Hello everyone,
I'm new to using the Arduino, so excuse me for my lack of knowledge!
I'm planning to connect my NEMA 17 to the A4988 driver, but the only thing I don't understand is the Vmot pin. The data sheet of my stepper says it needs 12 Volts, so i'm using a USB step-up converter from 5V to 12V. The datasheet of the USB-converter says when the converter is using 2-20V, the output will be 3W, so the output current of the USB will be around 250mA. So i'm wondering, is that enough for the Vmot pin, as the stepper datasheet only says it requires 12 volts and not the required amperage.
NEMA 17 tells that the mechanical mounting of the motor uses M3 screws, and a certain hole pattern......
Yo need to find out what current the stepper needs. The A4988 driver should then be set for a current in the range of the stepper.
A 3 Watt converter will most likely be way to small. It all depends of the stepper torque You need, and the current needed.
USB usually provides a maximum of 1/2 Amp. Forget using that to power the stepper.
Post the link to the stepper data sheet.
You are misinterpreting the data sheet, and a USB to 12V step-up will certainly not work to power the motor. It might even damage to the USB port.
For the A4988, you need a separate motor power supply of at least 8V, and higher is better, up to about 30V. Most laptop power supply bricks work fine, and you can get them cheaply at thrift stores.
You also need to set the current limit on the driver correctly (maximum 1 Ampere per winding, for your motor). The Pololu a4988 web page has a good connection diagram, but if you bought a cheap imitation of their A4988 driver, their instructions to set the current limit may not work for yours.
Here are the motor specs, from the data sheet linked above. Pololu's version of the A4988 is reported to be capable of providing 1 A/phase, continuously, without extra cooling.
Who knows what the cheap knockoffs can handle, even if the chips are genuine?
1.8 deg. step angle(200 steps/rev), Rated current 1.0 A & resistance 3.5ohms.
Hello all,
Thanks for all your quick answers!
As jremington advised me earlier, I bought a separate power supply brick which should be able to deliver the required voltage.
Just FYI, I have the pololu A4988 and not a knockoff, so indeed it is 1 A/phase, so it should be all right!
I bought some extra heat sinks for safety, even though the A4988 doesn't have to reach 1A/phase
