I’ve been playing with the A4983 stepper driver (#1201), the 10V bipolar stepper motor (#1208), and an Arduino Duemilanove.
When I wired up the attached configuration, with the DIR and STEP pins empty, the stepper motor begins to get really hot. The motor shaft is also locked up. There is 10V across each of the coil pairs on the motor (1A-1B and 2A-2B).
I just wanted to ask if this was normal. Is the default of the A4983 to put current through the motor and lock it up?
That is indeed the default behavior; you can use the reset pin if you want to turn off power to the motor. In many stepper motor applications, you want to keep track of position, which you could more readily lose if you stop powering the motor. If you don’t need the full torque that the motor can provide, you can lower the current limit on the driver, which will lower how much everything heats up.
Ok, so if I’m reading the datasheet correctly, to cut power to the motor I need to set the RES pin to low? To bring power back to the motor, I need to set the RES pin to high?
You are right about what you say, and the reset pin turns off more than just the power to the motors. Reseting the chip turns it off entirely including the memory of which microstep it was on. You might want to investigate the differences between Enable and Reset.