challenge2.py

#-*- coding:UTF-8 -*-
import RPi.GPIO as GPIO
import time

#Definition of  motor pin 
IN1 = 20
IN2 = 21
IN3 = 19
IN4 = 26
ENA = 16
ENB = 13

#Set the GPIO port to BCM encoding mode
GPIO.setmode(GPIO.BCM)

#Ignore warning information
GPIO.setwarnings(False)

#Motor pin initialization operation
def motor_init():
    global pwm_ENA
    global pwm_ENB
    global delaytime
    GPIO.setup(ENA,GPIO.OUT,initial=GPIO.HIGH)
    GPIO.setup(IN1,GPIO.OUT,initial=GPIO.LOW)
    GPIO.setup(IN2,GPIO.OUT,initial=GPIO.LOW)
    GPIO.setup(ENB,GPIO.OUT,initial=GPIO.HIGH)
    GPIO.setup(IN3,GPIO.OUT,initial=GPIO.LOW)
    GPIO.setup(IN4,GPIO.OUT,initial=GPIO.LOW)
    #Set the PWM pin and frequency is 2000hz
    pwm_ENA = GPIO.PWM(ENA, 2000)
    pwm_ENB = GPIO.PWM(ENB, 2000)
    pwm_ENA.start(0)
    pwm_ENB.start(0)

#advance
def run(delaytime):
    GPIO.output(IN1, GPIO.HIGH)
    GPIO.output(IN2, GPIO.LOW)
    GPIO.output(IN3, GPIO.HIGH)
    GPIO.output(IN4, GPIO.LOW)
    pwm_ENA.ChangeDutyCycle(30)
    pwm_ENB.ChangeDutyCycle(30)
    time.sleep(delaytime)



#turn left in place
def spin_left(delaytime):
    GPIO.output(IN1, GPIO.LOW)
    GPIO.output(IN2, GPIO.HIGH)
    GPIO.output(IN3, GPIO.HIGH)
    GPIO.output(IN4, GPIO.LOW)
    pwm_ENA.ChangeDutyCycle(50)
    pwm_ENB.ChangeDutyCycle(50)
    time.sleep(delaytime)



#Delay 1s	
time.sleep(1)

try:
    motor_init()
    
    run(1.2) 
    spin_left(0.33)
    run(1.2)  
    spin_left(0.33)
    run(1.2)  
    spin_left(0.33)
    run(1.2)
    

except KeyboardInterrupt:
    pass
pwm_ENA.stop()
pwm_ENB.stop()
GPIO.cleanup()