Friday, March 19, 2010
I bought the phidgets 0/16/16 board and then discovered I could not reverse polarity for stepper motor driving, although the board could handle the current: 2A drivers are already on the board. So I added the L298N H-bridge and a slew of too many parts. The current regulator is LM317T with 0.77 ohms across the input to limit the current draw to 1.6 Amps. You can find the wiring diagrams with the datasheets for those chips. The bipolar motor has four wires. The phidgets output block uses two direction outputs and two coil-enable output wires to control the two bipolar motor coils. I used 1500 ohm pull-up resistors on the L298 inputs. So the phidgets is actually disabling (grounding) those inputs by turning ON the phidgets output. I wish I bought a stepper add on board. It would have been easier. Here is one: www.robotshop.ca
http://www.youtube.com/watch?v=8OrnzUotS_Y&hl=en
