Hi, the state of clean energy day. I'm your host, Mitch Ewan, all the way from the sunny shores. Well, it's sunny looking out the window now for a few minutes. I'm Panny Oybe on the flight line to the Marine Corps base. I'm really happy to have two guests here, Noel Marin from the Hawaii STEM community care organization and Dr. Craig Berger, medical doctor, MD, pediatric division chief of a local hospital on the Big Island, not to be named.  You guys are at the front lines and you've got a really novel topic today or an item to talk about and that's what you call your Hawaii 600 blue. I love that Hawaii blue reusable face mask. Noel, I'm going to start with you and we'll pop up slides as we go along to illustrate this new product that you guys have developed. Starting off, tell us about Hawaii blue. Thanks, Mitch and it's great to be here again. Thank you very much for this great service you offer to the community. If we can actually put the first slide up, I just want to essentially call attention to this new product that Hawaii STEM community care has put together. It's a reusable face mask and the catalyst for this was essentially our desire to ensure that the reusable masks, cloth masks that are being used by our residents are as safe as they can be and so we've designed this mask to enhance the quality of the masks, cloth masks that are being used out there and in the process we've uncovered additional benefits, namely the fact that we're able to utilize what would normally go into the waste stream for the hospital and that is the upcycling of polypropylene which is a fabric that's used to wrap surgical instruments and Dr. Berger can expand on this a little bit more because he's on the front lines there and importantly what we've been able to determine is a design that allows for essentially effective filtration and we were able to determine that or demonstrate that by having our masks tested in a go through a qualitative task which Dr. Berger can also expand upon. So in some we have to help our community we've designed a reusable mask utilizing polypropylene which is similar fabric that is being used for commercially made face masks and we're distributing these masks to Hawaii Island frontline workers to enhance the quality of the PPE that they're utilizing. Dr. Berger do you want to expand a bit more on the genesis of the project and also the fabric that we're focused on? Sure. Initially back in March when we started when we started having the need to wear masks we started building like regular surgical masks and everybody was looking for a material and we had actually my wife and I had started collecting this stuff because it was such this great material we knew we'd find some use for it someday so we had bags of it downstairs in our basement. So when it came up to make surgical masks we thought well this is waterproof like this stuff beads water off of it it's really unique and since they use it to sterilize equipment it's designed to repel bacteria and viruses naturally. So we started using this in regular surgical masks around summertime when we started to come to this idea that look this is going to be something we're going to be dealing with for you know maybe a year I approached Noel and the group to say like look I have this really excellent material and we can build a mask that's something more towards like a tight fitting N95 mask comparatively with this really good material. The University of Florida back in April started using this material to build N95 style masks which they actually distributed to their anesthesia staff so there's some precedent for this and so Noel's idea we all got together and sat down was look we want to build the best mask possible we want to solve all those problems that you have with the mask whether it irritates your facial hair or you know as one of the women in our group brought up like you know I wanted something that doesn't smudge my makeup I was like well that yeah problems we didn't even know we had. So that was sort of the impetus for designing this thing and we all sat down and kind of pitched it and we were lucky enough to get involved with a seamstress who just used to design bags here on the big island but she has an extensive history and like all sorts of industrial sewing and design but she's been like really excellent and that was from a so-de-kind with the name of her company. So yeah we need to get a plug in for so it's so as in sewing duh of course Hawaii for duh the pine AI NE so duh pine that's her plug. Yeah initially she was making our like surgical style mask for free and donating them out and so she was a natural person to bring in to kind of help us with this next project and she's really been like essential to getting everything exactly right.  So really to try to give them a mask that would give them as much protection as possible was what our goal was and then also to back up first line responders hospital staff or doctor's office staff who may be short on the high quality commercial grade masks as well. Well the other feature of this is it's you can cycle it as well. It's what we call that reusable. So yes yes talk about that and if you I don't know if you've put up any of the slides but let's get the numbers slide too so you can actually see what the fabric kind of looks like. Yeah this so just just a note on the fact that it's reusable. So our intention is to come up with a better reusable face mask and what I mean by that is you know the general public has access to these various cloth masks that are intended to be reused right. These are not the single use items that you would find at Home Depot for example. So the idea was that we would offer residents with a better alternative to a regular cloth mask something that would provide them with more protection and because it's reusable it's also more economical. It's intended to be used for a relatively longer period of time. So that's the intent. It's not a one time use mask or a mask that has limited life like an N95 or a surgical mask for that matter and it's meant to be a replacement for the commonly used cloth masks that you see everywhere. I'd like to yeah I'd like to maybe have us talk about the fabric itself and there is a slide three that describes the filtration capability of polypropylene and Dr. Berger you're probably in a better position to explain this. So this slide came from a study that was looking at the effectiveness of the mask or masks as you exhale or cough and so they compared several different materials and one of the things that was exciting was our material was included and now this is a surgical style mask so loose fittings flip over your ears kind of thing but made from our material and it showed that this reused material was very close or almost equivalent to a commercial grade material in either a surgical mask or an N95. So that gives you an idea that a cloth mask whether it provides some protection still allows some of the exhale or coughed out particles to pass through it and that this material actually reduces that by a substantial amount. So it makes it safer for people you're interacting with but we went ahead and tried to design a mask that would actually perhaps we were able to show somewhat in be safer for the wearer as well. Yeah as you see it's almost you know exactly almost as good as that N95-14 which is on the far you know the first item there on the left it's pretty impressive. One of the one of the exciting things that we were also able to determine is so this one would speaks to this slide speaks to the effectiveness of fabric in terms of preventing things from going through right when you're exhaling. Now there were some tests that we've conducted so which would essentially allow us to determine how effective the the the mask would be in terms of preventing stuff from going in and there are a number of tests that are being done that could be done for that and one of them is with the use of a veteran and Dr. Berger again can explain that. So I think a lot of people don't realize when we talk about N95 like when you buy them at you know Home Depot and you wear them for painting and stuff like that really for an N95 mask to work it needs to be tight fitting to your to your face it needs to not let any air in from the side. So in the hospital what we do to test for that fit is we have a we put this really looking silly plastic hood over our head and we inject a like air for eyes they're tasting kind of chemical into the hood and if the mask is doing its job when you breathe in or move around you don't taste or feel that. So we have access to that test and when we were able to show you that with our mask pulled tight tied down correctly you we could keep those bitter particles out of or I could keep those bitter particles out of my mouth. The great part about that is the bitter particle is relatively close to the same size or a little bit maybe even smaller to an aerophilized particle so a droplet that might be carrying the virus. So in the sphere and what we were able to show is that qualitatively is that if this mask is tight fitting this bitter particle won't pass through the mask and so as long as it can't sneak around the side it's probably protecting you from inhale droplets but even perhaps if somebody would you talk or cough near you those particles if the mask was tight fitting wouldn't get inside your mouth or nose that's really exciting. Yeah that's really exciting. So why don't we flip over to the next slide and talk a little bit about washing and mask wearing and all that sort of stuff. Yeah let's flip to that slide. So so this essentially is our message and it kind of summarizes our message and intention as it relates to this project. First of all we continue to encourage the proper healthy habits right mask wearing, proper hand washing and social distancing. This is going to these these activities are going to be are going to persist for a long while even given the fact that the the vaccine for the virus is here it's going to be a while before we get back before the pandemic is over. So these things are going to continue to be important. The other the other point here about caring for our community is that we're distributing these things these masks free of charge to our frontline workers. Now we are dependent on funding and we have limited supplies so we will continue to produce these as long as we have the means to and therefore will distribute while the supplies last. So how do you get the word out to the frontline workers that these are available? Yeah so we have been reaching out we have established a relationship with a number of groups based on the fact that we have been distributing PPE for several months now and you know we'll be reaching out to them. We've been advertising on social media and we've been getting some traction based on just visibility to you know the work that we've done historically and also the fact that we're doing the outreach to the general public and also certain business groups. What's been the uptake like you know this is the second show or second or third show we've had with you guys and you've been so you've been at it for many months so have you kept any data on the number of masks that you've already distributed you know the PPE you've distributed? So for the masks for the mask the we just started distributing just recently it was only the other week that we were we got to the point where we made a decision to move forward so we're making we're ramping up production and we just started advertising this week. We did get our first order from a local health care facility and we will be filling that shortly so it's it's it's nascent we haven't you know we just started distribution. As far as the general PPE distribution is concerned we've distributed you know when you take into account face shields and the mask comfort bands what we call ear savers and all the other PPE devices that we've just created we we've distributed over 3,500 or so of these items to the general public. So yeah hopefully that addresses your question Mitch we will continue to distribute as soon as long as we have the the means to and as long as the need is there. One of the things I also want to emphasize is that we we seek to empower others so the knowledge we have about the fabric the effectiveness of the fabric in terms of filtration we we want to we are socializing that with groups that make masks so that they can leverage the same technology the same you know solution to enhance the quality of the masks that are being produced. So this this is not about this there's no profit involved here we're about empowering the community we're about providing the community with the right solutions and part of that is empowering the mask makers with the same technology and design so we're we hope to be able to influence what others are producing so that will have a bigger impact. So where do you source the material I mean I know doc you got you had a supply built up you know waste not want not but you know when you run out of that eventually people are going to have to order it so is it easy to get this this material and is it expensive or what are we talking about here? The last time I think the last time I think we looked at the direct from direct order it's not that hard to get it comes in large roles I believe it was somewhere in the 40 to 60 dollar range for the roles that we were using however to be honest you know this materials it's so used in hospitals that it's really hard to you know we are backlogged in storing this stuff it's really easy to get and our production I mean we've made 500 masks and I think we basically just broke one of our collection bags so you know we'll be happy to get more and it's so easy to come by. That's awesome so better than going into the landfill right? Absolutely. Yeah, save people's lives potentially as well. So let's look at that let's call up the next slide you've got yeah so so the the question is how do you get this and if you go on to the next slide you can visit our website highstemcare.org forward slash shop and you will be able to you'll be you'll be taken to this this shop this this store online store essentially and on here just below the fold and you go you can go to the next slide you'll see access to the product page and this is where you're able to place an order and once the order is placed we will we will process them on a first come first serve basis. I'm sorry go ahead oh yes yes I have a sample right here. Wow it's actually not a bad looking mask. Thank you yeah so so the key is visiting the website Hawaii STEM or I'm sorry highstemcare.org and there you'll find the link to PPE and the shop and again this is this is available to Hawaii Island frontline workers we if there are requests from other groups we will you know we will address them on a first come first serve basis with priority of course to our frontline workers and the the next slide is well it's it's essentially a summary of how we're made how this is coming together I want to highlight and the efforts of the Hawaii STEM community care team that's you know worked on this diligently for a few months now. The helo medicals who are they what does STEM mean and remind everybody who the STEM community care team is and what they're made up of yeah so STEM is science technology engineering and math so this is a number it's a hui essentially that was formed early this year in response to the pandemic and the need for solutions to address the PPE shortage. So we have a number of organizations and individuals associated with STEM so STEM education STEM industry you've got Canada France Hawaii telescope you've got Pisces you've got Hawaii Science and Tech Museum Next Tech Hawaii so a number of organizations and their volunteers who have essentially formed this coalition and we have a number of projects that have gone through that we've gone through and also a number of projects in flight and it's all through the generosity of our volunteers. And you have a lot of students involved in this too right? Yes yes we have a little bit about that how the students are becoming involved. Yeah so one of the things that one of the motivations for this particular group is to also encourage interest in STEM and and one way to do that is to actually involve students directly in the process and there have been projects where they actually have done that and what I mean by that is actually be involved in helping with the design of a certain product. The other thing that we try to do is to share the experience that we've gone through to come up with these things with students and in that that process of understanding how a group of individuals would arrive at assessing a problem arriving at potential solutions after identifying root cause testing the solutions and then coming up with the solutions is that that whole process is something that we also aim to impart to students that are affiliated with our STEM groups. So Dr. Berger can you tell us a little bit about the Hilo Medical Center Foundation? So the HMC Foundation is a group that's put together to help provide more resources to the hospital you know they have done things they do have I know they do a yearly like wine and cheese event to help they provide on a very visible level they come around daily with books and items that they give away free to patients who are in the hospital to help them entertain themselves and stuff like that. They work with school groups they do educational outreach they kind of seem to handle a lot of the donation money for the hospital and for us they provide sort of like a filter for the material for us which is nice too they're actually receiving the material from the hospital and it's getting gifted from the hospital to them and then they gift it to us and that kind of gets rid of any awkward you know ownership issues that come with the material. That's been really nice as well they worked with that and they've been working with us without any sort of compensation or requesting anything with us they just want the specific feed and help us take care of our community. So does Kona have a similar one? I see it's Hilo. What about Kona? Do they have a similar organization? I do not know I mean the Kona hospital is like I would wouldn't be surprised but the Kona hospital is like a different entity than us all together. So talk to us a little bit about how you're raising money for this like the mechanics of raising money how do we do that because this it's not free I mean nothing is free you're giving them out free but you require you know you require the generosity of donors out there so how does that work? So the initial funding for the first batch of masks were courtesy of NEXTEC as well as the Hawaii Science and Technology Museum and these organizations receive funding from other organizations like the Hawaii Community Foundation is an example. So the initial batch of masks were funded through those two organizations and we were fortunate enough to have a local donor step up with the opportunity to match up to $15,000 of their donation so we at the moment are also starting to ramp up a fundraising opportunity which is to reach out to potential donors to donate to the project and there will be a match up to again $15,000 from our generous local donor and for folks who are interested in donating if you go to the next slide there is on our website again it's highstemcare.org on the upper right hand corner of the screen there's a donate button and there's the opportunity for us to for anyone to make a tax deductible contribution to the organization. What about if you received any county money or state money to support your areas? Not for this particular project although we are reaching out and are hopeful that we might be able to obtain some funds from the governor. Okay so if you go to your website I mean what about you talked about other people being able to make these or what about getting a set of plans and instructions on how to make these masks? I remember Richard Haw came out with a right at the start of the pandemic with a very good set of plans and patterns for actually making them right down to how you stitch it. Have you developed like a user package there of how you can make one of these? You want to speak to that Craig? Yeah so initially I do have a website with like a surgical style mask pattern for the blue for the blue wrap it uses a different thinner material similar but it's a little more pliable and we have so we have a website for that you know right now we're using this as a way our seamstress you know from SodaKind this is a way to help her put her company back in business and well I shouldn't say her company but to reach out to all of her seamstresses that she had to put out of work during the pandemic to sort of give them some sort of revenue. I think on top of that there is some work with North Hawaii and that they're starting to collect the material and that I think from there we can put together a pattern so I think we're now in the still in this kind of initial stage that we don't have this design yet in a ready-to-go package for easy duplication but I definitely think it's something in the works down the road. I'd like to expand on that yeah so so any interested parties can get and can contact us also through the website there's a contact us link at the top and we will collaborate with them to help them understand access to the fabric and then also we ultimately are going to be sharing you know designs plans but yeah the key is to get in touch with us and we will respond and provide them with whatever information is necessary. So again on the on the website there's a contact us link in the header they just have to visit highstemcare.org okay I'm not sure if we talked about it but what talk a little bit more about regenerating one so you when we started before we started the show the rough you don't put it in the washing machine and wash it you know with your laundry correct correct the material this this material and what they use in regular N95 masks it's not just a mesh material it also has like this case this electrics electric charge that helps prevent the viruses from you know passing through the mask and so that is needs to be protected so you can't throw it in a wash machine with soap and water because the detergent will interfere with that process so we've come up with a couple of different ways one of the one way is that we do a dry heat version where you can put in the oven I believe it's 160 degrees for about 30 minutes and that will clean or remove any of the contaminants from the mask you can also boil it in water for a couple of minutes I believe it's two or three minutes and that will also sanitize the mask and then you have to like lay it out to dry but there's also been stuff published to do you can clean like an N95 using dry heat like in a rice cooker or instant pot um I believe that's a you know I don't know I don't have any data for a hair dryer and that's kind of you know anything with I imagine dry heat would work I don't know how long or how much and because with a hand hair dryer I would imagine you have a lot of variation in you know as you waving it around it might be hard to be very consistent but I was going to I mean the ovenware is definitely an easy way of doing it okay so we're coming up to the end of our time believe it or not um let's look at the last slide and uh Noel let's let's hit the uh the contact part to make sure that everybody knows how to get involved in this program um yeah so I just let me just emphasize highstemcare.org is the website and from there you can access the various information about the PPEs including this particular product if you want to go directly to this product page it's highstemcare.org forward slash hi 600 and um there is a contact us link on the website but if there's a desire to get in touch with someone directly my email address is and Noel G. Morin at gmail.com so that's the end of our show believe it or not this uh so actually this is the last show uh for me for 2020 I'll be back I hope in 2021 maybe if I have one year mass I can make sure that I come back I well we'll get we'll say we'll get one year away yeah well I'll I'll pay for that so anyway I've been very happy to have Noel and Craig here thank you for your service Craig you're on the front lines man like we said before the show started I admire what you're doing for all of us out there and protecting us you're going in harm's way so thanks so much um and that's uh think tec hawai hawai the state of clean energy winding up aloha aloha


Thankfully, it's November and Appalachian Wireless is offering the Samsung GS8 or the GS8 Plus for $100 off the regular price with two-year agreement. Better service, bigger savings. That's today's Appalachian Wireless, an East Kentucky network company. The building is dark right now, but Mayor Les Stapleton and the city of Prestonsburg today took a step they hope will soon not only bring new life to a vacant structure, but new life to the southern end of Prestonsburg. You know, this is an exciting step for Prestonsburg. You know, the fact that we're able to obtain a property that we can start with a community center and, you know, it may be three years down the road before we ever get it in place. But this is a step.  City leaders today signed paperwork to purchase the old Music Carter Hughes showroom, garage, and lot on Southlake Drive. Their plans call for converting the existing building and constructing another to serve as a new Prestonsburg community center. Some features of the building are already set in stone, including a field house with artificial turf, a twin-screen movie theater, party rooms, and a playground area. But other plans are more flexible and Stapleton is welcoming community input. We've actually talked about putting a tent up up there and having an open public meeting.  You tell us what we want. You know, it's the communities. It's not something less stable wants to do. It's not something city council wants to do. It's the community. So if they want to see something in there, they need to come get involved. Supporters of the building, and there are many, say the center is something Prestonsburg has needed for a long time. Growing up here in Eastern Kentucky and Prestonsburg, we didn't have anything like this. I played outside a lot in the yard, but we didn't have anywhere we could go meet with friends in a safe environment and just play, you know. And I think it's going to be great for all age groups, like you said, from 8 to 85, you know, we'll have something for everyone there. The project differs significantly from a similar effort four years ago, most notably in cost. The property was acquired for less than half of what a previous site would have cost, and the renovations and constructions are expected to be a third of the earlier plan. And now, with Deed in hand, Stapleton says he is going to go after money to make the center a reality as soon as possible. It's one of those things where if I've got a project ready, or a shovel ready project, which means, look, this is what I've got. I've got it here. We're ready to go with it. I need money to get started. It's easier to get money. So basically what I'm going to be doing is I'm going to run up that deed in Frankfurt saying, hey, look, let's work. Stapleton says there is currently no timetable set for when the facility might open. That, he says, depends on funding. Reporting in Prestonsburg, I'm Ralph Davis for EKB News.


Welcome to the series, Photographic Chemistry, presented by the Foundation of the American Institute for Conservation of Historic and Artistic Works. This program was made possible by grants from the National Endowment for the Humanities and the Andrew W. Mellon Foundation. Each program in this series is presented as a short video. Depending on your video viewer, you should be able to pause, return to a previous section, or skip ahead to a later section by using a scroll bar or on-screen icons. You will find an outline of the course and short quizzes to test your understanding on the course webpage. There are other defects that matter in the chemical and light sensitivity to silver halide grains and emulsions. These tend to be more macroscopic in nature than the more point defects that we've discussed in the previous slides. But they still matter in changing the reactivity of these silver halide crystals to chemical development, sensitization, and exposure. So the classes of the much more macroscopic defect tend to fall into a class called dislocations. These are shifts, sort of like twining that we discussed earlier, where we form clefts and ridges and edges. Anytime these defects form, these are going to be sites of different surface chemistry. They're going to have different combinations of ions present. Then you would find in the bulk of the crystal. In chemistry, we call these areas which have an increased chemical reactivity. They're much more chemically active. And so these clefts and dislocations form more trap sites. And here's another time that I've used this word trap site. In being more chemically reactive in terms of photographic chemistry and silver halide chemistry in particular, we're talking about the trapping of the mobility of ions, particularly of silver. So when we talk about latent image theory, I'm going to be referring to these trap sites. They can be correlated directly to all the concepts we've discussed up to this point. These are dislocations and defects within the crystal. So when I say trap site, I'm talking about a defect site. Either a point defect or a dislocation of some kind. They can be electron traps where they'll trap silver. This could be an example of an area which might have a more negative charge, which is attracting the silver. Or they can be an area where silver sort of congregated. And this would represent what's called a whole trap. And they form a trap which holds the reactive halide ion. Now when I use this term in latent image theory, this is where gelatin gets involved in the process. But we have to wait until we can discuss that in a lot more detail. Each crystal, as I mentioned before, has a plurality of defects and dislocations. And these are going to be sites where a lot of the photochemical reactivity is going to occur. And there's about a dozen or so of these trap sites in every crystal. You have completed this unit. Depending on your video viewer, you should be able to scroll back to any point in the video as desired. The short quiz found in the course materials on the website may help you confirm your understanding of the concepts introduced here. Many thanks to the instructor, production editor, coordinator and the collaborative workshops in Photograph Conservation Committee for their work to make this program possible.


Hello and welcome to this presentation of the embedded flash memory which is included in all products of the STM32U5 microcontroller series. This table summarizes the features of the flash memory existing in STM32U5. Depending on the product, the flash size can be up to 4 megabytes. It also embeds a one-time programming area of 512 bytes. The flash read data bus width is 128 bit. STM32U5 always supports a dual bank architecture. The swap bank option in the user option bytes is used to swap bank 1 and bank 2 addresses. Note that read while write capability, or RWW, is therefore always supported by the STM32U5. The page size which provides the minimum erase granularity is 8 kilobytes. STM32U5 has an increased endurance of up to 100 kilocycles on 256 kilobytes per bank. It also supports a read-prefetch unit that increases the efficiency of Cortex M33C AHB bus. Finally, STM32U5 implements a flexible life cycle scheme with readout protection, RDP, including support for product decommissioning even from level 2 using passwords. Each program erase operation can degrade the flash memory cell. After an accumulation of program erase cycles, memory cells can become non-functional causing memory errors. Injurance is the maximum number of erase programming sequences that the flash memory can support without affecting its reliability. 256 kilobytes, 32 pages, per bank feature an increased endurance of 100 kilocycles that can be used for data storage that usually needs more intensive cycling capability than code storage. Any flash page can be chosen to be cycled more than 10,000 times up to 100,000 times. It is the application's responsibility to limit the size of the flash area cycled more than 10,000 times to 256 kilobytes per bank. Data in flash memory are 137 bits wide, 9 bits are added per each quad-word of 128 bits. The ECC mechanism supports one error detection and correction, two error detection when one error is detected and corrected. The ECC flag, ECC correction, is set in the flash ECC register. An interrupt can be generated when two errors are detected. The ECCD flag, ECC detection, is set in the flash ECC register. In this case, an NMI is generated. The address and bank number at which the error has been detected are captured in status registers for further investigation. To correctly read data from the flash memory, the number of white states, latency, must be correctly programmed according to the frequency of the CPU clock, HCLK, and the internal voltage range of the device, V-core. The table below shows the correspondence between white states and CPU clock frequency. LPM, the flash memory supports a low-power read mode when setting the LPM bit in the flash access control register, flash ACR. The Cortex M33 fetches instructions and literal pool constants over the CBUS and through the instruction cache if it is enabled. The pre-fetch block increases the efficiency of CBUS accesses when the instruction cache is enabled by reducing the cache refill latency. Pre-fetch is efficient in the case of sequential code. Pre-fetch in the flash memory allows the next sequential instruction line to be read from the flash memory while the current instruction line is being filled in instruction cache and executed by the CPU. Pre-fetch is enabled by setting the PRFTN bit in the flash access control register, flash ACR. PRFTN must be set only if at least one weight state is needed to access the flash memory. Note that pre-fetch tends to increase the code execution performance at the cost of extra flash memory accesses. It may impact power consumption when activated, but power efficiency is better thanks to the increased performance. Here are some performance metrics expressed in CoreMark per megahertz. Performance when iCache is off and pre-fetch is off is 2.2. Performance when iCache is off and pre-fetch is on is 2.7. This illustrates the performance increase thanks to pre-fetch in the case of a cache miss. As CoreMark code is entirely in iCache, no cache miss after the first iteration, pre-fetch has no impact on the CoreMark score when iCache is enabled. The flash memory consumption can be reduced when the code is not executed from flash. After reset, both banks are in normal mode. In order to reduce power consumption, each bank can be independently put in power down mode by setting the PDR EQX bit. Any access to a bank in power down mode automatically wakes up the bank. It takes at least 5 microseconds to wake up the bank. A power down bank saves 45 microamperes. Power down flash in sleep mode saves 90 microamperes. Activating the low power read mode by setting the LPM bit in the flash access control register flash ACR saves 50 microamperes at the expense of an increased latency. Read, program and erase operations are supported in all voltage ranges. When trust zone is enabled, the non-secure software is only permitted to access the non-secure part of the flash. Erase can be performed with a page granularity for one bank or both banks. In the latter case, this is called a mass erase. The flash controller implements two programming modes. Single quadward, called normal mode. Eight quadwards representing 128 bytes, called burst mode. In both cases, the ECC code is calculated and added to the data so that 137 bits are actually programmed. Programming 1 megabyte at 160 megahertz takes 7.7 seconds in normal mode, 3.1 seconds in burst mode. The contents of the flash memory currently being accessed are not guaranteed if a reset occurs during a flash memory program or erase operation. The status of the flash memory can be recovered from the flash operation status register when a system reset occurs during a flash memory program or erase operation. It is the software's responsibility to check the flash memory status and to take corrective actions. This slide provides some metrics regarding flash program and erase operations. The time to program a quadward plus ECC code is 48 microseconds when burst mode is used. The time to fully erase the two banks is 390 milliseconds. The time to erase one page assuming 10 kilo endurance cycles is 1.5 millisecond. An internal algorithm manages the erase sequence and the erase time increases when the number of endurance cycles increases. An additional 0.2 millisecond is typically required when erasing a page with 100 kilo cycles. The internal 16 MHz oscillator, HSI 16, is automatically enabled when an erase or programming sequence starts and automatically disabled when this sequence completes except if the HSI 16 was previously enabled. When trust zone security is active, a part of the flash memory can be protected against non-secure read and write accesses. Deactivation of trust zone is only possible when the readout protection or RDP is changed from level 1 to level 0. Up to two different non-volatile secure areas can be defined by option bytes and can be read or written only by a secure access. When area per bank with a page granularity, each of them supports a secure hide protection area starting at the same start page offset and ending at a programmable end page offset. The contents of the secure hide protection area is marked as non-accessible after the corresponding HDP-ACC-DIS bit is set to 1. This is used to prevent subsequent access to a part of the flash and is used to isolate the secure boot code and data from both secure and non-secure application codes. Any flash page can be set as secure non-secure thanks to dedicated secure registers in the flash interface. Flash SECBB1RX with X equals 1 to 8 and flash SECBB2RX with X equals 1 to 8. At reset, these registers are cleared, non-secure. A page which already belongs to a secure watermark area will be secure whatever its block-based bit configuration. In each security domain, the privileged level of each flash page is programmable, either unprivileged or privileged, by means of flash PRIBB1RX with X equals 1 to 8 and flash PRIBB2RX with X equals 1 to 8 registers. Four quadrants of isolated worlds are thus obtained. Secure privilege, secure non-privilege, non-secure privilege, non-secure non-privilege. Regarding the RDP state machine, STM32U5 implements a new feature, OEM1, OEM2 lock activation. Two 64-bit keys, OEM1 key and OEM2 key can be defined in order to lock the RDP regression from level 1 or to allow the regression from level 2. Each 64-bit key is coded on two registers. OEM1 key and OEM2 key cannot be read through these registers. In order to regress from RDP level 1 to RDP level 0, the debugger has to provide the correct OEM1 key value. In order to regress from RDP level 1 to RDP level 0.5, the debugger has to provide the correct OEM2 key value. In order to regress from RDP level 2 to RDP level 1, the debugger has to provide the correct OEM2 key value. When these keys are not provisioned, the STM32U5 only implements the legacy transitions. When the RDP is set to level 2 and the OEM2 key is not provisioned, JTAG and SWD are definitely disabled. If the OEM2 key is provisioned, the JTAG and SWD remain enabled under reset only to obtain device identification and provide the OEM2 key to request RDP regression. Refer to the security training for more information about the device lifecycle. For write protection areas are supported, two per bank. Program and erase operations are prohibited in write protection areas. Consequently, a software mass erase cannot be performed if one area is write protected. Each area is defined by a start page offset and an end page offset related to the physical flash bank base address. Each write protection area can be independently locked. In this case, it is not possible to modify the area settings and the unlock can be done only thanks to RDP regression to level 0. The write protection attribute is orthogonal to the secure and HDP settings. Thank you for following this online training.