancy. The houses were closed together, the houses were small and that is where he grew up. But he understood very early on that understanding how to raise money was a key to success. And I had gone down to, I had been trying to find his high school yearbook just sort of like basic kind of investigative reporter 101. Like let's try to find out what it was like and try to track it down through the high school. And I had called the library and I said, well, do you have it? And they said, we don't have that year. And I thought, okay, well, I'll drive down there anyway. Maybe they'll have something from 19, you know another year that happens to have a picture of him and then I went there and I said, do you have 1983? And they said, yes, and they brought it out and I start paging through it.   And he has, you know, a blazer and vest and he looks very serious and he's the president of his class and then I'm flipping the pages and there is this most likely to succeed picture with the person who was the vice president of the class, now his wife, Sally Leo, then Sally Schroeder and they are the most voted, most likely to succeed with, as you say, this pile of money. And one of the interesting things is that, you know, Leo wouldn't do an interview with us because, I mean, well, no, let me rephrase that. He said, yes, I will do an interview but you can't ask me about my relationships with Supreme Court justices or my financial arrangements. So we declined, but then he did engage with us. He did answer our written questions and he answered that written question saying that he was, in high school, he was nicknamed money bags kid because he raised so much money for the senior class events that there was money left over to go back to the high school. And that was the beginning, I think, for Leo of understanding that raising money could be a route to power. And he got to start, my understanding from, you know, your reporting is that he got to start at the Federalist Society, which is kind of a hard organization to wrap your mind around, like, you know, more perfected some reporting at one of the Federalist Society meetings. And some members told producer Alyssa Eads, we're just a debate club. So can you talk a little bit about his early involvement in the Federalist Society and kind of how that started the whole project? Well, I would love to hear from Kate a little bit about this debate club thing, because I do think it's like, I mean, I think at one point it was true, but Kate, since you studied with Steve Calabrese, he was one of the founders, maybe you have some- By the way, he taught us a freshman seminar that I went to, so he's gotten around. Well, I don't know, you could probably speak to this as well. So maybe I'll say just to say something about Steve at the outset. I do think that he played it unbelievably straight in his, so as a con law professor, he did, I think, absolutely no sort of inculcation of conservative user values in the classroom. And I'm just great credit. I don't know about your experience if it's an undergrad. But it, but so I do think that, you know, even founders of the Federalist Society, I think that sort of classroom component should be divided out from what the mission of the organization more broadly was, was and is. But, you know, folks like Amanda Hollis-Brusky are, I think the real experts on this, Steve, both Amanda and Steve Tellus have wonderful books. The Rise of the Conservative Legal Movement is Tellus' book and Ideas with Consequences is Hollis-Brusky's book. I think both wonderful. You know, there are, it's a longer story than we could sort of tell here. I think you have a few different factions of both sort of anti-government, anti-regulatory lawyers. You have actual social conservatives. You have sort of a few different strains that fuse together with different sources of funding for different aspects of the project. But I think maybe broadly speaking, I think it's fair to describe the federal society and its inception in the early 1980s. The account given by a lot of members is that it's a reaction to the sort of liberalism of the Warren court in the 1950s and 1960s and to degree the kind of early Berger court and its sex equality jurisprudence and of course, you know, contraception and abortion in the late 1960s and into the 1970s. And that this kind of sense that the sort of institutions of law were captured by liberals and that conservatives needed to mount some sort of response to that. And that Supreme Court was a liberal institution and the constitution was being interpreted for the first time, in my view, in ways consistent with the equality promises of the 14th Amendment and in, you know, robust readings of the criminal procedure protections in, you know, the Bill of Rights and, you know, a correct sort of broad reading of the First Amendment, but one that was sensitive to dynamics of sort of power and money. And so, you know, there are, I think, new for sure, to my mind, correct, but new interpretations of many constitutional provisions. And I think for many conservatives in the law and that included really prominent folks in the Reagan administration, in particular the Justice Department under Ed Meese. And that included, you know, later Supreme Court justices like John Roberts and Sam Alito and, you know, Thomas, although he wasn't in the Justice Department, he's in the Reagan administration, EEOC. That was the sort of the kind of like initial, like animating force that they were responding to. I think that story gets told in both of the books I just mentioned. And then I think it's a kind of long and complex story in which you have a number of, you have both government actors who are really important players, a lot of individuals inside, you know, academic institutions and then funding that comes from various sources but is small in the beginning and then becomes not at all small. I think, and I guess I don't know exactly at what moments in time, Leo is the sort of driver of the sort of funding, but it becomes an incredibly powerful network that is, again, in its inception, sort of about responding to and correcting what is perceived as this kind of liberal overreach of the sort of institutions of law and the Supreme Court in particular and seeks to sort of offer a blueprint for reorienting in a correct way, a vision of the Constitution and of our law that, you know, protects corporate interests against regulation that does not read into the Constitution rights that are not explicitly written into it, that, you know, maybe is what is described as, you know, colorblind that will not permit race conscious measures by government, even those designed to ameliorate histories of subordination and discrimination or to advance values like equity and diversity.  I think there's a through line to a lot of them, but I think they come in a couple of different buckets. And so, you know, it becomes this incredibly powerful institution with chapters in law schools and cities across the country. And to the debate society piece, and I'll just say maybe one word and I'll stop talking. I think that it has long been the case that the Federal Society has described itself that way. And I don't think it's false. It's just wildly incomplete. And I do think that FedSoc chapters historically put on often genuinely rich and illuminating debates in law schools and elsewhere on pressing legal questions. And I think that I haven't in years, but I once upon a time did occasionally participate in Federal Society debates. I definitely attended a lot as a law student and to a degree as a young lawyer. And I think that the part of the reason it's successful is that they partly because of funding, you can sort of put on a nice event and feed and, you know, water people well, but also to attract good people and pay airfare and things like that. You have really kind of high level debate about pressing legal questions. And so I think that's part of the way that sort of that's part of the identity that FedSoc sort of puts forward. And I think absent the kind of digging that, again, academics like Amanda and Stephen also investigative reporters like Andrea have done that might be the only thing that individuals really knew about the Federal Society, I guess, but for the famous Trump list. And that I think is what sort of catapulted into public awareness. The existence of this network and its unbelievable power and reach. Yeah, and I want to get into Andrea's reporting around Leo's influence beyond the Federal Society. So, you know, you uncovered just to name a few of the things that the role he's played in sort of setting up a pipeline for not only Supreme Court justices, but Supreme Court cases helping to put leaders and state leaders in place at a state level. Sorry, say that four times fast. Who would bring, you know, who would be bringing cases to the court and sort of move along a conservative agenda. So could you rewind to the beginning of your reporting Andrea? Like what were your questions? How did you go about answering them and what were some of the obstacles? Yeah, so when we started this project by we, I mean, so Ilya Maritz and I, Ilya and I have collaborated on a number of podcasts. We joined the ProPublica Democracy Team just a little bit after Andy Kroll had broken the story of Leonard Leo getting $1.6 billion to control in dark money from this electronics magnet named Berryside and it's kind of obscure person. It was at the time, the largest dark money contribution in American history. And we began asking ourselves, well, what does he want to do with $1.6 billion? So that was the origin. And we began sort of, you know, ask around and sort of look at the different things that had been written and the money trails. And I would say one of the early insights that we have that we could see was this, that Leonard Leo was the vice president of the Federalist Society. Even though there was a president, Leonard Leo sort of ran the organization in many ways, raised the money and not only worked on this sort of conservative legal nonprofit but cultivated relationships with presidents. So it became the outside advisor for George W. Bush. One Bush advisor described us, you know, as like the person on the PTA who comes to every meeting. So because they come to every meeting, they get the power. And this was how Leonard Leo cultivated access. Once he had access to President George W. Bush, he began suggesting Supreme Court nominees and he had also worked on the nomination of Clarence Thomas. So he was already connected to the U.S. Supreme Court very early on his career. So one of our earliest insights was that Leo went beyond this nonprofit world. He got access to Supreme Court justices and presidents and then in Washington sort of used that currency to raise money that he would plow back into the Federalist Society and also into an immensely influential and little known organization which was called initially the Judicial Confirmation Network. And this was even before Citizens United, a group that was spending money on first the Supreme Court nominations of Alito and Roberts but then quite quickly on something that we really didn't understand at all until he began to do this reporting which was the State Supreme Court Justice Races. And Leo got way down into the weeds. I mean, take one example, in Missouri, Leo and the Federalist Society, but Leo in particular wanted to change the way justices were selected. Going back to the thing that Kate was talking about, they felt like the nonpartisan plan that Missouri had was favoring centrist and left wing justices. So they wanted to get rid of that system and replace it with elections and or a way to have more direct political control. So they went right into Missouri and the strategy was that there was a new justice that was supposed to be selected and Leo started threatening the governor, basically saying through his chief of staff that if you select this person that we don't like, the fury of the conservative movement will come down on you like you've never seen before. And that's a paraphrase, but it's pretty close to the actual wording that Leo had. And one of the interesting things is I made calls and sent emails to people in Missouri for months. I spoke to the person who was the chief justice at the time this was happening. And I said, well, what about Leonard Leo or the Federalist Society? Were they involved? Maybe a little bit, I'm not sure. And then I came across these emails and that was sort of the pattern that repeated. But one of the things that Leo understood early on was that so much power lay in state courts because they could not only, I mean, it's not only a worse, I think 90 plus percent of the litigation is decided in the country, but they could send decisions up to the US Supreme Court. And that became the machine that Leo was working on was to not only get the justices, but to get the outcomes by working on state Supreme Court justices, working on supporting specific candidates for attorney general who can get cases off into the Supreme Court more quickly, supporting conservative law firms. So there was a whole machine to produce outcomes like say the Dobs decision of 2022, which Leo is very, very concerned with, but a whole bunch of other decisions that Kate and company have talked about a great deal on strict scrutiny having to do with the administrative state, climate law, voting rights, all of these things have gone up through the machine that Leo has built to influence the way the Supreme Court decides cases. Yeah, I'm a little bit more, because I just find it really remarkable that you've been able to uncover these emails and these kinds of relationships given how, what lengths Leo seems to have gone to like keep this out of the public eye, like what were some of the obstacles you hit, like how did you get people to talk to you? And yeah. Well, one of the things was that, I mean, one of the reasons why we didn't, why we called the podcast, we don't talk about Leo is, we put out, I mean, Leo is a public person. He was executive vice president of the Federalist Society and worked with many people. He had worked with law professors. He had worked with scholars.  We said, we'd like to talk about Leonard Leo.  We were like, well, we wanna talk to people who think highly of Mr. Leo because we wanna understand the full person. And it was very hard. And there were people who told us who were Leo associates, no one will talk to you because of his $1.6 billion and they're afraid of cutting off access or they're afraid that there might be some political repercussion if they wanna run for office. So people were very, very reluctant. I mean, at the end of the day, we were sort of joking because I think we settled on the title, but then people did talk to us for the podcast, his high school classmate, one of the co-founders of the Federalist Society, many former state Supreme Court justices spoke to us, some of them on tape, on the record and his neighbors. And so, but overall, I mean, I've reported on some people that don't wanna be reported on, the Trumps, the Kushners, I've run into a lot of obstacles, but I would say this was one of the tightest, hardest circles to penetrate. And also the thing that Kate was talking about earlier, the way he sort of glanced across the radar without making an impression. So it became, that was one of the hard things of really sort of like, he was somebody who, as Kate was talking about, sort of embraced being in the background, which is very unusual for Washington. And that meant that it was, hard to pull in those moments where he really made an impression. I feel like, can I jump in with a quick question, which is that I don't, I promise I'm not trying to take the moderator mic. I love it, more collaboration. Okay, thanks. I'll ask you back. So. Okay, great, great. It was just chaos is gonna ensue. No, but this is a question that I wanted to ask you, Andrew, when we had you one strict scrutiny, but we ran out of time and so I didn't get to, but I was curious if you were surprised at his willingness to participate at all. So you said he was willing to actually sit for an interview, although proposed parameters that you guys were not comfortable with, but then did answer written questions like really did. And I actually found that somewhat surprising. So I was curious if you expected a response at all and either way kind of to what do you attribute his willingness to participate in some form with your reporting? So we honestly didn't know. I mean, he had sat for interviews before he sat for an interview with the Washington Post, for example, there were a spate of interviews sort of mid Trump administration after Gorsuch, maybe after Kavanaugh, where he did sit down and talk to people about his role in pushing for these conservative justices who are now in the court, maybe also after Barrett, although there was so little time between that and the election that I couldn't say for sure. So he is somebody who's spoken publicly and we just didn't know if he would want to talk to us after the whole thing happened with the interview and we were like, you can decline to answer, but we can't put a parameter on what we're going to ask. I wasn't sure, but then very, very deeply, we sent out maybe 20 pages of sort of factual questions to fact check as well as just a number of reporting questions. And he engaged in a number of them and he confirmed many things. I mean, for example, just to take one, the judicial crisis network, Leo is not a part of it in any formal way. So investigative journalists over the years have like jumped through hoops to describe his relationships. They were on the same hallway, they were founded at a dinner that he hosted with Justice Scalia and he invited Robin Arkley who is a sort of mortgage magnate, if you will, and others to this dinner who would give money. But we said to Leo, you founded and supported the judicial crisis network and he's confirmed it. And that was like, okay, so all of these sort of hoops and things that we had prepared to do, we don't have to say because Leo has confirmed it. And some of that, I mean, one of the things, and maybe we're going to sort of talk to this now, but one of the things that he has made him so powerful is that he goes to these federal society meetings at law school and he meets people and he mentors them and he calls them and he makes calls on their behalf and he places them in jobs. And one of the people who had worked with him told me that once people got to, once he nominated them for judge or justice, they were people he'd known for 20 years. So we gave him a list of people that we had been, we understood that he had mentored, one of them was Lawrence Van Dyke. There was a number of other people, one of them was Eileen Cannon and he confirmed that he had Eileen Cannon, it was the Trump, the Florida, the Mar-a-Lago documents case judge and he confirmed that he had mentored these people. So we didn't know. So I don't know how the sort of answer to were we surprised by something that we didn't know, but we didn't know what to expect. But I feel like it certainly made the portrait more complete and I think it speaks to the fact that Leo, he's an image man. He runs a company called CRC Advisors, which advises people on public relations strategy and obviously cares about his own image and how it just shaped. So much of what you're talking about, the way he's sort of been successful at having influence has been building these networks of people, he knows them from the beginning of their careers and fundraising. So nothing we've talked about is illegal. I'm more perfect, we kind of joke that like everyone in the legal profession seems to be on the same group chat, like everyone kind of knows each other. And I wonder like an audience member actually asked like, should Leonard Leo's rise be seen as a scandal or is it just a blueprint for success? Do either of you want to answer that audience question? I'm interested in Kate, what you think about that? I think when Joseph Scalia passed away, Jamal Green, a professor at Columbia who's a wonderful scholar had a op-ed in the times that I can't remember that the headline said something like he was my hero, not that I believed in anything he thought about the Constitution but he was unbelievably effective and successful in convincing now a majority of the courts and the lower courts and the public writ large of the correctness of this method of constitutional interpretation, originalism and textualism, these are sort of the methods with which he's closely associated. Although I think both have evolved in ways that I'm not sure Justice Scalia could even have predicted or anticipated or even maybe would have wanted. And you have to give it to him that he was an unbelievably effective spokesperson for these methods. And there have not been justices on the left who have been effective communicators about their methods of interpretation in the same way. Now there are all kinds of reasons where that mess is a little bit of field. So I'll come back to Leo, but I think there's a related point to be made which is that I think that it's, I would say there's a combination. I think that there is the left has not had figures like Leonard Leo and I'm not saying that they should, but I think that that is a descriptive kind of observation. But I think that to the kind of questions where you said nothing that he is engaging in is illegal. And I think that's from what we know that seems right. Like there are certainly norms being violated. And I think that one of the sort of big important lessons of the last sort of six, eight years of our national life is how much of our sort of collective public lives. And that includes sort of both worlds of both law and politics have been governed by even in the law more norms than a hard law or at least a lot governed by norms in addition to hard law. And so I think things like lobbying and advocacy of elected officials in terms of the appointments that they will make to the state bench or the federal bench are longstanding practices and that administrations of both parties and groups both left and right have long engaged in, but that there have also long been kind of boundaries and lines respected and observed. So even in sort of settings in states where that voters have decided and state constitutions have decided to select judges in a way that is different than the federal system and to create judges where you run for office, you're not insulated the way federal judges are at least sort of structurally and formally from direct political accountability and feedback. Like they serve for life, things like that, states mostly make different choices. So even where some politics and law have been commingled and things like judicial selection, there have just been boundaries observed and maintained in terms of the kinds of lobbying, the kinds of sort of self-conscious efforts say to get judges with particular ideological profiles considered and you might say, well, a lot of that is just sort of etiquette or sort of circumvention. And in some ways, like what this did was the kind of efforts to sort of directly appeal to elected officials to sort of seek to have more conservative judges placed on the state bench. And also to seek, Andrew didn't mention, but one of the, I think sort of many wonderful things about the reporting is what it sort of, the light that it sheds on the one obscure office of the state solicitor general, this really, really important office inside states, inside state attorney general's offices that I think as, I'll garble this a little bit, but I think as Andrew said something like once upon a time, these were these offices that defended the state and did some financial protection of consumers, things like that. And now we're doing unbelievably high impact national stakes kinds of litigation that involve everything from sort of climate change to student debt, every major presidential policy seems to be subject to a very swift challenge typically by the state of Texas and often with other red states in tow. And that is a pretty new development and closely linked to the rise of the office of state solicitor general. And so there too, deliberately targeting AGs and seeking to convince them to appoint sort of young, highly, highly ideological lawyers in order both to allow those lawyers to use the office to promote a legal policy agenda, sorry, but the siren outside, but also to kind of burnish the credentials of those young lawyers in order then to help catapult them to these positions of sort of judicial office, federal appellate bench, things like that. That's not in any way legal, but those were just things that were not done because there were norms against doing them for a very long time. And so I think that if you sort of believe in institutions and norms as important institutions, and I do, I think that you don't necessarily want sort of a symmetrical effort on the part of, the legal left to respond. And on the other hand, sort of just a decision to kind of unilaterally fail to utilize tools that actually are now on the table and are important also seems really problematic and designed to lead to more kind of like asymmetry and a distortion of both like the kind of personnel on the bench and substantive legal outcomes. There's obviously a close connection between those two. So as my long answer probably reflects, I think I'm conflicted. There's much to admire. I don't think that I at least can't really deny that. And yet I don't think that it's conduct or a path that I would want to see emulated either. I just, you know, would, well, just a quick asterisk to that. Leo is being investigated by the DC Attorney General regarding a complaint about inappropriate sort of use of nonprofits. I mean, one of the things we haven't touched on but we talk about in our more in-depth in the article but also in the podcast series a little bit is about the way that Leo created a network of nonprofits. He's on the board of them or he raises money for them and they give to each other. And it becomes very confusing to sort of follow the money train which I think is another reason why it's very hard to talk about Leonard Leo because, you know, by the time you've explained the money that goes from, you know, JCN to students for life to et cetera, to et cetera, to et cetera. You've, you know, used up all your time especially if you're working in the audio format as we do. So, so, and then many of these nonprofits hire the company that Leonard Leo runs. So there's a question there but I don't think that that's really what people are talking about when they say illegal. I mean, I think what Leo figured out as Kate was just saying is like, you know we have called him like the Robert Moses of illegal infrastructure because he's figured out these mechanisms and places to exert power that nobody else thought of. And for example, one was the, you know all of episode two, much of it is about Lawrence Van Dyke who's now a judge on the Ninth Circuit Court of Appeals in a very powerful position, very, very conservative particularly when it comes to the Second Amendment. He is somebody that Leo nurtured from early on. He was in the Federalist Society at Harvard. You know, we were told by various people who were familiar that Leo and his associates had called around making sure he had a job. He worked as in the Solicitor General's office or as Solicitor General for three different states and is now in the Ninth Circuit. And there's even a bit of a more of a surprise that I'll let people listen to episode two to hear what that is, but you know his sort of career prospects are even brighter than that. And this is the exact way that Leo sort of figured it out. And it takes a long, you have to focus for a long time. You have to focus for 20, 25 years if you're starting with law school and you know, you're looking all the way up to the highest levels of the federal judiciary as Leonard Leo is doing. And you know, we've talked about the ways that Leonard Leo has sort of elevated the Solicitor General position, the ways he's kind of influenced who's in power at the state level. But you know, over the past year, our understanding of Supreme Court justices and the norms around the Supreme Court around the Supreme Court have shifted thanks to some dogged reporting from ProPublica. So we found out that there are gifts that some Supreme Court justices are accepting from billionaire mega donors. And that's again, something that's not quite illegal but seems to violate a norm. Andrea, how does Leonard Leo fit into the picture of that arrangement? So he is actually in the picture in one of these trips when he and Clarence Thomas and Harlan Crow, who is a Texas real estate magnate ProPublica reported on a lot. Harlan Crow invited Clarence Thomas up to his mansion on Upper St. Regis Lake in the Adirondack Mountains and there was a picture painted. And Leo is in the picture with Harlan Crow and Clarence Thomas and a couple of other legal associates. In on another trip with the Justice Alito took where there were Paul Singer was there who is a hedge fund magnate and ultimately had an interest in a case that was decided by the Supreme Court. It was a seven to two decision but Alito had voted in his favor. And they all go up to an Alaska fishing trip and our colleagues, Justin, Justin Elliott and Josh Kaplan and Alex Meyer-Jesky discovered that the only link between these people between Paul Singer and Robin Arkley and Alito is Leonard Leo. Leonard Leo is in the middle of it all. Leonard Leo is setting these things up. He is arranging these trips. He even in fact arranged for Paul Singer to get his salmon that he had got from his fishing trip after it wasn't delivered to him. And that I think is something that was central to our understanding that Leo would befriend these very wealthy people who might have an economic interest in Supreme Court decisions. And they would donate money to Leo's causes that would then reinforce the sort of moral conservative the anti-abortion conservatives the ones that were pushing for decisions on religious liberty or on same-sex marriage. And but the money machine sort of was boosted by these encounters so far as we can tell from our reporting. And as these revelations have come out there's been sort of a, I think like an awakening from the public like, wait a second shouldn't this be against the rules?  There is an ethics code for lower court justices but the Supreme Court didn't have one until this week when they finally published one. And Kay, I wanted to get your take on the ethics code. Have you read it? Do you have any initial impressions, reactions? I hate it, I read it, I think it's but I think it's so important and just enormous, enormous credit to the folks of ProPublica and also the times and elsewhere who have done the reporting the dogged reporting that is 100% responsible for the fact that the justices felt enough heat that they put together this woefully insufficient document but the fact of it I think is enormously important. It's been characterized as worse than nothing and I think there is something to that in that the document in a very kind of defensive sort of preamble statement suggests that it is merely codifying the practices the justices have already followed, the rules the justices already adhere to. And I think that in Millheiser at Fox had a great I thought distillation of this aspect of the problem with the document but that is that it can be read essentially to retroactively bless everything that we have seen reported on that Andrea was just talking about because it says the justices already do this but here in order to says the document dispel a misunderstanding that the justices are not in fact bound by any ethical rules or guidelines we've basically put it in writing for you. So that I think is enormously problematic just as sort of a framing device and I also think the substance of it is wildly deficient. So there are even things like affirmative permission provisions for justices to engage in fundraising activities which I think was at least murky previously and here a justice may assist non-profit law related civic charitable education religious or social organizations in planning fundraising activities. Sorry, I'm reading here and maybe listed as an officer or director or trustee, et cetera, et cetera. So there are actually a few places where I think that there is an affirmative blessing given by the court to activities that at the very least the justices many of them believe themselves unable to participate in that of course they don't have to simply because the ethics code says it's not prohibited but there are other places where it seems as though the justices actually are not prohibited from using the prestige of the court or the office just prohibited from knowingly using the prestige of the court or their offices that seems like an important distinction they can simply claim ignorance if in fact they are engaging in activities and others responsible for organizing those activities are trading on the justices positions the physical building of the court things like that. So I think it is an incredibly underwhelming document so much so that I'm actually a little bit surprised that everyone joined them and they like to hang together in something like this that sort of put forth a unified front to the public but I can't imagine all nine of them think that this document goes far enough or does enough and yet I think the fact that they felt the need to do it that they felt the heat that is a testament to how important this reporting is and how important it is that it continues. Is it gonna result in a better document that actually clearly prohibits some of these activities in particular the ones involving accepting gifts? I don't know, but I think that it is a testament to it actually really mattering. I mean, I feel like, I mean, I've read a lot of critiques of it and Julia, I'm really curious to know what you think. I feel like a couple of things. One is that when when propublica started doing our reporting and there were discussions, are their laws broken and are there rules broken? Which is important part of obviously of journalism but when the story came out about Clarence Thomas taking $500,000 vacations like scrambling for a rules violation is not necessary. I think people understand that that is problematic. And I think that's one of the reasons why this reporting cut through is because it's just clear.  And having something written down is not always a solution. So for me, the fact that there is a document is, it's encouraging because it suggests that maybe the court is responsive in some ways to what's going on in the real world. And also there's a framework to begin a conversation.  So I think people who are lawyers sort of see the deficiencies of which I will not disagree there are many but also I feel like, wow, there's a document. That's great. That's a starting point. But Julia, I know that you're the host but I am curious what you think because you've also spent so much time thinking about this court. What do you think about that document? Yeah, I think I feel similarly in that it's nice to at least get some kind of response. I think in the initial days after the reports came out the silence and the lack of response at all it seemed like was pretty discouraging. So it's nice to get a response. But yeah, I mean, I feel similarly to Kate in that even from the, they could have just adopted what the federal judges have, right? As far as their ethics code, but like the little detail that I found really amusing is like the federal judge ethics code says like justices shall not. And this code says justices should not which is already softer. It feels like that seems like a small like semantic thing that you could have just copy pasted. But anyway, yeah, it is, I hope it's the beginning of a conversation like you say, Andrea. We are running out of time. So I wanna get a couple of audience questions in. A lot of audience members have been asking about Leonard Leo's Catholic background and how that kind of plays into his goals and his sort of outlook in his political project. Do one of you wanna take that, Kate? You wanna take that? Sure, I don't know. I can't really pretend to speak to it. I presume that his sort of pro-life views seem to have been forged from a very young age. And I am sure that Catholicism played a role in that. And I think that that maybe there are other, I guess I don't know where he is on things like the death penalty, honestly. And sort of, so I presume that that is an important through line. And I think it was a site of sort of bonding and solidarity with like Justice Scalia and other Catholics on the court. But that's probably the only, I am sure it has played a central role, but I don't really have anything else to say about it. Yeah, I mean, I think I would just, I mean, I would refer people especially to the ProPublica article about Leonard Leo because we do dive into this in depth and we ask him about it and he addresses it. It is a fundamental part of who he is. And he gave a speech that we quote at the very beginning of the podcast to the Catholic Information Center in Washington DC, which is sort of a meeting ground for powerful Catholics. He gave a speech in just about a year ago where he really spoke of feeling aggrieved, which was extraordinary to me because he'd won dobs. He had six people on the US Supreme Court. He had $1.6 billion to spend, but he spoke in the language of we are losing and it was a very sort of religious interpretation. So I will refer people to that. I mean, I do think it, and he's a devout Catholic, he goes to mass maybe every day of the week and talks about how his faith really fundamentally influenced where he went. And all of the justices that he supported are now Catholics. And there are, what's seven, right? Seven of the nine, so. Right. And I think we have time for one more question. So I'll throw it to the both of you. A reader wrote in asking what Leo's end game is. What do you think his end game is? I wanna give Andrew the last word on this and I do think that's a good segue to the sort of Taneo kind of federal society for everything. If that's something the audience would be interested in hearing about, I think it's endlessly fascinating. I will talk about Taneo and the other things he's working on, but I'm wondering, Kate, do you have an answer to that? What is the end game is? I don't, clearly I think the fact that there is this sort of sentiment of aggrievedness that is still on display makes quite clear to me that he does not believe his work to be done. And so there is certainly another end game control of the US Supreme Court, which is quite an accomplishment is not enough. And so there is certainly more and maybe more inside the law, but definitely expanding the reach outside of the law is on the agenda. Yeah, I mean, I think that Taneo is a group, the Taneo network is a group that Leo recently took over that we have characterized as a federal society for everything. Leo in a promotional video says, I've been successful in the conservative legal movement and I wanna bring that to all of culture. So Hollywood media, education, really sort of infusing it with his values. There are some very concrete things that organizations that he has supported are working on. One of them is called the honest elections project, which has backed many efforts to, for example, limit mail-in balding, limit the franchise in other ways. And I think also we're watching closely to see how he maneuvers the 2024 election. It is obviously, I mean, in the Trump administration, he not only recommended justices, he recommended general councils, he recommended DOJ personnel, he recommended cabinet secretaries. And we are watching for signs of how that will go in a potential second Trump administration. How would he try to influence staffing? Should that come about? How are they preparing? And I think that is something that must be very much on his mind, the sort of how does he keep it going? I mean, one of the things about these court structures is you have to keep it going. And we're watching that closely. So I don't know if that's an end game, but it's continuing to expand the influence that he's had in the ways that he has. And I hope that people will, we have more of that in the podcast.  If you just put, we don't talk about Leonard in your podcast search engine, you will find it. Great. Well, that's a perfect place for us to end. I wanna thank all of our speakers, Andrea, Kate, and Julia for this illuminating conversation. And to all of you listeners, thanks so much for tuning in. We hope to catch you next time. Thanks again. Have a good night. Thank you, everyone. Thank you.


Welcome to this lecture on field programmable logic arrays, gate arrays in the course digital system design with PLDs and FPGAs. In the last lecture we have looked at the clock tree essentially some basic related to the clock tree why the clock trees are special clock trees are required. And we have analyzed the basic timing of data path and sequential circuit in the presence of skew and then that is the kind of you know setting the background for the clock tree which gives the minimum skew between the end points. And then we have looked at the special resources like DLL, PLL, clock managers and all that and we have started the various method of configuring or programming the FPGA. So before continuing with the configuration or programming we will briefly look at the last lectures portion and then we will get on to today's part. In the last lecture we have looked at basically the issue of metastability for a flip flop not to get into metastability the input has to meet the set up and hold time. And for a data path or a register to register path from that requirement we develop the inequality for the minimum clock period and we develop the condition for not violation of the hold time ok. And same thing with the sequential circuit or FSM where the register to register path is between the state registers expressions are same because if you kind of show it explicitly you know separate the source and destination it exactly looks like this. Now what was missing in this analysis was that we assume in all these you know arriving at this expressions we assume that the clock is reaching at the source and the destination at the same time which cannot be true in a chip you know depending on which way the clock flows the destination could be lagging or leading the source in terms of the clock arrival. So that should be taken into consideration when analysing the these expression and that is what we have done and we have set the two conditions or two scenarios where the clock and the data flows in the same direction which is called a min path problem and where the clock and the data flows in opposite direction. And we have looked at the case where the clock and the data are in opposite direction then in that case the source clock is kind of leading or the destination clock is lagging. So the available time for a register to register path is reduced by amount of skew. So t clock – t skew has to accommodate t skew, t comb and t set up. So in a sense the clock period requirement goes up and the frequency comes down. So because of this skew the frequency of operation is coming down in the opposite problem in the min path problem where the source destination is receiving a clock which is a delayed version of the source register with respect to kind of you know as far as skew is concerned. And in this case looks like the register to register path from one clock edge to the next clock edge we are in a better position because you have t clock plus t skew is kind of time available which need to accommodate this path delay ok. So if you add an edge from one edge to the next edge things looks pretty comfortable because that is you know easier on the budget you know if you would have fixed the clock period or something then here is a relaxation on the clock period so which is good in a way. But the real danger as I said is that since the clock is getting skewed maybe this if this the data path is fast then it can violate the whole time because the clock is moving ahead and if the t co and t comb is min then it can violate the whole time. So that is what is shown here t co min plus t co min should be greater than the t skew max and t hold. So if it is not so it can violate and if there is a violation happens kind of reducing the clock frequency is of no use ok. Because in the earlier problem we sorted out suppose we have a clock period which cannot accommodate this kind of skew then we can reduce the clock period. But in a min path problem it is not related to the clock period at all because we are talking about the same edge of the clock ok. So between the same edge of the clock or between the edges which are delayed same edges which are delayed by the skew. So the only way if there is a whole time violation to avoid is increase the combination delay or the logic delay. So in essence clock when somebody is routing the clock in a chip if there is a relative delay between the end points ok wherever it is that is troublesome that can reduce the clock frequency that can create whole time violation. So there need to be a mechanism to kind of route the clock trees such that the relative delays between the end points are minimal. So that like that shows you know with respect to earlier picture we cannot route like this you know that as the clock tree goes it gets you know everything gets delayed because of the loading and from this end to that end the delay is very high. So we cannot have such kind of arbitrary scheme of clock routing. The ideal thing would be that from the clock pad to any end point there should be kind of equal length of the wire and the equal number of buffers. This scheme does not even help even if you insert buffer here, buffer here, buffer here and all to kind of offset the delays you know offset the loading that does not help because the buffer delays add to this skew. So you should have the buffers which are balanced. So it is ideally like in a simplistic way you can put a buffer then branch another buffer and another branch you know from the main route one more branch with the buffer and so on. So that the extension of that is the H clock tree where from the input point you know you go horizontally branch then vertically branch then horizontally branch wherever there is branching then you put a buffer okay. Now that does not mean that you know this is just one end point where a single flip-flop is connected you know there could be some kind of depending on the buffer capacity there could be 20 or 25 or so many depending on the buffer so many flip-flops are there in this branches in the last branches okay. But like if you have order of magnitude increase in the number of flip-flops then you branch vertically you know each one from there you can go different vertical branches and so on okay. And the idea is that if you take from say take this end point and this end point and if you count the number of buffers up to the end point and take the length of the wires it will be identical. So the relative delay is between the edges between the end points will be minimal though from the kind of the input to the output there could be you know skew quite a bit of skew which is not much of a problem if that is a problem then I can introduce a DLL which compensate for that kind of delay okay. So that is what is the DLL is you suppose you have a clock tree which is getting loaded and because of the loading if the clock is delayed and if there is a skew between the input clock and the output clock then the DLL can avoid that because from the output there is a feedback to the input and there will be definitely delay a skew. But how it is compensated is that the t clock minus t skew delay is kind of further added into the tree. So that this edge will come in kind of sync with the next edge okay. So the delay lock loop you know kind of synchronize a edge by further delaying already delayed edge you know that is how it works. Compared to PLL in a PLL essentially the scheme looks similar you know you have the input clock and the feedback clock. But what is done is that the phase is compared and the phase difference is converted into a voltage with a low pass filter and or some equivalent scheme okay and a voltage control oscillator you know synthesize a clock frequency which is not the kind of delayed version of this input clock frequency as in the case of DLL. But in a PLL a new clock is synthesized okay in phase with the input clock and that has certain advantage in the sense that like if there is a jitter in the input clock in a delay lock loop that will appear as a jitter at the output. Because delay lock loop just delays the clock but in a PLL since it is synthesized and there is a filter which kind of you know filters out the minute jitters and the clock is kind of stable okay it is a new clock it would not have the distortion of the input clock or the jitter of the input clock. So that way PLL is better but then you know that the PLL always act you know with kind of with a range of there is a lock range and there is time to lock and things like that you know at the beginning when you start up the PLL has to get into lock so it takes certain delay for the PLL to come into lock and all that. So that is about the PLL so in the current FPGAs as PLL digital clock manager which is composed of DLL for disqueuing phase shifter frequency multiplication division and this gives phase shift like 90 degree, 180, 270 and all that. There are clock buffers maxes for clocking I know clock switching and that has to be glitchless you know when it has to synchronize the edges. So there will be synchronizing flip flops which synchronize you know 2 clock sources to each other and all this can be connected in the clock path or clock tree path. So that is what we have discussed and this can be all these special resources can be instantiated from the vendor library using the code generator tool. Sometimes synthesis tool will infer from the code. Sometimes you have to write the VHDL attribute along with the code to help the synthesis tool to kind of infer what is going on and to kind of instantiate the correct component. Then the last thing we have looked at was the configuration or programming of FPGA and this the first thing while prototyping the most suitable method is through a synchronous serial port called JTAG which is used for PCB testing, chip testing and all that which is used for FPGA configuration also. So there will be a small dongle connected to PC which can program the FPGA and then there is a serial mode where the FPGA clock a serial prompt and get the data and programs it. Slave serial exactly like master serial where in the slave serial FPGA expect the clock as input and the data in synchrony with the clock normally this works in conjunction with the master serial for a kind of chained programming of the FPGA. And the select map is a byte wide or kind of programming 8 or 16 bit usually when there is a microprocessor through a parallel bus FPGA can be programmed and the configuration bit stream can be stored in the memories of the processor ok wherever it is located maybe in a flash on the board and from there along with the firmware it can be stored and at the start up the CPU can program the FPGA. So this shows a master I mean serial configuration where one FPGA is a master and another FPGA is a slave which is configured by some mode pin 3 mode pins are there in the current FPGA there are only 2 mode pins and see this is in the master mode and this is in the slave mode and you can see there is a serial prompt the clock for the serial prompt is given by the master FPGA. Also the slave FPGA get the clock from the master and the data from the serial prompt is connected to the data input of the master FPGA and there is a data output of the master FPGA which is connected to the data input of the second slave FPGA. Now if you have a third FPGA what you can do is that the data out of the this serial port can be connected to the data in of the third FPGA and so on and you can combine all the bit stream of all the FPGAs and store in the this particular prompt at the beginning what happens is that the power on the FPGA start programming and or if there is a program pin is there if the program pin is made low and you know if you kind of apply a negative you know zero pulse then it starts programming any time. One issue is that at the beginning these FPGAs to clear their configuration memory ok because it could be not a power on programming it could be a reprogramming of the FPGA while the power is on. So all the program memory configuration memory has to be cleared and depending on the FPGA type and the size it will take variable time. So the question is that how do each FPGA knows that the other is completed the initialization. So there is a init pin which is an open drain output which is also sampled internally. So it is an IO pin which is open drain and which is pulled up. So it is like it is forming a wired and ok if everything is high this will be high if one of them is low which is pulled low ok that is the state of this kind of wired and connection. And what happens is that suppose if the master clears the configuration memory and it has come out then it will drive the init output high. So but if this slave is still in the init mode it will be driving it low because of this pull up resistance this still be in low and that is also input to this particular FPGA and that you know sample that input and if this still is it is low it waits for other FPGAs to finish. So this kind of the init which is an IO pin which is an open drain which forms a wired and helps the init synchronization between the masters and slave. So ultimately everybody initializes every FPGA initializes and in come out of initialized initialization and then the master FPGA you know start getting the data ok. You know it gives the clock it enables the clock and you know you can see that the init pin is connected to the output enable of the prom. So even if the clock is going unless the init goes high this chip is not, chip output is not enabled so the data would not come. So once the init phase is over the FPGA starts clocking and get the data. So the first the master FPGA programs while it is getting program this D out is made one ok. The one is going there so the slave wait for the starting pattern of the configuration since it everything is one it will wait. So the master FPGA configures itself once the configuration is over then the slave FPGAs configuration bit comes and that is bypassed to the D out and the slave gets you know programmed ok and so on. Now if the second slave while the second slave programs that leaves the D out with one and the third slave wait. So one by one the FPGA gets programmed and this is a DUN pin which is a which indicates that the FPGA is kind of finished programming. Now again once again this is an open drain output so which is pulled high so it forms a wired and again unless all the FPGAs DUN pin is high this would not go high. So this is an indication to the rest of the circuitry like you will have some like maybe a CPU which is working in conjunction with the FPGAs. In that case this DUN pin will indicate a CPU saying that FPGAs finished configuring and normal execution can kind of continue. So if there is a CPU it will kind of sample the DUN pin and wait for the FPGA configuration to be over once it is done then it will start you know enabling the normal operation. Or if there is another external circuitry you have to make sure that the DUN pin kind of enables the rest of the circuitry otherwise there will be synchronization problem with the FPGA and the rest of the circuit. Because there is another circuit which gives input to the data input to the FPGA and if FPGA is not configured at those the data will be lost. So this DUN pin has to be sampled by the rest of the circuit and normally we can assume the rest of the circuit is maybe a CPU or another programmable logic based circuit whatever it is this has to be taken care while designing. So that shows the kind of very important kind of mechanism to program the FPGA in a chain okay in the multiple or this can be single it does not matter if there is only single FPGA you can forget about this and this works. And nowadays the SPI or SPI is based the PROMs can be used. So the FPGA offers instead of the custom serial port SPI port and the SPI can work with 1 bit data, 2 bit data and 4 bit data. In addition this PROM itself can be programmed through the JTAG port permanently. So not only that while prototyping the FPGA can be programmed through JTAG this SPI PROM not this PROM the SPI type PROM can be programmed through the JTAG port which often when you buy an FPGA board these options will be available. You can program normally a SPI flash will be connected in this fashion to the FPGA so that you can program the FPGA through a JTAG port this flash through an JTAG port. And if you put appropriate the mode pins FPGA can be configured from the flash PROM all that is possible. And that is what is written here all what I have done is kind of elaborated. And the select map scheme where you have a CPU and you have FPGA normally you have a synchronous byte wide or 2 byte wide data you know program the FPGA. And these are the pins you know you have the program chip select write clock and data this is a synchronous bus in it done busy and all that ok. Now the issue with such a bus is that most processor bus are not sometimes synchronous ok like the micro controller bus may not be synchronous. So you may have to kind of translate the bus protocol of the processor to this synchronous protocol. So that can be achieved by a CPLD coming in between to do the protocol translation of the bus and we have discussed the CPLD in the CPLD part of the lectures and we have mentioned that CPLD is good for bus protocol translation. So that is the scenario which is shown here where the CPU has some memory which could be flashed where the firmware is stored. Now the FPGA configuration bit stream can be stored here CPU can access that read it then you know maybe byte wide one byte is read here then the byte is written there again read and write you know such a thing can be done using this kind of scheme. And if possible the CPU can directly write if there is a synchronous port which matches the protocol otherwise you will have to use some kind of parallel port instead of CPLD that can be done. But which can be very slow sometime when you use a parallel port in a CPU because you have to address each port you have to use the port for clocking which can be very slow sometime ok. And that shows the timing like you know every clock edge the data is coming chip select and write bar is low and any time the FPGA is not writing the data it will indicate the busy signal in that case the data has to be kept for one more clock you know. So it is like a kind of extending the bus cycle if the peripheral is slow I am sure that you have studied that such scheme you know normally ready normally not ready kind of system. So this is a kind of normally ready system. So if it is kind of nothing if the FPGA does not require more time then you keep clocking the data every clock cycle if it requires then it indicates it is not ready or it is busy then you extend the bus cycle by adding extra delays. And this is a kind of very simple scheme which can be implemented in a CPLD. So that is what is the kind of crux of FPGA configuration. There are you know current FPGAs are more detailed I will briefly mention it but for vertex these are the main ways of configuring it basically the JTAG the master serial slave serial and I mentioned about SPI port. Then the select map which is byte wide which is 8 bit or 16 bit one thing to remember is that while FPGA is getting configured all the pins will be in tri-state mode. So all the FPGA pins will be in tri-state mode. So the rest of the circuit kind of has to make sure that while you know being configured these pins the status will be tri-stated and it has to be appropriately pulled up or pulled down depending on your the requirement of the rest of the circuit ok. So the rest of the circuit is sampling one of the output of the FPGA which normally in a default state you are assuming it to be 0 but while configuration rest of the circuit comes up before the FPGA configuration then assume that one of the input is 0 if it is tri-stated it can create problem. So it has to be pulled down and once FPGA is configured all the flip flops are reset using an internal reset line which the FPGA enders does not advise you to use as a reset you know.  It is a very kind of high kind of lot of flip flops are connected to it so it is very heavily loaded so it may be a better idea to reset it separately which gives a good drive. So this I just briefly mentioned because there are different you know kind of x centered version of that vertex configuration is available in reset FPGA. So I have taken an example of Spartan 6 it is true of Spartan 6 or kind of vertex 6 or vertex 7 or any of the 7 series FPGAs. So your boundaries can which is a JTAG port which can configure a single device or like we have seen in the serial mode you can chain the multiple devices through the JTAG you know exactly like what we have seen here even in the JTAG there is a TDI pin which take in the data and TDO pin which take out the data. So the TDO pin of an FPGA can be connected to the TDI pin so it can be chained ok. So that is possible so you can in a boundaries can you can have a single device or a chain you can program multiple device. In the master serial you can have chain you know along with the slave you can have a you know chain of devices sometime what is required is that if same configuration has to be applied to all the FPGAs ok. That means all the FPGAs are of the same type and it is configured by the same bit stream it can be connected in parallel and now in the serial mode if you use SPI flash the data bit can be 1 bit, 2 bit or 4 bit there are appropriate pins and similarly for the slave serial you know normally as I said slave serial work along with the master serial for the chain. And in the select map you have 8 bit and 16 bit configuration you can have a single device or you can have a chain of devices in select map you can have slave select map where the clock is here the clock is given by the FPGA but in a slave select map FPGA expect the clock from outside along with the data ok. So it is little more elaborate than the vertex we have studied so I just mentioned so that the information is current whatever I have talked about the lookup tables logic block and all that can be extended to the these kind of new devices. But this is additional so I mentioned that and another issue with the earlier FPGAs were suppose you come out with the proprietary design you put the configuration bit stream in this prompt ok now you send that into the field on a PCB or in a product what can happen is that the power on somebody can capture this data because it is very easy because the clock is coming in synchronous data is coming. So this can be easily kind of reverse engineered now somebody can read the bit stream and reverse engineer the complete system ok because in an FPGA the main thing is in this prompt and that is kind of there is no security on it the bit stream is coming as it is it can be easily read. So it will be worthwhile if it can be kind of protected because mostly this will be some intellectual property of the designer or the company which is doing the design. So what is done in the current FPGAs are that this bit stream can be encrypted using the advance inscription scheme which is called AES using a 256 bit key. Now through the JTAG port this FPGA can be programmed with that key and FPGA can be told no read back that means once it is programmed this key cannot be read back also the configuration can be read back ok otherwise it is possible to read back the configuration for the purpose of verification and so on. So that also can be disabled and then you deploy that in the system that means you program this prompt with the protected bit stream then what is going on this kind of this line is an AES encrypted bit stream and without the knowledge of the key it is very difficult to break the scheme and this can be kind of a key can be very specific to the device that means if a company is making an industry is making say 10,000 devices each 10,000 will have separate keys not the same key. So that way it can be very well protected so that is available in the current FPGAs. So there is an AES encryption with a 256 bit key so the bit stream is encrypted using the bit chain tool with the 256 bit key encryption key is programmed into FPGA through JTAG port and once it is programmed you can configure it for no read back and the configuration also cannot be read back and AES key can be permanently fused like blowing the fuse in FPGA or it can be programmed in an internal SRAM with a battery backed you know with a battery backup which is connected externally. So one can choose those option if you permanently fused you cannot change that AES key so it will be permanently programmed you will be forced to use the same key for all the bit stream you program into to the flash so that way the encryption kind of protect the design. Another option available in the recent current FPGAs are bit stream can be compressed and which is bit older than you know not that this part in 6 even before the FPGAs before has this had this option because there could be a lot of resources which are not used at all used not configured at all so there is lot of kind of redundant information that not being programmed so that information is removed and the configuration bit stream size can come down. So that has two implication one is that you can store it in a lesser memory space and it can be configured very fast the configuration will take lesser time otherwise for a fixed device it will take you know kind of fixed time for the device is larger takes larger time. But even in a larger device if it is not used only 50% is used it might take you know kind of less time than the full FPGA configuration. Another possibility which is available is that suppose I know this addresses suppose you have programmed a configuration here and the feel like if it is programmed in a flash and flash memory and sometimes the flash can get corrupted you know suppose the flash get corrupted then the whole device may not work the flash need to be reprogrammed okay. Nowadays it is possible you know you would have seen that earlier the you know the computers used to update you know through the internet the drivers the software and all that. But now you can see the setup box at your home connected to a TV it can update through the cable you know through the cable the firmware get updated your mobile phone can get updated with the firmware over there. So same thing can happen now the configuration through the internet or wireless network can get you know can get to the device and the device can reprogram itself. So that is a possibility so but still you know in the field if the flash is getting corrupted it will be a good idea if you have a kind of a golden bit stream or a fallback bit stream which may not be the recent one which may be a very old one which is stable okay. So it can happen that you update the configuration over the internet and some corruption has happened then you can fall back on a very stable version which is there from the beginning okay. So that is what is called multi boot and that is what is shown here in this particular slide. So you can have at least one main configuration and one fallback configuration and during the configuration if the CRC error like while the configuration bit stream is read the CRC is calculated if there is any bit corruption CRC will give error in that case it will fall back on the golden configuration or if the sync word detection is timed out that means at the beginning there is a sync word and if that is corrupted and there will be watch talk timer which is waiting for it and if it does not come that times out and in that case it will it can fall back it can fetch the golden configuration from a particular location and that can program the FPGA and can recover from that particular error. And this scheme of multi boot is available only in the SPI based flash prom and the BPA based flash prom okay. So in both it is available it is a very good option if you have a kind of if you are deploying FPGAs in the field you should think of you know the multi boot, encryption and compression and all that which will kind of improve the reliability improve the security all that part okay. Now the current FPGAs in addition to the DLL, PLL block memory and all that you have the DSP slices which allows the designer to implement the DSP algorithms very efficiently and the DSP algorithm normally use fixed point computation 18 bit Mandesa may be used. So there are and you know that in one of the major operation in signal processing algorithm is multiply and accumulate. So which requires a multiplier and an adder okay. So the DSP blocks there is a silence FPGAs DSP blocks give you this particular option you have a pre adder that means there are 18 bit 2s complement pre adder that means you can do signed addition 18 bit in the pre adder and that added output can go to a multiplier which is an 18 by 18 multiplier. So 2 18 bits can be added and that can go to multiplier it can multiply another 18 bit which is coming from a separate port it produces a 36 bit result. Now this can be signed extended to 48 bit and it is followed with a 48 bit 2s complement adder substractor and there are various you know it is not that everything need to be used you can use this multiplier along with the post adder or you can cascade pre adder and post adder bypassing the multiplier. You can take the multiplier result outside 36 bit result. So all kinds of options are available in the DSP slides which really enables one to implement the DSP like say filtering algorithms, the encoders, decoders and so on. All that can be implemented very efficiently in the DSP slices and many a times you just you know use the multiplier operator then if the data size matches then it gets implemented in the DSP slices or it can be instantiated and you can use it. So this is the general architecture you have 4 ports all are kind of pipelined and 2 you can see 2 ports are added 18 plus 18 it give you 18 bit result which is combined with the 18 bit to a multiplier. This output can be taken out or it can be taken to in another adder which is 48 bit. So this is sign extended added with the you know sign extension that output is available. So this helps in implementing the DSP kind of algorithms and this is called DSP48A1 slice in the Spartan 6 and in addition I must mention I have not put it in the slide but I should mention that the current FPGAs allows you to use the lookup table as a shift register. Because the lookup table is normally suppose a foreign boot lookup table you have 16 flip flops inside serving as a location. So that is connected in a chain and is available as a shift register. In this case it is called SRL16 and that can be chained to form SRL32 and even higher 64 bit shift register up to 256 bit in some kind of Spartan 6 slice and that can be you know chained across. So that is you know you get a shift register implementation without using the flip flops of the slice because the number of flip flops in a slice is limited and we have seen in vertex there are only 2 per slice, 4 in a CLB. So if you say implement kind of 16 bit shift register then you will end up using 4 CLBs but using one lookup table in a CLB you can implement a 16 bit shift register. So that is possible to implement and one other important very important thing with respect to FPGAs. So I am kind of discussing all what is remaining you know one problem with the FPGA is that you have designed something in FPGA. You have you know verified you know you have done behavioural simulation, timing simulation everything but the moment you put that design in FPGA for whatever reason if something goes wrong you cannot and if it is an internal signal you cannot kind of debug it. You cannot see what is happening inside okay. So what is done is that the FPGA vendors give you a logic analyzer circuit which is hooked to the JTAG. So now you can instantiate this logic analyzer IP along with your design and the probes of the logic analyzer can be connected to the internal signal. And through the JTAG port there will be a software which is available at the tool side at the PC side and through the JTAG you can capture the waveform of the internal signal and you can analyse it and like logic analyzer you can trigger say it will be kind of crazy because suppose you have some kind of 8 bit data line you want to monitor okay. And your clock is 200 megahertz and in one second there will be kind of 200 mega kind of data passing over the data bus if it is clock that frequency then to analyse that or to store all that there will not be enough memory. So you can if you know that you have a kind of hint saying that what could be going wrong but on a particular data the error happens then you can trigger on that data and capture some data around the trigger point or after the trigger point or before the trigger point. So if you use logic analyzer you would have heard saying that pre trigger post trigger pre trigger 50% and so on that it depends on how much you capture before the trigger how much you capture after the trigger. And the analysis is always offline it is not that you on a trigger point you capture some data and you analyse offline on the PC and try to debug it. So it is a great tool to it is like once you have some complex circuit going to the FPGA to debug this logic analyzers can have to be used and the silencs college chip scope probe and the altera college signal probe and it is very easy now over the years it has become a very nice tool. Only thing is that it occupies because this IP this circuit occupies some kind of space within FPGA. So if you are not really floor planning in the rest of the circuit it can upset the timing performance of your design sometime but then if you properly design floor plan that is not a very serious issue because it does not occupy much space.  And this is the one which is connecting to the JTAG and on the PC side you have a software which on the trigger it captures the data transfer it to the PC and you can analyse and take action you know that is what is the signal probing does. So I am just showing the vertex pins you have the global clock pins which is dedicated which is used which is input to the clock tree. The mode pin for selecting the mode of programming dedicated pins. The C clock which is the serial clock which is can be reused as a user IO program done in it busy the parallel port all that can be used once the programming is done it can be used as kind of this program pin is dedicated but this in it done pin is dedicated but these are can be used as user IO and there is all these you know these are programming pin and there is a JTAG port which is dedicated TMR is the mode select TCK is the T clock TDI is the data input TDO is the data output then you have the internal VCC IO pin VCC the ground and so on. So normally the FPGA this is the scenario you allow clock pins you have some dedicated JTAG port dedicated mode pins and the programming pins some are dedicated most of it is kind of can be once a programming is over can be used by the user okay. So there is one point I want to mention here is something called one hot encoding which is a state machine encoding which is used in FPGAs. This is you see the state machine block diagram we have an excite logic which is decoding the input and the present state and or a two block diagram you know enough of it but what can happen is that we will take an example to kind of you know to put the background for the need of one hot encoding. Suppose you assume a finite state machine with five inputs 18 state and six output. So when you have an 18 states it means that you have you need kind of a binary encoding five flip-flops because it is greater than 16 less than 32 five flip-flops are required and there are five inputs. So if you look at the excite logic and it will get five input and five state variable so there are total 10 input to the excite logic okay. But you know that there are five flip-flops so there will be D4 to D0 each of that may not use all the inputs okay but we assume the worst case assume that all the in some case all the five inputs are used less likely but then let us assume the worst case. So and we assume that so there are 10 input for an excite logic and once again we assume the worst case in the vertex that means we have seen that the five input function can be implemented by cascading or six input or seven input can be implemented with two four input lookup table. But we assume again worst case for the you know for the sake of argument so here we have 10 input next state logic so for one CLB can implement six input lookup table by you know two four input make a five input two five input make a six input and so on okay. Now when you have a 10 input lookup table that means that you need 16 CLBs because you can implement one CLB can implement six input lookup table. So you need two four seven four four eight and so on okay. So you will end up with the 16 CLB I definitely have kind of exaggerated it because is not the case that all the inputs all the next state decoding will require all the external input and it is even if there are really 10 input for some kind of decoding then that may not require the lookup table which is 10 input lookup table. One can cascade but assume with the worst case it happens one can kind of come out with such a scenario then what happens is that this next state logic is spread in multiple CLBs and the interconnection of that make it slow. So this clock frequency which is the TCO plus T logic plus T setup and we are talking about the logic delay of the next state logic and that can become very high and it can bring down the clock frequency of the state machine and we have analyzed the data path and we have tried to kind of be very aggressive in the kind of the timing of the data path. And suppose if you have you know designed a high performance data path but if this state machine is slow then nothing can work. So not a good solution you know the problem here is made by the next state logic which is very complex okay. So the question is how to kind of reduce the complexity of the next state logic. So if you look at it again you come back to the slide we have 5 input 5 state variables. So the question is can we reduce this is the number of state variables so and we have used a you know kind of binary encoding which necessitated a 5 flip flops for encoding 18 states. So why not encode 18 states in 18 flip flops okay. So while decoding instead of decoding a state you know when you decode a state you do not need 5 bits representing the that one state you can take one bit representing that state you know that is a basic idea. So you have there each state is a flip flop okay. So you take this kind of state transition like s a get 2 transition one from the previous state s i on condition i and s j there is a self-loop which is condition j. So the d j because this is nothing but the s j d j corresponding to this state j is nothing but condition i and s i but s i is just a single flip flop. So we say it is q i or condition j which is composed of worst case 5 input and q j because this state is represented by a single flip flop q okay q j. So you have the worst case 5 inputs specifying this input condition and 2 inputs for q i and q j. You have 7 input next side logic which require only maybe 2 CLB which is less spread and then we have less logic delay and the timing the clock frequency becomes you know manageable okay that is the idea of one hot encoding. So there is many a times people blindly like when you see FPGA you just say okay let the state machine be one hot encoded it is not required you know suppose you have a 4 state state machine with 2 input and 2 output absolutely there is no need to go for one hot encoding because this can be encoded using 2 flip flops and with 2 input the next side logic can go in one lookup table for a particular flip flop and there is absolutely no need of going for one hot encoding so but when the number of states are more, number of inputs are more then you can go for one hot encoding which eats up the flip flop but the timing becomes better which definitely is at the cost of extra flip flops but the timing is better. So this can be kind of control using some kind of attribute in VHDL code you can have a state encoding like sequential which is binary like the state 0 will have the 00 state 1 is kind of 1 and the gray is a gray code and this is a 101 and 101 which is a single flip flop for a particular state you know that is what is 101 and 101 and this can be controlled using some attributes like saying suppose you can say suppose you have to find a state type called you know enumerated state type called state type you can say attribute state encoding of state type you can say type is gray or 101, 101 things like that or you can even specify attribute enum encoding of state type, type is you can say S0 is this, S1 is this, S2 is this, S3 is this can literally specify the state encoding okay and now this is the vendor dependent this is not a part of the VHDL this is a user defined attribute. So you have to refer to the vendor tool manual whether they support it okay so we are coming to the end of the lecture so I will complete this part in the next lecture maybe another 15 minutes I will be able to complete the FPGA part then we will look at some remaining the VHDL part. So today basically we have completed the configuration we have looked at what is implemented in the current FPGA in terms of the configuration we have looked at the bit stream compression, bit stream encryption, multi boot then we have looked at this one hot encoding where the next side logic complexity can be reduced. So that the state machine works with at a faster clock so that the data it is in sync with the data path and that one hot encoding can be controlled using some attributes that is what we have discussed today and what is remaining is very minimal we will look at the complete this part and we will look at some FPGAs from other vendors very briefly one from the Altaira and one from the Hackerl and wind it up. Please review the portions I have covered so that you are in sync and I wish you all the best and thank you.


We also have in the Qur'an defined groups that God has outlined of people that he loves. So I'll read these and they're in a particular order. The first group are called the al-mahsineen and these are the doers of good. So people who are engaged in just good benevolent acts and deeds. The second are al-muktaqeen and these are those people who are mindful of God, who are really self-aware and watchful over themselves and they have the understanding that God is also ever watchful. Al-mukseteen, these are the equitable and just. So people who really push for justice and fairness. Those who purify themselves, we have a tradition of the Prophet Muhammad peace be upon him that cleanliness is part of or half of faith. So that's why you may find when you visit a mosque, for example, we will have spaces pretty large considerable spaces for the what we call the lustration or ablution that we as required of us before prayer. So Muslims will sometimes be washing our limbs face up to four or five maybe more times a day depending on how many prayers we're doing. And so cleanliness in general is a very big part of our faith. Tawabin, those who return to him. So this is repentant. People who have, who are in a state of repentant, they are, you know, they have sinned, they have perhaps lapsed and they return to God knowing that his mercy is vast and they do not let their sinfulness impede that process of returning to him no matter how many times they make mistakes. And there's quite a few different traditions of the Prophet Muhammad where he shares that even if your sins are as much as the foam of the ocean.