SOURCE CODE

 import serial

import RPi.GPIO as GPIO

M1=13

M2=6

M3=7

M4=12

GPIO.setmode(GPIO.BCM)

GPIO.setup(M1,GPIO.OUT)

GPIO.setup(M2,GPIO.OUT)

GPIO.setup(M3,GPIO.OUT)

GPIO.setup(M4,GPIO.OUT)

port = serial.Serial("/dev/ttyAMA0", baudrate=9600, timeout=1)

data1=" "

data=" "

def left(): #left

    print("forward")

    

    GPIO.output(M1, True)    

    GPIO.output(M2, False)

    GPIO.output(M3, True)

    GPIO.output(M4, False)

    

def right():

    print('backward')

    

    GPIO.output(M1, False)

    GPIO.output(M2, True)

    GPIO.output(M3, False)

    GPIO.output(M4, True)

def backward():

    print('right')

    

    GPIO.output(M1, False)

    GPIO.output(M2, True)

    GPIO.output(M3, True)

    GPIO.output(M4, False)

def forward():

    print('left')

    

    GPIO.output(M1, True)

    GPIO.output(M2, False)

    GPIO.output(M3, False)

    GPIO.output(M4, True)

def stop():

    print('stop')

    

    GPIO.output(M1, True)

    GPIO.output(M2, True)

    GPIO.output(M3, False)

    GPIO.output(M4, False)

    

stop()

while 1:

 data = str(port.read(1))

 data1+=data

 a=data1[3]

 #print (data1)

 if 'U' in data1:

     forward()

 if 'D'in data1:

     backward()

 if 'R' in data1:

     right()

 if 'L' in data1:

     left()

 if 'C' in data1:

     stop()

     

 print(data1[3]) 

 port.flush()

 data=" "

 data1=" "