Hi,
I connected a PIC16F84 to a ULN2803 5volt driver to a 5volt 6-wire stepper motor. The motor was running for about 20 seconds, then stopped and it will not start again. Even if I turn off power and turn it back on.
Here is my code to control / pulse the stepper motor.
Attached is my schematic. Any idea why it would quit and then not work again?
Jen
start
movlw 0x00
tris PORTA
loop
movlw b'00000101'
movwf PORTA
call DELAY_20
movlw b'00001001'
movwf PORTA
call DELAY_20
movlw b'00001010'
movwf PORTA
call DELAY_20
movlw b'00000110'
movwf PORTA
call DELAY_20
goto loop
Forgot to mention to try with the other 4 transistors of the ULN array.. if they motor moves like normal immediately turn the power off so you dont kill the transistors..!
You don't have current limiting resistors at the input to the ULN. The PIC can output 20mA minimum, the max is not specified. Perhaps the base-emitter junction is fried, use your diode checker to see if the ULN input still looks like a diode.
You don't have current limiting resistors at the input to the ULN. The PIC can output 20mA minimum, the max is not specified. Perhaps the base-emitter junction is fried, use your diode checker to see if the ULN input still looks like a diode.
Sorry... Actually, yes I do have it grounded. I just neglected to put in the gnds on the schematic to speed things up for posting the picture. Yes, it was very weird, it worked for a while then stopped, I reprogrammed the PIC with some updated code and tried it again and it worked for about 20-30 seconds then stopped and didn't go again.
Any other ideas?
Jen
also make sure your leads are in the correct order ... you may also want to slow down the pace of your steps a little, try increasing the delay between each step.