import RPi.GPIO as GPIO
import time

mota = 22
motb = 23

sig = 27
ele_pow = 20
stp = 0
ids = 0

GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)
GPIO.setup(mota,GPIO.OUT)
GPIO.setup(motb,GPIO.OUT)
GPIO.setup(sig,GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(ele_pow,GPIO.OUT)

GPIO.output(ele_pow,GPIO.HIGH)

p2 = GPIO.PWM(motb, 50) # GPIO PWM with 50Hz

num_steps = 148
print "CTRL+C = STOP program"
p2.start(0)

try:
    while True:
        n = 20 # speed
        p2.ChangeDutyCycle(n)         
        while stp < num_steps:         
            if GPIO.input(sig) == 1 and ids == 0:
                stp = stp + 1
                ids = 1
                print(stp)                 
            if GPIO.input(sig) == 0 and ids == 1:
                stp = stp + 1             
                ids = 0             
                print(stp) 
        p2.ChangeDutyCycle(0)
        time.sleep(2)
        stp = 0
except KeyboardInterrupt:
    GPIO.cleanup()  # must be executed before program stop