checkpoint4_2.py

import webiopi
from webiopi.devices.digital import PCF8574A
mcp = PCF8574A(slave=0x38) # 0111000

GPIO = webiopi.GPIO # Assign webiopi library to GPIO object

leds = 4 # number of led outputs in total (negative logic)

for index in range(leds):
  mcp.setFunction(index, GPIO.OUT) #Set pin at index as output
  mcp.digitalWrite(index, GPIO.LOW) # Turn on LED at index for the first time

"""
   Function to toggle logic
"""
def toggleLED(): 
  while True: # Always run loop
    for index in range(leds):
      value = not mcp.digitalRead(index)  # Assign opposite of current state (i.e. high or low) to value 
      mcp.digitalWrite(index, value) # Write assigned value to P[index] output (negative logic)
      if index == 0:
        webiopi.sleep(0.50) # Wait 0.5 seconds
      if index == 1:
        webiopi.sleep(1.0) # Wait 1 second
      if index == 2:
        webiopi.sleep(0.10) # Wait 0.1 seconds
      if index == 3:
        webiopi.sleep(0.20) # Wait 0.2 seconds

toggleLED()