Single Ultrasonic Sensor Motor Control Using ROS

#!/usr/bin/env python
import RPi.GPIO as GPIO
from time import sleep

import rospy
from std_msgs.msg import Float32

GPIO.setmode(GPIO.BOARD)
 
Motor1A = 16
Motor1B = 18
Motor1E = 22

Motor2A = 23
Motor2B = 21
Motor2E = 19


GPIO.setup(Motor1A,GPIO.OUT)
GPIO.setup(Motor1B,GPIO.OUT)
GPIO.setup(Motor1E,GPIO.OUT)

GPIO.setup(Motor2A,GPIO.OUT)
GPIO.setup(Motor2B,GPIO.OUT)
GPIO.setup(Motor2E,GPIO.OUT)

def callback(data):
    rospy.loginfo( "I heard %s", data.data)
    if data.data>=20 :
        GPIO.output(Motor1A,GPIO.HIGH)
        GPIO.output(Motor1B,GPIO.LOW)
        GPIO.output(Motor1E,GPIO.HIGH)
 
        GPIO.output(Motor2A,GPIO.HIGH)
        GPIO.output(Motor2B,GPIO.LOW)
        GPIO.output(Motor2E,GPIO.HIGH)

    else:
        GPIO.output(Motor1A,GPIO.LOW)
        GPIO.output(Motor1B,GPIO.HIGH)
        GPIO.output(Motor1E,GPIO.HIGH)
 
        GPIO.output(Motor2A,GPIO.LOW)
        GPIO.output(Motor2B,GPIO.HIGH)
        GPIO.output(Motor2E,GPIO.HIGH)
 
        sleep(2)
        GPIO.output(Motor1A,GPIO.HIGH)
        GPIO.output(Motor1B,GPIO.LOW)
        GPIO.output(Motor1E,GPIO.HIGH)

        GPIO.output(Motor2A,GPIO.LOW)
        GPIO.output(Motor2B,GPIO.HIGH)
        GPIO.output(Motor2E,GPIO.HIGH)
    
    
    
def listener():

    
    rospy.init_node('motor_driver', anonymous=True)

    rospy.Subscriber("distance", Float32, callback)

    # spin() simply keeps python from exiting until this node is stopped
    rospy.spin()

if __name__ == '__main__':
    listener()