Failsafe mode does not work

[Arne-W]

The failsafe mode does not work cause of the rcSerialCount decreases to 0 if the controller disconnects. If its 0 the code sets the input values to 1500 (see #16 ).

To fix this we have to do some changes:

The failsafe mode must be enabled :-) https://github.com/koenkooi/multiwii-firmware/blob/pruts/config.h#L577

The normal RC should be disabled by inserting #if !defined(RC_TINY) after line https://github.com/koenkooi/multiwii-firmware/blob/pruts/RX.cpp#L424 and the #endif after line https://github.com/koenkooi/multiwii-firmware/blob/pruts/RX.cpp#L440 should look like this:

 for (chan = 0; chan < RC_CHANS; chan++) {
#if !defined(RC_TINY)
      rcDataTmp = readRawRC(chan);
#if defined(FAILSAFE)
        failsafeGoodCondition = rcDataTmp>FAILSAFE_DETECT_TRESHOLD || chan > 3 || !f.ARMED; // update controls channel only if pulse is above FAILSAFE_DETECT_TRESHOLD
#endif // In disarmed state allow always update for easer configuration.
#if defined(SPEKTRUM) || defined(SBUS) // no averaging for Spektrum & SBUS signal
        if(failsafeGoodCondition) rcData[chan] = rcDataTmp;
#else
        if(failsafeGoodCondition) {
          rcDataMean = rcDataTmp;
          for (a=0;a<AVERAGING_ARRAY_LENGTH-1;a++) rcDataMean += rcData4Values[chan][a];
          rcDataMean = (rcDataMean+(AVERAGING_ARRAY_LENGTH/2))/AVERAGING_ARRAY_LENGTH;
          if ( rcDataMean < (uint16_t)rcData[chan] -3) rcData[chan] = rcDataMean+2;
          if ( rcDataMean > (uint16_t)rcData[chan] +3) rcData[chan] = rcDataMean-2;
          rcData4Values[chan][rc4ValuesIndex] = rcDataTmp;
        }
#endif
#endif
      if (chan<8 && rcSerialCount > 0) { // rcData comes from MSP and overrides RX Data until rcSerialCount reaches 0
        rcSerialCount --;
#if defined(FAILSAFE)
          failsafeCnt = 0;
#endif
        if (rcSerial[chan] >900) {rcData[chan] = rcSerial[chan];} // only relevant channels are overridden
      }
    }

And last but not least I think there is a bug in the failsafe code. https://github.com/koenkooi/multiwii-firmware/blob/pruts/MultiWii.cpp#L815 It should look like this (see the braces) ?!

  if ((failsafeCnt > (5*FAILSAFE_DELAY)) && f.ARMED) { 

These changes will force the copter into failsafe mode as soon as rcSerialCount reaches 0 and FAILSAFE_DELAY passed by.

I did some synthetic testing (not really flying) yesterday and it seems to be working. With this changes it should be safe to fly outside without any ceiling.

[koenkooi]

The 'pruts' and 'integration' branch should have all the changes you mentioned.

[Arne-W]

Hey KoenKooi - you are incredible fast - thank you for that!!