More detail on reading varying voltage inputs.
0:00 Wiring an FSR (force sensitive resistor)
2:09 Measuring it's resistance using a Multimeter
3:24 Wiring a photocell to measure light
4:59 Read from analog pins using analogRead()
6:42 Overview of analog-to-digital converstion (ADC)
9:21 Use map() to detect the sensor's state