DougieLawson wrote: ↑
Mon Mar 02, 2015 11:28 am
The ULN2003 isn't a driver chip, it's a buffer chip (it only prevents back EMF).
Actually it's a darlington array commonly supplied with cheap unipolar stepper motors.
The switch higher currents and voltages when driven with very low current an voltage from gpio pins. They also have flyback diodes to protect against back EMF.
You control the stepper by turing on the four gpio driving the inputs to the darlington array in the proper sequence.
It works fine but the coding a little bit more involved than with a pulse and direction stepstick type driver.
Here is a tutorial using similar ULN2803 / L293D darlington arrays.
ULN2003A functions the same way but note the different package.
https://learn.adafruit.com/adafruits-ra ... s/overview