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10.13 Microcontroller stepper circuit with option switches

You may want to vary the ti variable in the program depending
upon your PIC crystal speed. You can experiment with the ti vari-
able until you find the best range for your particular PIC.

Troubleshooting

If the motor doesn’t move at all, check the diodes. Make sure you
have them in properly, facing in the direction shown in the
schematic.

If the stepper motor moves slightly and/or quivers back and forth,
there are a number of possible causes.
1. If you are using a battery power supply, the batteries may be
too weak to power the motor properly. Note: Batteries wear
out quickly because the current draw from stepper motors is
usually high.
2. If you substituted the TIP 120 NPN transistor for another
transistor, the substitute transistor may not be switching

Team LRN
Chapter ten