Datasheet

At this point you can read the value property to get a reading of the light seen by the photocell. Try it:

Try covering the photocell with your hand to block the light it can see and read the value again:

Notice the value changed! When the sensor sees less light the value is reduced. The more light the sensor sees, the

higher the value.

You might wonder, what's the range of possible values? It turns out for an analog input in CircuitPython the maximum

values range from 0 to 65535 (or the maximum 16-bit unsigned integer value). If you shine an extremely bright light on

the photocell you might see a value near 65k, and if you completely block the sensor you might see a value down

near 0.

If you're curious you can also convert this value into a voltage that's higher or lower depending on how much light is

hitting the sensor. Let's make a function to do this:

Cool! Notice the voltage increases up to near 3.3 volts as the light hitting the photocell increases. If you cover the

photocell up and read the voltage you'll see it falls down near 0 volts.

You can use either the raw value or voltage to check how much light is hitting the photocell. Both will change

proportionally to the amount of light hitting the sensor.

photocell = analogio.AnalogIn(board.A1)

photocell.value

def analog_voltage(adc):

return adc.value / 65535 * adc.reference_voltage

volts = analog_voltage(photocell)

print('Photocell voltage: {0}V'.format(volts))