{"action":"created","issue":{"url":"https://api.github.com/repos/hzeller/rpi-rgb-led-matrix/issues/65","labels_url":"https://api.github.com/repos/hzeller/rpi-rgb-led-matrix/issues/65/labels{/name}","comments_url":"https://api.github.com/repos/hzeller/rpi-rgb-led-matrix/issues/65/comments","events_url":"https://api.github.com/repos/hzeller/rpi-rgb-led-matrix/issues/65/events","html_url":"https://github.com/hzeller/rpi-rgb-led-matrix/issues/65","id":105238153,"number":65,"title":"Use of left GPIO pins","user":{"login":"samuqu","id":11449584,"avatar_url":"https://avatars.githubusercontent.com/u/11449584?v=3","gravatar_id":"","url":"https://api.github.com/users/samuqu","html_url":"https://github.com/samuqu","followers_url":"https://api.github.com/users/samuqu/followers","following_url":"https://api.github.com/users/samuqu/following{/other_user}","gists_url":"https://api.github.com/users/samuqu/gists{/gist_id}","starred_url":"https://api.github.com/users/samuqu/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/samuqu/subscriptions","organizations_url":"https://api.github.com/users/samuqu/orgs","repos_url":"https://api.github.com/users/samuqu/repos","events_url":"https://api.github.com/users/samuqu/events{/privacy}","received_events_url":"https://api.github.com/users/samuqu/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":1,"created_at":"2015-09-07T15:42:09Z","updated_at":"2015-09-13T21:30:08Z","closed_at":null,"body":"Hi, I want to show my appreciation for this wonderful piece of code, I've been able to make it work with a custom led panel.\r\nHowever, I've encountered a problem when I wanted to use the leftover pins on the GPIO to input some signals from some infrared sensors, as I want to make an interactive application.\r\nI'm very new to C++ so I opted for Python, and used the RPi.GPIO.add_event_detect() to wait for the trigger, however, the signal gets some noise whenever the display is lit.\r\nI assumed RGBMatrix was still trying to write to those pins, and I tried uncommenting the `#DEFINES+=-DONLY_SINGLE_CHAIN` in lib/Makefile and even commenting the pins I'm using in `kValidBits` in lib/gpio.cc but to no avail, I still get false triggers on my sensors.\r\nI hope someone can point me to the right direction\r\nCheers,\r\nSamu"},"comment":{"url":"https://api.github.com/repos/hzeller/rpi-rgb-led-matrix/issues/comments/139919128","html_url":"https://github.com/hzeller/rpi-rgb-led-matrix/issues/65#issuecomment-139919128","issue_url":"https://api.github.com/repos/hzeller/rpi-rgb-led-matrix/issues/65","id":139919128,"user":{"login":"hzeller","id":140937,"avatar_url":"https://avatars.githubusercontent.com/u/140937?v=3","gravatar_id":"","url":"https://api.github.com/users/hzeller","html_url":"https://github.com/hzeller","followers_url":"https://api.github.com/users/hzeller/followers","following_url":"https://api.github.com/users/hzeller/following{/other_user}","gists_url":"https://api.github.com/users/hzeller/gists{/gist_id}","starred_url":"https://api.github.com/users/hzeller/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/hzeller/subscriptions","organizations_url":"https://api.github.com/users/hzeller/orgs","repos_url":"https://api.github.com/users/hzeller/repos","events_url":"https://api.github.com/users/hzeller/events{/privacy}","received_events_url":"https://api.github.com/users/hzeller/received_events","type":"User","site_admin":false},"created_at":"2015-09-13T21:30:08Z","updated_at":"2015-09-13T21:30:08Z","body":"Which GPIOs do you want to use ? Usually, if you don't use all three parallel chains, the ones that are not used by the panels should be free and are untouched by the rgb-led-matrix library (-P1 for instance only uses pins for the first chain). At least, they are not set for writing in the library.\r\n\r\nHowever, I have not explicitly tested myself if the input on other GPIO pins works or is disrupted by other things.\r\n\r\nOne important thing to make sure is that you dont' stray too much electrical trouble into the inputs. Make sure to have a separate solid ground connection from the ground of the panel to the ground of the RPi so that the load on the panel does not shift levels. A low ESR capacitor at the power input of the panel can help as well getting less noise injected.\r\n\r\nKeep signal cables from the Pi to the panel as short as possible to not strain the GPIO output drivers to much; maybe add a HCT245 to separate these (similar to what is done in https://github.com/hzeller/rpi-rgb-led-matrix/tree/master/adapter/active-3 )."}}