{"action":"created","issue":{"url":"https://api.github.com/repos/PX4/Firmware/issues/4983","repository_url":"https://api.github.com/repos/PX4/Firmware","labels_url":"https://api.github.com/repos/PX4/Firmware/issues/4983/labels{/name}","comments_url":"https://api.github.com/repos/PX4/Firmware/issues/4983/comments","events_url":"https://api.github.com/repos/PX4/Firmware/issues/4983/events","html_url":"https://github.com/PX4/Firmware/issues/4983","id":163748832,"number":4983,"title":"ppm issue","user":{"login":"alexFab","id":16255054,"avatar_url":"https://avatars.githubusercontent.com/u/16255054?v=3","gravatar_id":"","url":"https://api.github.com/users/alexFab","html_url":"https://github.com/alexFab","followers_url":"https://api.github.com/users/alexFab/followers","following_url":"https://api.github.com/users/alexFab/following{/other_user}","gists_url":"https://api.github.com/users/alexFab/gists{/gist_id}","starred_url":"https://api.github.com/users/alexFab/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/alexFab/subscriptions","organizations_url":"https://api.github.com/users/alexFab/orgs","repos_url":"https://api.github.com/users/alexFab/repos","events_url":"https://api.github.com/users/alexFab/events{/privacy}","received_events_url":"https://api.github.com/users/alexFab/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":8,"created_at":"2016-07-04T22:40:38Z","updated_at":"2016-07-06T19:24:58Z","closed_at":null,"body":"i try to get openLRS with PX4 to work, but no success so far. I found a [post ](http://diydrones.com/forum/topics/apm-ppm-from-openlrsng?commentId=705844%3AComment%3A1737913)where someone describes the problem.\r\n\r\n> Actually OpenLRS produces a very short 'low' pulse on the serial PPM, like 50 µs. For some systems this is not an issue, as the important data is the time between two pulses, not the pulses themselves.\r\n> But for APM (and Pixhawk), this is too short. [....] normal 300 µs low pulses and this works fine\r\n\r\nIs it possible to fix this in the current version? or is this issue known?"},"comment":{"url":"https://api.github.com/repos/PX4/Firmware/issues/comments/230879833","html_url":"https://github.com/PX4/Firmware/issues/4983#issuecomment-230879833","issue_url":"https://api.github.com/repos/PX4/Firmware/issues/4983","id":230879833,"user":{"login":"alexFab","id":16255054,"avatar_url":"https://avatars.githubusercontent.com/u/16255054?v=3","gravatar_id":"","url":"https://api.github.com/users/alexFab","html_url":"https://github.com/alexFab","followers_url":"https://api.github.com/users/alexFab/followers","following_url":"https://api.github.com/users/alexFab/following{/other_user}","gists_url":"https://api.github.com/users/alexFab/gists{/gist_id}","starred_url":"https://api.github.com/users/alexFab/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/alexFab/subscriptions","organizations_url":"https://api.github.com/users/alexFab/orgs","repos_url":"https://api.github.com/users/alexFab/repos","events_url":"https://api.github.com/users/alexFab/events{/privacy}","received_events_url":"https://api.github.com/users/alexFab/received_events","type":"User","site_admin":false},"created_at":"2016-07-06T19:24:58Z","updated_at":"2016-07-06T19:24:58Z","body":"did some measurements again. and realized there are different offsets on rc-in. the screenshots above are made while the devices are not connected, so without the offset voltage, things looks different if the devices are connected.  After rebooting, before rc-in sees a vaild ppm-signal it has this Signal:\r\n\r\n![rc-in_nothing_before](https://cloud.githubusercontent.com/assets/16255054/16631209/50d90bc2-43be-11e6-9bde-f4713b4a7f73.jpg)\r\n\r\nrc-in with connected openLRS  it looks like this:\r\n![rc-in_openlrs-befor](https://cloud.githubusercontent.com/assets/16255054/16631212/50d9f564-43be-11e6-9607-f1233f590ab7.jpg)\r\n\r\nrc-in with connected ppm simulator (detected by px4),\r\n![rc-in_simmulator](https://cloud.githubusercontent.com/assets/16255054/16631207/50d7c640-43be-11e6-9421-4523b86532e8.jpg)\r\n\r\nrc-in without any connection. the offset has changed now to 3.3V-DC\r\n![rc-in_alone_after_simconnection](https://cloud.githubusercontent.com/assets/16255054/16631210/50d9172a-43be-11e6-869c-6d5092872a10.jpg)\r\n\r\nrc-in with the 3.3V-DC offset and connected openLRS receiver.\r\n![rc-in_openlrs](https://cloud.githubusercontent.com/assets/16255054/16631208/50d8fdb2-43be-11e6-8682-1b6e38d36861.jpg)\r\n\r\nopenLRS standalone\r\n![openlrs_alone](https://cloud.githubusercontent.com/assets/16255054/16631211/50d97b5c-43be-11e6-961e-7df2a569ca3f.jpg)\r\n\r\nsimulator standalone\r\n![sim_alone](https://cloud.githubusercontent.com/assets/16255054/16631213/50ee6134-43be-11e6-93a9-1fcd4c1de90b.jpg)\r\n"}}
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