I have tried to put a PPM-SUM signal with less than 8 channels directly to an APM 2.5.
The method chosen was that described in the WIKI (http://code.google.com/p/arducopter/wiki/PPMsumRC):
- Shorten input pins 2 & 3
- Put PPM-SUM signal to input 1
The PPM-SUM signal is created by the HK-TR6A-V2 and has 6 channels.
The signal can now be measured on the PPM pad located in front of the ATMEGA 2560:
Unfortunately the radio code (used ArduCopter-2.8.1.zip) does not recognize any PPM-SUM signal.
Searching for a solution I found this comment from John Arne Birkeland who tells: "If there is less then eight channels, the decoder will update those channels and leave the unused left-over ones at the default initialization values"
So following this statement, the 6 channel PPM-SUM signal should be decoded successfully.
But looking at the decoder code I found this definition in the APM_RC library (APM_RC.h):
#define NUM_CHANNELS 8
So my questions are:
- did anybody got a working PPM-SUM configuration with other than 8 channels signal?
- has the APM_RC library to be modified when using such a signal?