Encoder

import RPi.GPIO as GPIO
import time

# Set up Raspberry board pin out as BOARD mode
GPIO.setmode(GPIO.BOARD)

#Define input Pin
input_A = 15
input_B = 16

# Set up Rasperry pin Mode
GPIO.setup(input_A, GPIO.IN, pull_up_down = GPIO.PUD.UP)
GPIO.setup(input_B, GPIO.IN, pull_up_down = GPIO.PUD.UP)

# Declare variable
prev_A = True
prev_B = True

print(prev_A)
prev_B
#####################################
def get_encoder_turn():
    # return -1, 0 or +1
    global prev_A, prev_B
    new_A = GPIO.input(input_A)
    new_B = GPIO.input(input_B)
    if new_A != prev_A or new_B != prev_B:
        if prev_A == 0 and new_A == 1:
            result = (prev_B *2 - 1)
        elif prev_B == 0 and new_B == 1:
            result = -(prev_A *2 - 1)
    prev_A, prev_B = new_A, new_B
    time.sleep(0.001)
    return result

counter = 0

while True:
    change = get_encoder_turn()
    if change != 0:
        counter = counter + change
        print(counter)