{"action":"created","issue":{"url":"https://api.github.com/repos/deadsy/grbl_stm32f4/issues/1","labels_url":"https://api.github.com/repos/deadsy/grbl_stm32f4/issues/1/labels{/name}","comments_url":"https://api.github.com/repos/deadsy/grbl_stm32f4/issues/1/comments","events_url":"https://api.github.com/repos/deadsy/grbl_stm32f4/issues/1/events","html_url":"https://github.com/deadsy/grbl_stm32f4/issues/1","id":97684452,"number":1,"title":"double use of USB","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":"open","locked":false,"assignee":null,"milestone":null,"comments":14,"created_at":"2015-07-28T11:42:37Z","updated_at":"2015-08-10T15:53:35Z","closed_at":null,"body":"Nice effort, this will be most useful. \r\n\r\nI quickly built and flashed this GRBL port on Fedora   ( I also did the modprobe quirks config. )\r\n\r\nHopefully it  will not be too difficult to port it for a more recent GRBL. \r\n\r\n"},"comment":{"url":"https://api.github.com/repos/deadsy/grbl_stm32f4/issues/comments/129504049","html_url":"https://github.com/deadsy/grbl_stm32f4/issues/1#issuecomment-129504049","issue_url":"https://api.github.com/repos/deadsy/grbl_stm32f4/issues/1","id":129504049,"user":{"login":"deadsy","id":3187689,"avatar_url":"https://avatars.githubusercontent.com/u/3187689?v=3","gravatar_id":"","url":"https://api.github.com/users/deadsy","html_url":"https://github.com/deadsy","followers_url":"https://api.github.com/users/deadsy/followers","following_url":"https://api.github.com/users/deadsy/following{/other_user}","gists_url":"https://api.github.com/users/deadsy/gists{/gist_id}","starred_url":"https://api.github.com/users/deadsy/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/deadsy/subscriptions","organizations_url":"https://api.github.com/users/deadsy/orgs","repos_url":"https://api.github.com/users/deadsy/repos","events_url":"https://api.github.com/users/deadsy/events{/privacy}","received_events_url":"https://api.github.com/users/deadsy/received_events","type":"User","site_admin":false},"created_at":"2015-08-10T15:53:35Z","updated_at":"2015-08-10T15:53:35Z","body":"A stepper controller (Eg the G540) generally specifies a minimum delay between any changes to the direction pin and the following step pulse. That's why the delay is needed. On the STM32 I've setup a timer whose period matches the desired step pulse period. Then I use two CCR registers to generate an interrupt at the end of the delay period, end of the step pulse and the end/start of the step period. I assume I can use the same scheme for 0.9j even though they have changed the way they are calculating the dynamics of the stepper movement. See board/timer.c"}}