Tue Dec 11 11:17:14 CET 2007

driving led

driving the led during reception is going to happen at 5kHz, which
when using PWM is probably going to be too little. say 256 steps gives
about 20Hz. so what about using SD modulation? i wanted to try this
for a while, maybe now is the time.

yup. works like a charm. since red is less bright, i give it a double
time slot, which leads to a 4 phase state machine.

at receive sample rate there's some noticable flicker at low
intensity, at about 5Hz. it's easy to avoid by introducing a minimum
of 5 or 6 as color values.