I am stuck with a problem. I am trying to control 2 stepper motors (Nema 17 1,7Amps) wired together at the same port with Arduino extended with Arduino shield and A4988 driver.
I am using GRBL firmware and I had no problem controlling just one motor but now with 2 motors they have no strength and loses steps. At the beginning I thought that it was a powering problem but now I am using a 12V 30 Amps power supply and nothing changed.
My question is … there is some settings that I have to change in the firmware to control 2 motors in this way? Or am I doing wrong something else?
My instant guess is that you can't drive two parallel coils through one output of the stepper driver. When the coils are powered, the resistive inductance of the coils somehow disturb each other.
Or have you connected the motors in series?
If you connect the motor coils in series the same current (as set by the A4988) will flow through both motors.
Please post a link to the datasheet for your motors. A higher voltage power supply may be needed.
If the motors are connected in parallel they will need twice the current but the A4988 may only be set for the current for a single motor and may not actually be able to provide enough current for two motors in parallel.
I have a RAMPS cnc shield that has connections for two Z motors (presumably in parallel) but I have never had any reason to try two motors.
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