Zeroplus Arduino starter kit with Logic Analyzer Manual page 58

DESCRIPTION
A photoresistor is a resistor whose value varies when exposed to
light. In this experiment we visualize in ZP Studio the variation
of light sensed by the photoresistor. Because the logic analyzer
captures only digital signals only and the sensor outputs an analog
signal, we have to convert this analog signal into a digital signal
that can be acquired by the logic analyzer. The analog-digital
conversion is handled by an ADC (Analog to Digital Converter)
embedded on the Arduino board. All we need to do is to get this
value, break it down into several bits and distribute them between
the pins of the Arduino. That's what the source code provided does.