Enable 32 servos

[srmainwaring]

Enable 32 servos when the parameter SERVO_32_ENABLE is set.

This PR is the companion to https://github.com/ArduPilot/ardupilot/pull/23239 for the ArduPilot gazebo plugin.

Details

• Add optional boolean plugin parameter <have_32_channels> to enable 32 rather than 16 channels.
• Add new struct for the servo packet with 32 channels and new magic number matching SITL_JSON.
• Modify UpdateMotor commands to accept a std::array of PWMs rather than the entire servo packet.
• Update ReceiveServoPacket to receive either 16 or 32 channel servo packet depending on the plugin parameter <have_32_channels>.

Testing

Testing with iris_runway.sdf world:

Gazebo

gz sim -v4 -r iris_runway.sdf

SITL

sim_vehicle.py -D -v ArduCopter -f gazebo-iris --model JSON  --console

Enable 32 servos

Enable 32 servos in MAVProxy:

Magic number for 32 channel servo packet received:

Update plugin parameter and restart and the connection is restored.

<plugin name="ArduPilotPlugin"
  filename="libArduPilotPlugin">
  <!-- Port settings -->
  <fdm_addr>127.0.0.1</fdm_addr>
  <fdm_port_in>9002</fdm_port_in>
  <connectionTimeoutMaxCount>5</connectionTimeoutMaxCount>
  <lock_step>1</lock_step>
  <have_32_channels>1</have_32_channels>
  ...
</plugin>

Disable 32 servos

Magic number for 16 channel servo packet received:

Update plugin parameter and restart and the connection is restored.

<plugin name="ArduPilotPlugin"
  filename="libArduPilotPlugin">
  <!-- Port settings -->
  <fdm_addr>127.0.0.1</fdm_addr>
  <fdm_port_in>9002</fdm_port_in>
  <connectionTimeoutMaxCount>5</connectionTimeoutMaxCount>
  <lock_step>1</lock_step>
  <have_32_channels>0</have_32_channels>
  ...
</plugin>

[srmainwaring]

Tested during review of https://github.com/ArduPilot/SITL_Models/pull/96.