Hello, i want to find a easy solution to stop motors with external circuit in parallel ,my idea is just to link pwm signal with mosfet or transistor to the ground , I wonder if it might not destroy the pixhawk , in piaxhawk 1 hardware there is 220 ohms resistor in series with the outputs , i can not find the pixhawak 4 detailed hardware ,it should be the same thing and it can work , I want your idea on the subject
Why don’t you use Emergency Stop feature provided by Ardupilot? It would be the simplest way to do that and you wouldn’t need any kind of extra hardware:
I can testify that the Motor Emergency Stop feature definitely works as planned.
If you really need some external device, you would probably need to use some circuit with a 74LS244 or similar to properly pass the PWM signals (or disable them). Your idea of shorting the PWM outputs to ground may work but would need testing.
it is for a specific regulation, they ask for an independent parachute with an independent engine cut-off.
I have already designed and tested components (mux) which connect in series with the pwm output, it works well but if the component fails there is a big risk, I am thinking of a simpler solution and more reliable which connects in prallel and can be detached from the main circuit that’s where my idea comes from.