{"action":"created","issue":{"url":"https://api.github.com/repos/grbl/grbl/issues/830","labels_url":"https://api.github.com/repos/grbl/grbl/issues/830/labels{/name}","comments_url":"https://api.github.com/repos/grbl/grbl/issues/830/comments","events_url":"https://api.github.com/repos/grbl/grbl/issues/830/events","html_url":"https://github.com/grbl/grbl/issues/830","id":114020861,"number":830,"title":"Homing Y axis moves twice wrong dir and says OK","user":{"login":"Shanjaq","id":451556,"avatar_url":"https://avatars.githubusercontent.com/u/451556?v=3","gravatar_id":"","url":"https://api.github.com/users/Shanjaq","html_url":"https://github.com/Shanjaq","followers_url":"https://api.github.com/users/Shanjaq/followers","following_url":"https://api.github.com/users/Shanjaq/following{/other_user}","gists_url":"https://api.github.com/users/Shanjaq/gists{/gist_id}","starred_url":"https://api.github.com/users/Shanjaq/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Shanjaq/subscriptions","organizations_url":"https://api.github.com/users/Shanjaq/orgs","repos_url":"https://api.github.com/users/Shanjaq/repos","events_url":"https://api.github.com/users/Shanjaq/events{/privacy}","received_events_url":"https://api.github.com/users/Shanjaq/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":6,"created_at":"2015-10-29T10:29:30Z","updated_at":"2015-10-29T14:47:27Z","closed_at":null,"body":"So I had homing working a little earlier, but today when I call $H the X axis will home correctly but the Y axis will make two short movements in the wrong direction and the console output will say \"OK\", as if it successfully nudged into the limit switch, but it totally didn't.\r\n\r\nWhat would cause it to make two brief movements in the wrong direction then assume all is well?\r\n\r\nI tested the limit switches by turning on hard limits $21=1 and manually nudging the platform into the limit switch, which triggered an alarm in the software (bCNC.)\r\n\r\nHere's what I did to the config.h before compiling and uploading using the \"load library\" method:\r\n\r\n#define HOMING_CYCLE_0 (1<<X_AXIS)                // REQUIRED: First move X\r\n#define HOMING_CYCLE_1 (1<<Y_AXIS)  \t\t\t  // OPTIONAL: Then move Y\r\n\r\nI also set the homing dir mask to $23=3 and inverted the limit pins 0x5=1 because they're optical and sitting at the origin."},"comment":{"url":"https://api.github.com/repos/grbl/grbl/issues/comments/152202731","html_url":"https://github.com/grbl/grbl/issues/830#issuecomment-152202731","issue_url":"https://api.github.com/repos/grbl/grbl/issues/830","id":152202731,"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":"2015-10-29T14:47:27Z","updated_at":"2015-10-29T14:47:27Z","body":"@Shanjaq : The behavior you are describing is commonly caused by electrical noise on the switch or wiring to the switch. The homing cycle is detecting the switch noise as a triggered switch and moving only the pull-off distance away from the switch. It also sounds like you have two homing locate cycles configured, which would explain the double motion. \r\n\r\nYou can verify this by removing the Y switch and using a short wire you manually bring hi and low into the Arduino pin."}}