This is a userspace application that reads the PPM audio stream produced by many RC controllers, and produces a virtual joystick using the uinput system.

This application requires two libraries, pyaudio and python-evdev. They are declared in the setup.cfg file, so will be installed if you pip install, but you can also install them using the system package manager. On Ubuntu (15.10):

sudo apt-get install python-pyaudio python-evdev

Ignore any input like the following, it is a consequence of using the Port Audio library from what I can tell.:

ALSA lib pcm.c:2267:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2267:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2267:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
ALSA lib pcm_route.c:867:(find_matching_chmap) Found no matching channel map
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started

I have only tested this with my Turnigy 9XR Pro using the JR training port, and a cheap USB audio card that got bundled with a heli sim. It has a sample rate of 48000Hz, and USB ID of 0c76:1607 JMTek, LLC. audio controller.

The only simulator that I've tried this with is FPV Freerunner. Sometimes I need to stop and start PPMAdapter to get the full range on the channels, but once it starts working it seems to keep working.

You may have to give your user access to the /dev/uinput device. This is beyond the scope of this document, but there are options using udev rules, or just chmod.

You can use the built in microphone port, or the USB one provided with some (cheap?) adapters. To see a list of candidate input devices type:

python -m ppmadapter inputs

You will get a list like this:

HDA ATI SB: VT2020 Analog (hw:0,0)
HDA ATI SB: VT2020 Digital (hw:0,1)
HDA ATI SB: VT2020 Alt Analog (hw:0,2)
HDA NVidia: HDMI 0 (hw:1,3)
HDA NVidia: HDMI 0 (hw:1,7)
HDA NVidia: HDMI 0 (hw:1,8)
HDA NVidia: HDMI 0 (hw:1,9)
USB Headphone Set: Audio (hw:2,0)
sysdefault
front
surround21
surround40
surround41
surround50
surround51
surround71
iec958
spdif
pulse
dmix
default

Then, to start the application with a specific card:

python -m ppmadapter -i hw:2 run

A partial match will be done on the name to find the right adapter. At this point if you run dmesg you should see something like the following, indicating that the device has been created.:

input: ppmadapter as /devices/virtual/input/input62

I use a Turnigy 9XR PRO running OpenTX. I've got a model setup to use PPM 1-4 channels using 22.5ms and 350us spacing, with - polarity. When you plug your controller in you should see the words Got sync written.

GPL v3