I got a new MKS 1.4 controller board and it came with A4988 driver chips. But I can't figure out which way they install. I found something saying to match the printing on the back of the chip to that on the board. But I don't see anything that matches. Suggestions?

Rear of A4988 breakout board

Close up of MKS 1.4 A4988 socket

  • $\begingroup$ You might be able to figure this out with a multimeter. The 1A/2A/1B/2B pins should have continuity to the connectors for the motors. $\endgroup$ Jan 23, 2017 at 8:16
  • $\begingroup$ Thanks - I found a pin diagram last night that indicates the same. $\endgroup$ Jan 23, 2017 at 13:01
  • 1
    $\begingroup$ In that case, consider writing an answer to your own question, so that the next person who finds this question via google actually finds an answer here. $\endgroup$ Jan 23, 2017 at 13:09
  • $\begingroup$ Will do, as soon as I can confirm it. $\endgroup$ Jan 23, 2017 at 15:59
  • $\begingroup$ If this is the same board as MKS GEN, then this page should help: reprap.org/wiki/MKS_GEN $\endgroup$
    – Mikhail Z
    May 29, 2017 at 21:35

3 Answers 3


From A4988 Stepper Motor Driver Carrier, the rear of the breakout board, is identical to yours:

A4988 Breakout rear

Note the two square pads for the GND, whereas the others are round. Now looking at the top side:

A4988 Breakout top

and note the position of the square GND pins/pads, in relation to the trim pot.

Now look at this hi-res photo of a populated MKS board

MKS controller with A4988 drivers fitted

Again, looking at the position of the trim pots, one can see that the A4988 breakout boards need to be oriented such that the side with GND pins need to be nearest to the top of the board. That is to say the GND on the corner of the breakout board, needs to be pointing North East, as it were.

Here is a schematic of the MKS 1.4 as well, although it is not much use, from MKS Gen 1.4 circuit and pinouts:



I´ve seen some cards using A4988, and also I have designed my own cards and the most and useful pin arrangement is V Mot, GND, 2B 2A 1A 1B VDD GND, so stepper motor is conected close to 2B 2A 1A 1B.

Never place this pinout oposite side to stepper connectors. Stepper connector are marked as X, Y, Z, E0, E1.

The assembly picture from Ali express is correct.


The below image was taken from their AliExpress shop page.

Unfortunately, I don't manage to find the datasheet or schematic to give more technical advice.

enter image description here


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