The next module I want to make is the Servo Module. This is handy since the 16 channels also can be used as digital/analogue IO signals.
I will use 16 x 3xRight Angle Headers and some jumpers to select between voltage. I will only support 5V & 12V and max 10A in total. Higher voltage or effects will need to get their power directly.
Supporting 16 channels this way is a bit much as the total current usage can be quite high so I will add current sensors to monitor usage. I also need an inductor to prevent pulses from going back to the backplane. I need to review the 5V here because we currently only have a single 5V supply that also is used for the MCU. I probably need to add a 2nd 5V on the backbone to allow for separate PSU’s for modules connected to actuator/servos.
In this case we also need to feed the 3.3V MCU from the 5V/12V used for the servo’s as we otherwise might not have a ground to our signal. Communication with backbone is RS-485 based on differential siganaling not depending on anything but those two wires, so this will work fine. It also means that we will no connect to the 5V MCU/Ground at all on this module. This actually raises a question if I should switch to isolated RS-485 towards the backplane here.