import sys, time

from machine import Pin, UART



led = Pin("LED", Pin.OUT)
gp = [Pin(i, Pin.OUT) for i in range(8)]

time.sleep(0.1) # Wait for USB to become ready

print("GPIO expander")

state = 0
while True:
  buf = sys.stdin.readline()
  cmd, _, num = buf.partition(' ')
  if buf.startswith("set"):
    state = int(num)
  else:
    continue

  for i in range(8):
    # Invert the logic (open-drain means 0s are "on"), but 
    # it's easier if 1s are "on"
    gp[i].value(((state>>i) & 1) ^ 1)
  sys.stdout.write('State: {:x}\n'.format(state))