Boat computer...

Once I am done restoring an old “project boat” I recently purchased, I plan to make it all electric. It won’t go fast, but I plan it to be very simple to operate and maintain. Part of this plan is making the boat steerable by computer. And as I already have a Raspberry Pi 3B/B+ and RISCOS is the fastest booting OS I’m aware of on that platform, I’d like to implement it as part of my plan.

Question is, has there been any attempt to control RC servos and similar (linear actuators, I believe they’re called) via the GPIO pins in RISCOS for Raspberry Pi 3?

There is a GPIO module that can control the pins. I’m not if anyone has done servo control yet or not, but if it’s just GPIO stuff I can’t see why it can’t be done.. (famous last words)

If RC servos still work the way they did when I was a kid, then you need to create a pulse-width-modulated signal. There’s a section of the GPIO to do that. The trick will be working out how to use the calls in the GPIO module to do it.

The hardware is documented in
BCM2835-ARM-Peripherals"
PWM operation starts on page 138. The registers are documented from page 90.

The GPIO help file is on the SD card in SDFS::riscospi.$.Utilities.!Manuals (hold shift down to open the last bit). It’s sparse, and in a few places wrong, but it’s all there is.