Add Channels 5-8 to Joystick Controls

[m1kelyons]

I would like to perform gain tuning and other general actions with a joystick in SIL (Taranis x9d+ as joystick on channel 5-8). What is the best way to do this? New mavlink msg or mavlink override RC?

From the SDL library, the taranis is seen as a 8-axis joystick with channels 9-32 as buttons, but channels 5-8 are not being seen in QGC as shown from Joystick.cc L547 where roll, pitch, yaw, and throttle are mapped to the joystick axes and 9-32 are passed as buttonPressedBits.

Joystick.cc : L547

emit manualControl(roll, -pitch, yaw, throttle, buttonPressedBits, _activeVehicle->joystickMode());`

The commands use the mavlink message 69 and sent in UAS.c L1020

UAS.cc : L1020

// Send the MANUAL_COMMAND message
mavlink_msg_manual_control_pack_chan(mavlink->getSystemId(),
                                     mavlink->getComponentId(),
                                     _vehicle->priorityLink()->mavlinkChannel(),
                                     &message,
                                     this->uasId,
                                     newPitchCommand, newRollCommand, newThrustCommand, newYawCommand, buttons);

I could create changes to override RC channels by creating a mavlink_msg_rc_channels_override_pack_chan function using the RC_CHANNELS_OVERRIDE mavlink message something like this...

// Send the RC_CHANNELS_OVERRIDE message
mavlink_msg_rc_channels_override_pack_chan(mavlink->getSystemId(),
                                     mavlink->getComponentId(),
                                     _vehicle->priorityLink()->mavlinkChannel(),
                                     &message,
                                     this->uasId,
                                     newChannel5Command, newChannel6Command, newChannel7Command, newChannel8Command);

OR

I could extend the MANUAL_CONTROL mavlink message and change the mavlink_msg_manual_control_pack_chan function to include the extra channels

MAVLINK common.xml : L3495

    <message id="69" name="MANUAL_CONTROL">
      <description>This message provides an API for manually controlling the vehicle using standard joystick axes nomenclature, along with a joystick-like input device. Unused axes can be disabled an buttons are also transmit as boolean values of their </description>
      <field type="uint8_t" name="target">The system to be controlled.</field>
      <field type="int16_t" name="x">X-axis, normalized to the range [-1000,1000]. A value of INT16_MAX indicates that this axis is invalid. Generally corresponds to forward(1000)-backward(-1000) movement on a joystick and the pitch of a vehicle.</field>
      <field type="int16_t" name="y">Y-axis, normalized to the range [-1000,1000]. A value of INT16_MAX indicates that this axis is invalid. Generally corresponds to left(-1000)-right(1000) movement on a joystick and the roll of a vehicle.</field>
      <field type="int16_t" name="z">Z-axis, normalized to the range [-1000,1000]. A value of INT16_MAX indicates that this axis is invalid. Generally corresponds to a separate slider movement with maximum being 1000 and minimum being -1000 on a joystick and the thrust of a vehicle. Positive values are positive thrust, negative values are negative thrust.</field>
      <field type="int16_t" name="r">R-axis, normalized to the range [-1000,1000]. A value of INT16_MAX indicates that this axis is invalid. Generally corresponds to a twisting of the joystick, with counter-clockwise being 1000 and clockwise being -1000, and the yaw of a vehicle.</field>
      <field type="uint16_t" name="buttons">A bitfield corresponding to the joystick buttons' current state, 1 for pressed, 0 for released. The lowest bit corresponds to Button 1.</field>
      <extensions/>
      <field type="int16_t" name="chan5">axis, normalized to the range [-1000,1000]. A value of INT16_MAX indicates that this axis is invalid. Corresponds to movement on joystick channel 5</field>
      <field type="int16_t" name="chan6">axis, normalized to the range [-1000,1000]. A value of INT16_MAX indicates that this axis is invalid. Corresponds to movement on joystick channel 6</field>
      <field type="int16_t" name="chan7">axis, normalized to the range [-1000,1000]. A value of INT16_MAX indicates that this axis is invalid. Corresponds to movement on joystick channel 7</field>
      <field type="int16_t" name="chan8">axis, normalized to the range [-1000,1000]. A value of INT16_MAX indicates that this axis is invalid. Corresponds to movement on joystick channel 8</field>
    </message>

Adding the extension to the MAVLINK message 69 might be the best way and then updating QGC and PX4/firmware, but wanted to post this for discussion.

Addtional info:

• GCS OS: Ubuntu 18.04 LTS
• QGC version: source commit d905745d282ee1a5a3025ca374ec25d03c7638f3
• Autopilot board: Pixhawk4
• Autopilot firmware: PX4 (custom based on v1.8.2)

[DonLakeFlyer]

This needs RC_OVERRIDE joystick which is not currently supported in QGC.

[noahbliss]

Any update?