For the Winter 2009 offering of the University of Washington CSE Software for Embedded Systems course, I designed a laboratory assignment around electric field sensing. In the lab, students used an 8-bit microcontroller to accomplish the following:
- generate a waveform at a specific frequency to drive a resonant transmitter
- synchronously sample a received signal with an analog/digital converter
- demodulate the received signal in software to recover the signal magnitude
- use pulse-width modulation to drive an RGB LED, varying its color with the sensed distance between the sensor and the user’s hand