import RPi.GPIO as GPIO
import time
from smbus import SMBus
bus = SMBus(1)
an0 = 0
led1 = 23
led2 = 22
led3 = 25

color_pw = 20
br1 = 0
br2 = 0
br3 = 0

GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)
GPIO.setup(led1,GPIO.OUT)
GPIO.setup(led2,GPIO.OUT)
GPIO.setup(led3,GPIO.OUT)
GPIO.setup(color_pw,GPIO.OUT)

GPIO.output(led1,GPIO.LOW)
GPIO.output(led2,GPIO.LOW)
GPIO.output(led3,GPIO.LOW)
GPIO.output(color_pw,GPIO.HIGH)

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(1)
        val = 160 - an0 # PULL UP on 3.3V
        ledv = val + 70 # > 150 turn LED ON  (50%)       
        print str(an0)
        print "-"
        bus.write_byte_data(0x48, 0x40, ledv) # analog LED     
        if an0 > 156 and br1 > 3:
            GPIO.output(led1,GPIO.HIGH)
            br1 = 0
        else:
            GPIO.output(led1,GPIO.LOW)
        if an0 < 153 and br2 > 3:
            GPIO.output(led2,GPIO.HIGH)
            br2 = 0
        else:
            GPIO.output(led2,GPIO.LOW)
        if an0 == 156 and br3 > 3:
            GPIO.output(led3,GPIO.HIGH)
            br3 = 0
        else:
            GPIO.output(led3,GPIO.LOW)

        # samples for better precision    
        if an0 == 156 or an0 == 155:
            br3 = br3 + 1
        if an0 < 153:
            br2 = br2 + 1
        if an0 > 156:
            br1 = br1 + 1
            
except KeyboardInterrupt:
    GPIO.cleanup()  # must be executed before program stop