I have made up a circuit with a picaxe 08. It has pins 0,1,2 and 4 as outputs to LEDs. It has pin 3 as a serial and trigger input. It is loaded with the following program:
symbol unitid = 1
let dirs = %00010111
if pin3 = 1 then
serin 3,N2400,(24,"p",unitid)
pins = %00010111
serin...