{"action":"created","issue":{"url":"https://api.github.com/repos/diydrones/ardupilot/issues/1827","labels_url":"https://api.github.com/repos/diydrones/ardupilot/issues/1827/labels{/name}","comments_url":"https://api.github.com/repos/diydrones/ardupilot/issues/1827/comments","events_url":"https://api.github.com/repos/diydrones/ardupilot/issues/1827/events","html_url":"https://github.com/diydrones/ardupilot/issues/1827","id":55827110,"number":1827,"title":"RXRSSI bottom end calibration","user":{"login":"JSGordon","id":8051473,"avatar_url":"https://avatars.githubusercontent.com/u/8051473?v=3","gravatar_id":"","url":"https://api.github.com/users/JSGordon","html_url":"https://github.com/JSGordon","followers_url":"https://api.github.com/users/JSGordon/followers","following_url":"https://api.github.com/users/JSGordon/following{/other_user}","gists_url":"https://api.github.com/users/JSGordon/gists{/gist_id}","starred_url":"https://api.github.com/users/JSGordon/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/JSGordon/subscriptions","organizations_url":"https://api.github.com/users/JSGordon/orgs","repos_url":"https://api.github.com/users/JSGordon/repos","events_url":"https://api.github.com/users/JSGordon/events{/privacy}","received_events_url":"https://api.github.com/users/JSGordon/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":5,"created_at":"2015-01-28T22:41:27Z","updated_at":"2015-03-06T14:42:36Z","closed_at":null,"body":"There is a feature now in APM which allows for a analog input from receivers such as FRsky.  Already in code for 3.2 there is the ability to set voltage input range to calibrate the 100% RSSI point.\r\nHowever there is no such feature to set the low point.\r\n\r\nThe FRsky RSSI output is a PWM output that typically is integrated into a DC analog input with a resistance capacitance filter.  Since the PWM pulse train typically varies from 1000 to 2000 milliseconds the analog DC never goes to zero.  Other implementations typically allow for both top end voltage and bottom end voltages to be set based on observed values.\r\n\r\nIt would be nice if this capability existed in APM as well.  From my experience recently the usable range is compressed into what APM shows as ~60 to 100% with 60 being the point where control may be lost."},"comment":{"url":"https://api.github.com/repos/diydrones/ardupilot/issues/comments/77568961","html_url":"https://github.com/diydrones/ardupilot/issues/1827#issuecomment-77568961","issue_url":"https://api.github.com/repos/diydrones/ardupilot/issues/1827","id":77568961,"user":{"login":"JSGordon","id":8051473,"avatar_url":"https://avatars.githubusercontent.com/u/8051473?v=3","gravatar_id":"","url":"https://api.github.com/users/JSGordon","html_url":"https://github.com/JSGordon","followers_url":"https://api.github.com/users/JSGordon/followers","following_url":"https://api.github.com/users/JSGordon/following{/other_user}","gists_url":"https://api.github.com/users/JSGordon/gists{/gist_id}","starred_url":"https://api.github.com/users/JSGordon/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/JSGordon/subscriptions","organizations_url":"https://api.github.com/users/JSGordon/orgs","repos_url":"https://api.github.com/users/JSGordon/repos","events_url":"https://api.github.com/users/JSGordon/events{/privacy}","received_events_url":"https://api.github.com/users/JSGordon/received_events","type":"User","site_admin":false},"created_at":"2015-03-06T14:42:36Z","updated_at":"2015-03-06T14:42:36Z","body":"Interesting.  This is what I had expected the RSSI output to look like.  However it is not on the same time period nor does it have the same low pulse width and as mentioned the waveform does not look even close.  I am not seeing at any time even with radio off a 1% duty cycle hence the need for low end calibration\r\nPWM channels look fine.  Of course the is for the D4R-II for my measurements.\r\n\r\nHave tried on 2 D4R-II units with same waveform results.  Nonetheless it is a usable output."}}