Serial Servo PWM expansion board

Hardware Other Hardware
1

Hello,

For a VTOL project I would need to add PWM ports to a Kakute F7 AIO board.

A while ago I made a firmware for Arduino Mini based on the AP_RC library.
It uses a home made protocol and the HDLC transport layer.

I was quite happy with this expansion board and today I could reuse it as it is.
But then I would have to add my protocol and library to ArduPilot, and I suspect the effort would be a waste of time.

I once used the Pololu serial to PWM boards but I don’t have them at hand now, and I am not aware of any use case with Ardupilot.

I am now leaning toward making a firmware which uses the MAVLink protocol to request the MAV_DATA_STREAM_RC_CHANNELS stream.
The board I plan to use is an Arduino Pro Mini

I am starting to read this topic :
https://discuss.ardupilot.org/t/mavlink-and-arduino-step-by-step/25566

My questions are :

  • Are there any similar and adopted project, namely using serial ports to expand the PWM ports on an autopilot HW, and ideally using an arduino board and MAVLink ?
  • Any suggestion about I could add PWM ports to a limited HW ?

Thanks, be safe at home :slight_smile:

2

It is possible to get two extra PWM outs with a small code change, that get you to 8.

We support subs ouput over uart, you can then just buy a decoder.

https://ardupilot.org/plane/docs/common-sbus-out.html?sbus-to-pwm-decoders#sbus-to-pwm-decoders

1 Like
3

Thanks @iampete !

This is awesome and exactly what I needed.
Actually I would need only one extra servo on the Kakute so I could use the LED Pin as is.

Thanks for your work and suggestion !

As for the Sbus decoder, package delivery is a bit tricky these days.
Maybe in the future I could make a firmware that use MAVLink to output PWM on an arduino.
But for now I will stay focused on the existing pile of projects.