Quote Originally Posted by Doddy View Post
Interested to see how this goes. Glad to hear you're bit-banging, though as the 328 is inline with the axis pulses to the stepper drivers it has to keep up at all time (not just homing) and I'd be curious if you can hold the signalling whilst I2Cing the display - interesting challenge.

I did realise after writing that the optos were for homing switches/reflection into the DDCS, so, yeah, will be fine - I'll withdraw that.
Yeh the I2C is the dubious part, albeit it is done in hardware, I haven't coded that yet, if it gets in the way it can be omitted. I just usually add them to all my boards these days as I have a drawer full and they only cost a few quid. In this case I had disable the uart to use the rx/tx pins for outputs so without I2C there is no way to get any debug out whilst testing. I did this so I could get a full 8 bit synchronous port write to the drivers rather that making multiple consecutive writes. Every true IO pin is in use ;-)