Photoresistor

Changes its electrical resistance in response to light intensity. Can be used to detect changes in light intensity.

Learn how to make your own photoresistor here.

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Basic photo resistor example

# --- Imports
import time
import board
import analogio

# --- Variables
# Initialize analog input connected to photo resistor
photo_resistor = analogio.AnalogIn(board.A2)

# --- Functions

# --- Setup

# --- Main loop
while True:
    val = photo_resistor.value # Read the photo resistor value
    print(val) # Output the value in the serial monitor
    time.sleep(0.05)  # Make the loop run a little bit slower

Photo resistor example with conversion to voltage

# --- Imports
import time
import board
import analogio

# --- Variables
# Initialize analog input connected to photo resistor
photo_resistor = analogio.AnalogIn(board.A2)

# --- Functions
# Make a function to convert from analog value to voltage.
def analog_voltage(adc):
    return adc.value / 65535 * adc.reference_voltage

# --- Setup

# --- Main loop
while True:
    val = photo_resistor.value # Read the photo resistor value
    volts = analog_voltage(photo_resistor) # Convert to voltage

    # Print the values
    print('Photo resistor value: {0} voltage: {1}V'.format(val, volts))
    time.sleep(0.05)  # Make the loop run a little bit slower