Aqui hay uno código de la revista ucontrol
clock var PORTb.0
dat var PORTb.1
reset var portb.2
coluna var Byte
TRISB = %00000000
main:
For coluna = 1 To 8
If dato.7 = 0 Then
dat = 0
clock = 0
pause 1
clock = 1
pause 1
Else
dat = 1
clock = 0
pause 1
clock = 1
pause 1
Endif
aux = dato + 1
Next coluna
goto main