Sample code for most PIC18F4520 operations

These will/should also have wiki pages for background and associated electronics:

Digital input and output bit-by-bit or byte-by-byte

Reading up to twelve Analog Inputs

Counting pulses with Timer0

Counting pulses with Timer1

PWM outputs for torque control of one or two DC motors; Timer 2

Serial RS232 communication between PIC and a text window

Periodic servo cycles using interrupt routines, 10mS & slower; Timer 0

Periodic servo cycles using interrupt routines; 10mS & faster; Timer 2

Interrupts generated by an external pulse

PWM output in software for position control of up to five RC servos; Timer 3

PWM output in hardware for position control of up to two RC servos; Timer 2

Quadrature decoder/counter in software for arbitarily many encoders; 1KHz max

Quadrature decoder/counter in hardware for one fast encoder; Timers 0 and 1

Not available yet:

Analog output using 8 digital lines

Analog output using I2C serial

Printing to a serial LCD

Printing to a parallel LCD

PIC-to-PIC communication

Zigbee radio communication

Modulated IR communication

Strobing LEDs or IREDs for better range and immunity to background light

I2C communication

CAN bus

Capturing data to Matlab

Running stepper motors