import RPi.GPIO as GPIO
import time
from smbus import SMBus
bus = SMBus(1)

an0 = 0
leda = 20
in5 = 5
led_pow = 22

GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)
GPIO.setup(leda,GPIO.OUT)
GPIO.setup(led_pow,GPIO.OUT)
GPIO.setup(in5,GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.output(leda,GPIO.LOW)


def read_ain(i):    
    global bus
    bus.write_byte(0x48, i)
    bus.read_byte(0x48)
    return bus.read_byte(0x48)

print "CTRL+C = STOP program"

try:
    while True:
        an0 = read_ain(0)
        print "an0= "+str(an0)
        val = 160 - an0 # PULL UP on 3.3V
        ledv = val + 70 # > 150 turn LED ON  (50%)
        bus.write_byte_data(0x48, 0x40, ledv) # analog LED
        
        if an0 < 146: # value depends on termistor (4.7K)
            GPIO.output(leda,GPIO.HIGH)
        else:
            GPIO.output(leda,GPIO.LOW)
            
        if GPIO.input(in5) == 0:
            GPIO.output(led_pow,GPIO.HIGH)
        else:
            GPIO.output(led_pow,GPIO.LOW)          
except KeyboardInterrupt:
    GPIO.cleanup()  # must be executed before program stop