This might be a really simple / stupid question:
On the BED, there is three terminals (M1, M2 and M3) which decides the microstep settings. They have internal pullups (20K). To change microstep setting, I tie one or more to ground depending on what setup I want.
If I dont connect them to ground, but to the Arduino's digital pin (output), would it be possible to adjust microstep settings by setting the digital output either HIGH or LOW?