A4988 set MSx to normally high?


I’m trying to get a Arduino CNC (cnc shield v4 with arduino nano) shield to work properly. But it seems that the shield has the MSx jumper pin connected to ground. This basically is useless since it seems that by default MSx pins are set to low, and need to be set to high to activate. I can make the micro steps work when i directly connect the driver to a breadboard and set the MSx pins to high.

My question is, can the MSx pins be changed to have default high ? this seems the be what the shield seems to be expecting. I read here and there on the web people stating that A4988 are normally high on MSx pins, but when i try it’s not the case ?


As we state on our product page for our A4988 driver boards, the MS1 and MS3 pins on the A4988 IC have internal 100kΩ pull-down resistors and MS2 has an internal 50kΩ pull-down resistor, so leaving these three microstep selection pins disconnected results in full-step mode. We are unfamiliar with the shield you mentioned, however if it also uses pull-down resistors on the MSx pins, you could connect the pins to to a logic-high voltage source like the VDD pin to bring them high. If your shield connects the pins directly to ground, you will need to disconnect them from the shield before connecting them to a logic-high voltage.



So there is no built-in feature feature to turn MSx to default high (which makes sense), i really wonder what the people who make the schematics for that arduino cnc shield were thinking. I will have to scratch the ground pcb track and re-solder them to 5v.

For anybody reading this, i would recommend to stay away from the china arduino cnc v4 shields, they seem to make a lot mistake designing their boards. I liked the idea of the compact cnc shield for arduino nano, but it requires some work to make it work properly