Joe's 1000x600x200 steel and aluminium router started

[devmonkey]

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.

Hi Doddy,

So it turns out if you ditch the standard I2C/TWI wire.h library and display driver, crack open the 328p datasheet, write your own crude framebuffer and I2C non-bocking state machine that operates directly on the TWI registers you can tick the state machine at a 2-3us per tick penalty. Will put it on the scope and see if this is sufficient.

Main loop becomes:
1. Mirror stepper/home signals with squaring logic.
2. Update framebuffer if needed (using a 5x7 font this is 5 memory reads/writes per character)
3. Tick I2C state machine.

I could remove the framebuffer to make it a bit faster if required, this will effectively amortise the font copy part at one byte/I2C tick.

Cheers, Joe