Page 247 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

the program halts the stepper motor and stays in a holding loop for
as long as SW3 is closed (or pressed). Rotation direction, CW or
CCW, is controlled with SW4. Pressing SW4 reverses the stepper
motor direction. The direction stays in reverse for as long as SW4
is pressed (or closed).
‘Stepper motor controller
Symbol TRISB = 134 ‘Initialize TRISB to 134
Symbol TRISA = 133 ‘Initialize TRISA to 133
Symbol PortB = 6 ‘Initialize portb to 6
Symbol PortA = 5 ‘Initialize porta to 5
symbol ti = b6 ‘Initial ti delay
ti = 100 ‘Set delay to 100 ms
Poke TRISB,0 ‘Set PORTB lines output
start: ‘Forward stepper motor rotation sequence
poke portb,1 ‘Step 1
pause ti ‘Delay
poke portb,2 ‘Step 2
pause ti ‘Delay
poke portb,4 ‘Step 3
pause ti ‘Delay
poke portb,8 ‘Step 4
226 pause ti ‘Delay
goto check ‘Jump to check switch status
start2: ‘Reverse motor rotation sequence
poke portb,8 ‘Step 1
pause ti ‘Delay
poke portb,4 ‘Step 2
pause ti ‘Delay
poke portb,2 ‘Step 3
pause ti ‘Delay
poke portb,1 ‘Step 4
pause ti ‘Delay
goto check ‘Jump to check switch status
Check: ‘Switch status
Peek PortA, B0 ‘Peek the switches
If bit0 = 0 then loop1 ‘If SW1 is closed, increase ti
if bit1 = 0 then loop2 ‘If SW2 is closed, decrease ti
if bit2 = 0 then hold3 ‘Stop motor
if bit3 = 0 then start ‘Go forward
goto start2 ‘Go reverse
loop1: ‘Increase delay
poke portb,0 ‘Turn off transistors
ti = ti + 5 ‘Increase delay by 5 ms
pause 50 ‘Delay
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Chapter ten