A4988 on a Mightyboard setting Step Resolution - Help Please

I’m attempting to replace 1stepper driver on a Mightyboard with a A4988 to which I will solder the pins.

As you probably know the pins on the A4988 carrier board as fitted to a mightyboard are inverted, the chip is on the pin side of the carrier. Good fun that’s were the potentiometer is going to be but that’s another issue.

According to ReplicatorG Sailfish 7.7 directly references microstepping at a resolution of 1/8 so I’d like to set the driver to 1/8 stepping.

The only “how to” I’ve found requires that I don’t fit the MS3 pin and bridge MS2 to MS3 with a blob of solder this will apparently give a resolution of 1/16 stepping.

Apparently for 1/8 I need :-

MS1 high,… MS2 high,… MS3 low … and if they are all high then I get 1/16 stepping

What would I need to do to set a 1/8 stepping?

So if I don’t bridge MS2 to MS3 will MS3 be low?

Or I could ground MS3 with a short wire to one of the ground pins but that’s a risk I might try something.

Thanks All. Aamcle

Hello, Aamcle.

For our A4988 carriers, the signals needed for 1/8th microstepping are shown in the micro-stepping table in the “Step (and microstep) size” section of its product page. MS1 and MS2 should be high and MS3 should be low (your GND connection should be fine to pull that pin low).

If you need additional help, can you post some pictures of your A4988 carrier in its setup?


Many thanks. Aamcle