{"action":"created","issue":{"url":"https://api.github.com/repos/grbl/grbl/issues/748","labels_url":"https://api.github.com/repos/grbl/grbl/issues/748/labels{/name}","comments_url":"https://api.github.com/repos/grbl/grbl/issues/748/comments","events_url":"https://api.github.com/repos/grbl/grbl/issues/748/events","html_url":"https://github.com/grbl/grbl/issues/748","id":90767469,"number":748,"title":"Adding SPI ","user":{"login":"J-Dunn","id":9969512,"avatar_url":"https://avatars.githubusercontent.com/u/9969512?v=3","gravatar_id":"","url":"https://api.github.com/users/J-Dunn","html_url":"https://github.com/J-Dunn","followers_url":"https://api.github.com/users/J-Dunn/followers","following_url":"https://api.github.com/users/J-Dunn/following{/other_user}","gists_url":"https://api.github.com/users/J-Dunn/gists{/gist_id}","starred_url":"https://api.github.com/users/J-Dunn/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/J-Dunn/subscriptions","organizations_url":"https://api.github.com/users/J-Dunn/orgs","repos_url":"https://api.github.com/users/J-Dunn/repos","events_url":"https://api.github.com/users/J-Dunn/events{/privacy}","received_events_url":"https://api.github.com/users/J-Dunn/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":15,"created_at":"2015-06-24T19:53:19Z","updated_at":"2015-06-27T21:26:39Z","closed_at":"2015-06-24T20:49:08Z","body":"I'm trying to add some hardware using driver chips programmed via SPI.  Mostly initialisation but also error status.  Usual step and dir lines. \r\n\r\nArduino SPI lib is pretty trivial since most of it is done by the hardware. It's mostly poke a byte into a register and wait for a status flag, then read the return byte. \r\n\r\nI'll need to shift the default pins around a bit to free up MOSI and friends, so I won't have spindle control ( not needed ) and limit pins will have to go onto port A. \r\n\r\nNow I know GRBL has been squeezed to a minimum to get it to fit into a UNO. How much room do I have left to play with before it starts giving problems? What are the limits I need to pay particular attention to? \r\n\r\nThanks  JD. \r\n\r\n"},"comment":{"url":"https://api.github.com/repos/grbl/grbl/issues/comments/116145418","html_url":"https://github.com/grbl/grbl/issues/748#issuecomment-116145418","issue_url":"https://api.github.com/repos/grbl/grbl/issues/748","id":116145418,"user":{"login":"chamnit","id":948029,"avatar_url":"https://avatars.githubusercontent.com/u/948029?v=3","gravatar_id":"","url":"https://api.github.com/users/chamnit","html_url":"https://github.com/chamnit","followers_url":"https://api.github.com/users/chamnit/followers","following_url":"https://api.github.com/users/chamnit/following{/other_user}","gists_url":"https://api.github.com/users/chamnit/gists{/gist_id}","starred_url":"https://api.github.com/users/chamnit/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/chamnit/subscriptions","organizations_url":"https://api.github.com/users/chamnit/orgs","repos_url":"https://api.github.com/users/chamnit/repos","events_url":"https://api.github.com/users/chamnit/events{/privacy}","received_events_url":"https://api.github.com/users/chamnit/received_events","type":"User","site_admin":false},"created_at":"2015-06-27T21:26:39Z","updated_at":"2015-06-27T21:26:39Z","body":"You sure about that? Check stepper.c's initialization routines. I think you'll find that it's not true. "}}