I am trying to use an A4988 to power a Nema-17 Stepper (17HS3401) which has a rated current of 1.3A.
I realise that the current to the motor is proportional to the reference voltage V_ref, but when I use a 5V logic source, the reference voltage caps out at 0.15V when I turn the potentiometer all the way up.
Using the formula for current limiting, I get:
V_ref = I_motor * 8 * sensor_resistance.
= 1.3 * 8 * 0.068
= 0.7V
Clearly, V_ref needs to be much higher than the 0.15V my driver has capped out at.
How can I fix this issue? Is something wrong with my driver?
(I didn't have the multimeter on me to demonstrate, but I was measuring voltage difference between the potentiometer and the Arduino ground)
The Vdd pins of the A4988 are simply connected to 5V and GND of arduino.
The video I followed for this method is here:
I am very confused as to why this reference voltage is maxed out at 0.15V when the potentiometer is all the way up. Should be able to reach at least 0.7V.
If anybody could give suggestions that would be great thank you.
I am trying to use an A4988 to power a Nema-17 Stepper (17HS3401) which has a rated current of 1.3A.
I realise that the current to the motor is proportional to the reference voltage V_ref, but the reference voltage caps out at 0.15V when I turn the potentiometer all the way up.
Using the formula for current limiting, I get:
V_ref = I_motor * 8 * sensor_resistance.
= 1.3 * 8 * 0.068
= 0.7V
Clearly, V_ref needs to be much higher than the 0.15V my driver has capped out at.
I don't know what the problem is with your particular driver board, but a genuine A4988 chip cannot handle more than 1.0 A/winding, steady state. Above that it overheats and shuts down.
If you buy motor drivers from reputable suppliers like Pololu, the prices are higher, but you get genuine chips, excellent product and customer support.
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Thanks for the reply. Yeah I did buy the driver for very cheap, and might have to opt to buying a genuine Pololu one.
Is there a way I could directly measure the current to my stepper motor from the driver? There are 4 connections to the stepper from the driver, can I pass the current through my multimeter using any 1 of those 4 connections?
