Serial Control Program
======================


Commands:

l: Set LED outputs. Parameter: Hex byte.
r: Read an address. Parameter: Hex address, one or two bytes.
w: Write an address. Parameter: Hex address, one or two bytes, a '=' and a
   hex byte value.

Examples:

Turn on the first LED:
l01

Read address 0x25 (PORTB on ATmega48):
r25

Write 0x3E to address 0x25 (same as 'l01'):
w25=3E