I dont know if you will be able to shrink marlin size that much that will fit onto an 328. But you can certainly try, you need to start removing all stuff that is not essential until you reach a compile size that fits on 328. Just in case marling is too big, you can also try with Teacup that i think has more chances to fit on 328.
In the first top part of pins.h, there is a motherboard=99 config part (untill recently when somebody else fitted =88 on top of it). The 99 its sort of "custom", you use that, just need to copy a layout and put the pins definitions according to the images above, then you should be set for testing existing functions.
The way i see it this far:
- endstops seem to be sorted already, so can leave them at that;
- A4 and A5 seem to be sda/scl? and are also analog, so those can read 2 temps either with max6675 or with thermistors;
- the spindle enable and coolant enable seem to be on a connector which can be used to take those lines into the gates of two mosfets mounted externally (on same connector there is pin 13 i think should be avoided if i recall that has a led on it?).
So imo up to here, hardware mod is fairly clear.
Something which is probably unforseen, it is enable for all motors at once. But if you dont feel comfortable you can skip this part. As a matter of choice, i would rather use one separate enable for Z, and if its possible even for E. The Z is better if its disabled when not in use, that being 90% of the time since Z is only used for layer change. E can also be disabled when not in use, but not so important as Z. To mod that, i would use pins 0 and 1 which seem to be free, to take lines to two motors at enable (after physically cutting their existing enable tracks). To have the new enable lins set as high, i would either use hardware 10k resistors pullups to 5v, or could perhaps tweak firmware and use internal pullups on those pins.
Anyway this is what i would do, this is just to show one point of view, but you can ofc choose to do everything differently :) Anyway, have fun :)
In the first top part of pins.h, there is a motherboard=99 config part (untill recently when somebody else fitted =88 on top of it). The 99 its sort of "custom", you use that, just need to copy a layout and put the pins definitions according to the images above, then you should be set for testing existing functions.
The way i see it this far:
- endstops seem to be sorted already, so can leave them at that;
- A4 and A5 seem to be sda/scl? and are also analog, so those can read 2 temps either with max6675 or with thermistors;
- the spindle enable and coolant enable seem to be on a connector which can be used to take those lines into the gates of two mosfets mounted externally (on same connector there is pin 13 i think should be avoided if i recall that has a led on it?).
So imo up to here, hardware mod is fairly clear.
Something which is probably unforseen, it is enable for all motors at once. But if you dont feel comfortable you can skip this part. As a matter of choice, i would rather use one separate enable for Z, and if its possible even for E. The Z is better if its disabled when not in use, that being 90% of the time since Z is only used for layer change. E can also be disabled when not in use, but not so important as Z. To mod that, i would use pins 0 and 1 which seem to be free, to take lines to two motors at enable (after physically cutting their existing enable tracks). To have the new enable lins set as high, i would either use hardware 10k resistors pullups to 5v, or could perhaps tweak firmware and use internal pullups on those pins.
Anyway this is what i would do, this is just to show one point of view, but you can ofc choose to do everything differently :) Anyway, have fun :)