Created
January 9, 2017 08:24
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A demo of using a rotary encoder with raspberry pi
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| import RPi.GPIO as GPIO | |
| import time | |
| # Pin definition | |
| pwm_pin = 18 # adjust brightness for signal | |
| led_pin = 23 # blink when switch pressed | |
| clk_pin = 14 # rotary clock | |
| but_pin = 24 # button input | |
| dat_pin = 25 # rotary data input | |
| DUTY_CYCLE = 50 # initial duty cycle | |
| DUTY_STEP = 10 # increments for pwm | |
| # Pin Setup | |
| GPIO.setmode(GPIO.BCM) # Broadcom numbering | |
| GPIO.setup(led_pin, GPIO.OUT) | |
| GPIO.setup(pwm_pin, GPIO.OUT) | |
| pwm = GPIO.PWM(pwm_pin, 50) # initialize pwm led | |
| GPIO.setup(but_pin, GPIO.IN, GPIO.PUD_UP) | |
| GPIO.setup(clk_pin, GPIO.IN, GPIO.PUD_UP) | |
| GPIO.setup(dat_pin, GPIO.IN, GPIO.PUD_UP) | |
| pwm.start(DUTY_CYCLE) | |
| def set_duty(value): | |
| """Limit duty range to 0-100""" | |
| global DUTY_CYCLE | |
| if value > 100: | |
| value = 100 | |
| elif value < 0: | |
| value = 0 | |
| DUTY_CYCLE = value | |
| #print('New Brighness: %s' % DUTY_CYCLE) | |
| pwm.ChangeDutyCycle(DUTY_CYCLE) | |
| def rotary_on_change(channel): | |
| """Called whenever the encoder moves""" | |
| global DUTY_CYCLE | |
| #print('Old Brighness: %s' % DUTY_CYCLE) | |
| if GPIO.input(dat_pin): #forward | |
| #print("Going up") | |
| set_duty(DUTY_CYCLE + DUTY_STEP) | |
| else: # rotate backward | |
| #print("Going down") | |
| set_duty(DUTY_CYCLE - DUTY_STEP) | |
| def blink_led(channel=None): | |
| """uh... make it blink""" | |
| GPIO.output(led_pin, GPIO.HIGH) | |
| time.sleep(0.075) | |
| GPIO.output(led_pin, GPIO.LOW) | |
| time.sleep(0.075) | |
| print("Here we go! Press CTRL+C to exit") | |
| try: | |
| GPIO.output(led_pin, GPIO.LOW) | |
| # configure rotary callback | |
| GPIO.add_event_detect(clk_pin, | |
| GPIO.FALLING, | |
| callback=rotary_on_change, | |
| bouncetime=200) | |
| # configure button callback | |
| GPIO.add_event_detect(but_pin, | |
| GPIO.FALLING, | |
| callback=blink_led, | |
| bouncetime=200) | |
| # main loop | |
| while 1: | |
| print("Current Brightness: %s" % DUTY_CYCLE) | |
| time.sleep(1) | |
| except KeyboardInterrupt: # Catch CTRL+C and clean up | |
| pwm.stop() | |
| GPIO.cleanup() |
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