Why use or implement a DC/stepper motor controller? Is it not possible to connect the motor directly to an MCU output pin without the driver?
Electronic – Why use stepper/DC motor driver
dc motordrivermicrocontrollerstepper motor
Related Solutions
Is your project the stepper motor driver, or is this for another, larger project?
Unless you specifically want to learn about the intricacies of driving stepper motors, I would recommend just buying an off-the-shell stepper driver, either in IC form, or completely assembled.
I'm a big fan of the Allegro Micro stepper drivers.
If you want a simple, off-the-shelf solution, spark run offers a couple really inexpensive stepper-driver boards (seriously, they pretty much cost as much as the equivalent parts).
(Images are links)
They would be quite simple to interface with your USB DAQ system too. It would just take two DIO lines. One would set the direction, and the other would cause the motor to step - one step per cycle.
There are many companies who do do dedicated chips for stepper drivers. The A4988 has a step+dir digital interface. If that's what you want, then you could for example use the Texas Instruments' DRV8825
I was myself looking at different ways of interfacing stepper motors (not just step+dir), and made a comparison table of stepper motor drivers.
Best Answer
A microcontroller has a very low output current. You shouldn't drive directly more than an usual indicator LED with it.
The motor draws a much higher current. Connecting directly will result in not working motor and destroying the microcontroller due to high currents.
Drivers are not used only for motors. They are used for any device that usually draws more than 50-100 mA.