wvreeven wrote: The ST4 connector is meant to connect the guide camera to the mount so it can forward guide pulses to the mount. It requires the guide camera to be connected to the PI using an USB cable.

HTH, Wouter

Unfortunately my camera doesn't have a guide port.

I had been looking at using PHD2 on my laptop and using a USB to ST-4 adaptor but I can't find any information to say that it works on the Pi.

In case it doesn't work I was wondering if there was any other approach, such as opto-isolated GPIO, that would work with Astroberry?