PCB and schematic:
Pictures of the built board:
This PCB is pretty rough around the edges, I made it a few weeks ago with the intention of etching it at home but then decided to give OSHpark a go just to see what it was like. It’s really cool. It cost 10$ delivered for three boards and they shipped to Ireland in 2 weeks from the time I ordered them. This is the first time I’ve had a silkscreen which is why the silkscreening is pretty terrible (as you can see all of the breakout pads for the motors are very helpfully labelled pad1-9) the kinks still need to be worked out. Anyways long story short the ATtiny48 uC on this board has been bricked because I didn’t know not to set the RESET DISABLE fuse with my ISP programmer. Apparently the only way to recover it is by high voltage programming and a couple other pain in the arse methods. Think this will head to the scrap bin but keep your eyes peeled for matchbox car v3 now without a matchbox (budget cuts).
Some extra info:
uC used is an ATtiny48 which has an internal 8Mhz oscillator and an ADC all for the price of 60 cent. Pretty cool.
The chips used to drive the stepper motors are LB1948MC-AH motor driver chips. These chips are nice and simple they have 4 input pins which control the 4 output pins, then there is GND and VCC. The button was going to be for disabling the motors during programming/testing.