Photoresistor is a commonly used component of ambient light intensity in life. It helps the controller to recognize day and night and realize light control functions such as night lamp. This project is very similar to potentiometer, and you might think it changing the voltage to sensing light.
Step 1: Build the circuit.
Step 2: Go to the folder of the code.
Step 3: Run the executable file.
sudo python3 2.2.1_Photoresistor.py
When the code is running, the brightness of the LED will change according to the light intensity sensed by the photoresistor.
You can Modify/Reset/Copy/Run/Stop the code below. But before that, you need to go to source code path like
raphael-kit/python. After modifying the code, you can run it directly to see the effect.
#!/usr/bin/env python3 import RPi.GPIO as GPIO import ADC0834 import time LedPin = 22 def setup(): global led_val # Set the GPIO modes to BCM Numbering GPIO.setmode(GPIO.BCM) # Set all LedPin's mode to output and initial level to High(3.3v) GPIO.setup(LedPin, GPIO.OUT, initial=GPIO.HIGH) ADC0834.setup() # Set led as pwm channel and frequece to 2KHz led_val = GPIO.PWM(LedPin, 2000) # Set all begin with value 0 led_val.start(0) def destroy(): # Stop all pwm channel led_val.stop() # Release resource GPIO.cleanup() def loop(): while True: analogVal = ADC0834.getResult() print ('analog value = %d' % analogVal) led_val.ChangeDutyCycle(analogVal*100/255) time.sleep(0.2) if __name__ == '__main__': setup() try: loop() except KeyboardInterrupt: # When 'Ctrl+C' is pressed, the program destroy() will be executed. destroy()
def loop(): while True: analogVal = ADC0834.getResult() print ('analog value = %d' % analogVal) led_val.ChangeDutyCycle(analogVal*100/255) time.sleep(0.2)
Read the analog value of CH0 of ADC0834. By default, the function
getResult() is used to read the value of CH0, so if you want to read
other channels, please input 1, 2, or 3 into () of the function
getResult(). Next, what you need is to print the value via the print
function. Because the changing element is the duty cycle of
analogVal*100/255 is needed to convert analogVal
into percentage. Finally,
ChangeDutyCycle() is called to write the