{"action":"created","issue":{"url":"https://api.github.com/repos/grbl/grbl/issues/931","repository_url":"https://api.github.com/repos/grbl/grbl","labels_url":"https://api.github.com/repos/grbl/grbl/issues/931/labels{/name}","comments_url":"https://api.github.com/repos/grbl/grbl/issues/931/comments","events_url":"https://api.github.com/repos/grbl/grbl/issues/931/events","html_url":"https://github.com/grbl/grbl/issues/931","id":140032015,"number":931,"title":"Level Translator for 3.3v to 5v","user":{"login":"Moffy","id":2441764,"avatar_url":"https://avatars.githubusercontent.com/u/2441764?v=3","gravatar_id":"","url":"https://api.github.com/users/Moffy","html_url":"https://github.com/Moffy","followers_url":"https://api.github.com/users/Moffy/followers","following_url":"https://api.github.com/users/Moffy/following{/other_user}","gists_url":"https://api.github.com/users/Moffy/gists{/gist_id}","starred_url":"https://api.github.com/users/Moffy/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Moffy/subscriptions","organizations_url":"https://api.github.com/users/Moffy/orgs","repos_url":"https://api.github.com/users/Moffy/repos","events_url":"https://api.github.com/users/Moffy/events{/privacy}","received_events_url":"https://api.github.com/users/Moffy/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":11,"created_at":"2016-03-10T22:51:19Z","updated_at":"2016-03-11T22:49:04Z","closed_at":null,"body":"If GRBL moves to a newer ARM style board, some older systems will need the output levels boosted from 3.3v to 5v. I am including a possible solution.\r\n[GRBL_3v3_to_5v.pdf](https://github.com/grbl/grbl/files/168127/GRBL_3v3_to_5v.pdf)\r\nThe circuit would use 3, 14pin IC's which are available in PDIP or non surface mount packages making it easy for the hobbyist to fabricate. The buffer IC's would do the level translating as well as providing drive for the signals. An extra signal is included 'STEP_CLK' which provides a 1us delay for the STEP_X_OUT etc signals. This would give a suitable setup time for the DIR_X_OUT etc signals to be applied before the step pulse is generated.\r\nThe idea is that the STEPPER timer interrupt would output all the step, dir and STEP_CLK at the same time and the hardware delay on the step pulses would provide a suitable setup time. The STEPPER timer interrupt would then, say 10us later reset the step and STEP_CLK pulses. This would slightly simplify the STEPPER timer interrupt. It would also mean that as the processors get faster less cycles would be wasted for the step setup time delay.\r\nThe circuit would also have headers so that the user could choose between the normal and inverted output, meaning that the invert mask could be removed also.\r\n"},"comment":{"url":"https://api.github.com/repos/grbl/grbl/issues/comments/195591339","html_url":"https://github.com/grbl/grbl/issues/931#issuecomment-195591339","issue_url":"https://api.github.com/repos/grbl/grbl/issues/931","id":195591339,"user":{"login":"Protoneer","id":3835171,"avatar_url":"https://avatars.githubusercontent.com/u/3835171?v=3","gravatar_id":"","url":"https://api.github.com/users/Protoneer","html_url":"https://github.com/Protoneer","followers_url":"https://api.github.com/users/Protoneer/followers","following_url":"https://api.github.com/users/Protoneer/following{/other_user}","gists_url":"https://api.github.com/users/Protoneer/gists{/gist_id}","starred_url":"https://api.github.com/users/Protoneer/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Protoneer/subscriptions","organizations_url":"https://api.github.com/users/Protoneer/orgs","repos_url":"https://api.github.com/users/Protoneer/repos","events_url":"https://api.github.com/users/Protoneer/events{/privacy}","received_events_url":"https://api.github.com/users/Protoneer/received_events","type":"User","site_admin":false},"created_at":"2016-03-11T22:49:04Z","updated_at":"2016-03-11T22:49:04Z","body":"What speed signals can stepper drivers handle?\n\nI had a look at A4988 drivers the other day and I think they could go up to\n300Khz max... (anyone able to confirm that number?)\nOn 12/03/2016 11:38 am, \"109JB\" <notifications@github.com> wrote:\n\n> \"If you use MOSFET level translators you are going to need to buffer them\n> with say a 74HCT14,\"\n>\n> Why? I have had contact with people using TinyG2 on Arduino Due and they\n> reported that the cheapo logic level converters alone worked fine for\n> interfacing to external stepper drivers.\n>\n> Wouldn't another option would be to use high speed optocouplers to perform\n> the level shift.?\n>\n> —\n> Reply to this email directly or view it on GitHub\n> <https://github.com/grbl/grbl/issues/931#issuecomment-195586199>.\n>\n"}}