Bitcraze Forums

Posted: **Tue Apr 12, 2022 10:18 am**

Dear Bitcraze,

we would like to use CPPM Receiver with Position Hold for our Application, therefore we are using the Flowdeck for that.
While flying with Crazy Radio the Position Hold works flawlessly, I can't figure out how to use Position Hold with CPPM Input though.

What can I do to configure Channel 5 or 6 of the CPPM Lib ( extra.c) to activate Position Hold (through Optical Flow / FlowDeck)?

Thank you in Advance.

4things

Posted: **Wed Apr 13, 2022 12:55 pm**

Easiest is probably if you rewrite the ALT hold part and change it to Position hold. This mode is the hoverDecoder in crtp_commander_generic.c. You would have to scale the CPPM input properly.

Without testing it, I think it would look something like this:

Code: Select all

  if (extRxAltHold) 
  {
    extrxSetpoint.thrust = 0;
    extrxSetpoint.mode.z = modeVelocity;

    extrxSetpoint.velocity.z = cppmConvert2Float(ch[EXTRX_CH_THRUST], -1, 1, EXTRX_DEADBAND_ZVEL);
    
    
    extrxSetpoint->mode.yaw = modeVelocity;
    extrxSetpoint->attitudeRate.yaw = EXTRX_SIGN_YAW * EXTRX_SCALE_YAW *cppmConvert2Float(ch[EXTRX_CH_YAW], -1, 1, EXTRX_DEADBAND_YAW);
    
    
    extrxSetpoint->mode.x = modeVelocity;
    extrxSetpoint->mode.y = modeVelocity;
    extrxSetpoint->velocity.x = cppmConvert2Float(ch[EXTRX_CH_ROLL], -1, 1, EXTRX_DEADBAND_ZVEL);
    extrxSetpoint->velocity.y = cppmConvert2Float(ch[EXTRX_CH_PITCH], -1, 1, EXTRX_DEADBAND_ZVEL);
    
    extrxSetpoint->velocity_body = true;
  } 
  else 
  {
    extrxSetpoint.mode.z = modeDisable;
    extrxSetpoint.thrust = cppmConvert2uint16(ch[EXTRX_CH_THRUST]);

    extrxSetpoint.attitude.roll = EXTRX_SIGN_ROLL * EXTRX_SCALE_ROLL * cppmConvert2Float(ch[EXTRX_CH_ROLL], -1, 1, EXTRX_DEADBAND_ROLL);
    extrxSetpoint.attitude.pitch = EXTRX_SIGN_PITCH * EXTRX_SCALE_PITCH * cppmConvert2Float(ch[EXTRX_CH_PITCH], -1, 1, EXTRX_DEADBAND_PITCH);
    extrxSetpoint.attitudeRate.yaw = EXTRX_SIGN_YAW * EXTRX_SCALE_YAW *cppmConvert2Float(ch[EXTRX_CH_YAW], -1, 1, EXTRX_DEADBAND_YAW);
  }
  
  extRxAltHoldPrev = extRxAltHold;
  
  #else
  extrxSetpoint.mode.z = modeDisable;
  extrxSetpoint.thrust = cppmConvert2uint16(ch[EXTRX_CH_THRUST]);
  extrxSetpoint.attitude.roll = EXTRX_SIGN_ROLL * EXTRX_SCALE_ROLL * cppmConvert2Float(ch[EXTRX_CH_ROLL], -1, 1, EXTRX_DEADBAND_ROLL);
  extrxSetpoint.attitude.pitch = EXTRX_SIGN_PITCH * EXTRX_SCALE_PITCH * cppmConvert2Float(ch[EXTRX_CH_PITCH], -1, 1, EXTRX_DEADBAND_PITCH);
  extrxSetpoint.attitudeRate.yaw = EXTRX_SIGN_YAW * EXTRX_SCALE_YAW *cppmConvert2Float(ch[EXTRX_CH_YAW], -1, 1, EXTRX_DEADBAND_YAW);
  #endif
  
  commanderSetSetpoint(&extrxSetpoint, COMMANDER_PRIORITY_EXTRX);

Posted: **Mon Apr 18, 2022 4:06 pm**

thank you so much that worked perfectly.

only one change need to be done

Code: Select all

extrxSetpoint.velocity.x = cppmConvert2Float(ch[EXTRX_CH_ROLL], -1, 1, EXTRX_DEADBAND_ZVEL);
extrxSetpoint.velocity.y = cppmConvert2Float(ch[EXTRX_CH_PITCH], -1, 1, EXTRX_DEADBAND_ZVEL);

needs to be changed to

Code: Select all

extrxSetpoint.velocity.y = cppmConvert2Float(ch[EXTRX_CH_ROLL], -1, 1, EXTRX_DEADBAND_ZVEL);
extrxSetpoint.velocity.x = cppmConvert2Float(ch[EXTRX_CH_PITCH], -1, 1, EXTRX_DEADBAND_ZVEL);

the whole change to extrx.c (https://github.com/bitcraze/crazyflie-f ... trx.c#L202:

Code: Select all

  if (extRxAltHold) 
  {
    extrxSetpoint.thrust = 0;
    extrxSetpoint.mode.z = modeVelocity;

    extrxSetpoint.velocity.z = cppmConvert2Float(ch[EXTRX_CH_THRUST], -1, 1, EXTRX_DEADBAND_ZVEL);
    
    
    extrxSetpoint->mode.yaw = modeVelocity;
    extrxSetpoint->attitudeRate.yaw = EXTRX_SIGN_YAW * EXTRX_SCALE_YAW *cppmConvert2Float(ch[EXTRX_CH_YAW], -1, 1, EXTRX_DEADBAND_YAW);
    
    
    extrxSetpoint->mode.x = modeVelocity;
    extrxSetpoint->mode.y = modeVelocity;
    extrxSetpoint->velocity.y = cppmConvert2Float(ch[EXTRX_CH_ROLL], -1, 1, EXTRX_DEADBAND_ZVEL);
    extrxSetpoint->velocity.x = cppmConvert2Float(ch[EXTRX_CH_PITCH], -1, 1, EXTRX_DEADBAND_ZVEL);
    
    extrxSetpoint->velocity_body = true;
  } 
  else 
  {
    extrxSetpoint.mode.z = modeDisable;
    extrxSetpoint.thrust = cppmConvert2uint16(ch[EXTRX_CH_THRUST]);

    extrxSetpoint.attitude.roll = EXTRX_SIGN_ROLL * EXTRX_SCALE_ROLL * cppmConvert2Float(ch[EXTRX_CH_ROLL], -1, 1, EXTRX_DEADBAND_ROLL);
    extrxSetpoint.attitude.pitch = EXTRX_SIGN_PITCH * EXTRX_SCALE_PITCH * cppmConvert2Float(ch[EXTRX_CH_PITCH], -1, 1, EXTRX_DEADBAND_PITCH);
    extrxSetpoint.attitudeRate.yaw = EXTRX_SIGN_YAW * EXTRX_SCALE_YAW *cppmConvert2Float(ch[EXTRX_CH_YAW], -1, 1, EXTRX_DEADBAND_YAW);
  }
  
  extRxAltHoldPrev = extRxAltHold;
  
  #else
  extrxSetpoint.mode.z = modeDisable;
  extrxSetpoint.thrust = cppmConvert2uint16(ch[EXTRX_CH_THRUST]);
  extrxSetpoint.attitude.roll = EXTRX_SIGN_ROLL * EXTRX_SCALE_ROLL * cppmConvert2Float(ch[EXTRX_CH_ROLL], -1, 1, EXTRX_DEADBAND_ROLL);
  extrxSetpoint.attitude.pitch = EXTRX_SIGN_PITCH * EXTRX_SCALE_PITCH * cppmConvert2Float(ch[EXTRX_CH_PITCH], -1, 1, EXTRX_DEADBAND_PITCH);
  extrxSetpoint.attitudeRate.yaw = EXTRX_SIGN_YAW * EXTRX_SCALE_YAW *cppmConvert2Float(ch[EXTRX_CH_YAW], -1, 1, EXTRX_DEADBAND_YAW);
  #endif
  
  commanderSetSetpoint(&extrxSetpoint, COMMANDER_PRIORITY_EXTRX);

Bitcraze Forums

Position Hold with Flowdeck and CPPM input

Position Hold with Flowdeck and CPPM input

Re: Position Hold with Flowdeck and CPPM input

Re: Position Hold with Flowdeck and CPPM input