树莓派小车——红外避障模块

红外线对白色反射强烈；阳光下会有干扰！！！

原理：

白色为发射管，黑色为接收管，3个针脚，一个输入输出引脚；有障碍物低电平2亮灯;没有障碍物，一个灯亮（小蓝色的方块调节灵敏度）

发射管一直在发射红外光，当前面的障碍物越近，反射回来的红外光越强，红外接收管的EC电压越接近0V，那么就会小于LM393的2脚的电压，LM393输出低电平，绿色指示灯亮。

　　在实际使用中红外接收管工作在放大区，也就是说C点的电压在不断的变化。所以我们调节LM393的2脚的电压来改变灵敏度。

代码：

#!/usr/bin/python  
# coding=utf-8  
#本段代码实现树莓派智能小车的红外避障效果
#代码使用的树莓派GPIO是用的BOARD编码方式。 
import RPi.GPIO as GPIO  
import time  
import sys 
 
SensorRight = 16    #右边的红外避障模块接口
SensorLeft  = 12    #左边的红外避障接口

PWMA   = 18
AIN1   = 22
AIN2   = 27

PWMB   = 23
BIN1   = 25
BIN2   = 24

BtnPin  = 19
Gpin    = 5
Rpin    = 6
#基本运动函数
def t_up(speed,t_time):
        L_Motor.ChangeDutyCycle(speed)
        GPIO.output(AIN2,False)#AIN2
        GPIO.output(AIN1,True) #AIN1

        R_Motor.ChangeDutyCycle(speed)
        GPIO.output(BIN2,False)#BIN2
        GPIO.output(BIN1,True) #BIN1
        time.sleep(t_time)
        
def t_stop(t_time):
        L_Motor.ChangeDutyCycle(0)
        GPIO.output(AIN2,False)#AIN2
        GPIO.output(AIN1,False) #AIN1

        R_Motor.ChangeDutyCycle(0)
        GPIO.output(BIN2,False)#BIN2
        GPIO.output(BIN1,False) #BIN1
        time.sleep(t_time)
        
def t_down(speed,t_time):
        L_Motor.ChangeDutyCycle(speed)
        GPIO.output(AIN2,True)#AIN2
        GPIO.output(AIN1,False) #AIN1

        R_Motor.ChangeDutyCycle(speed)
        GPIO.output(BIN2,True)#BIN2
        GPIO.output(BIN1,False) #BIN1
        time.sleep(t_time)

def t_left(speed,t_time):
        L_Motor.ChangeDutyCycle(speed)
        GPIO.output(AIN2,True)#AIN2
        GPIO.output(AIN1,False) #AIN1

        R_Motor.ChangeDutyCycle(speed)
        GPIO.output(BIN2,False)#BIN2
        GPIO.output(BIN1,True) #BIN1
        time.sleep(t_time)

def t_right(speed,t_time):
        L_Motor.ChangeDutyCycle(speed)
        GPIO.output(AIN2,False)#AIN2
        GPIO.output(AIN1,True) #AIN1

        R_Motor.ChangeDutyCycle(speed)
        GPIO.output(BIN2,True)#BIN2
        GPIO.output(BIN1,False) #BIN1
        time.sleep(t_time)
        
def keysacn():#？？？？？按钮？？
    val = GPIO.input(BtnPin)
    while GPIO.input(BtnPin) == False:
        val = GPIO.input(BtnPin)
    while GPIO.input(BtnPin) == True:
        time.sleep(0.01)
        val = GPIO.input(BtnPin)
        if val == True:
            GPIO.output(Rpin,1)
            while GPIO.input(BtnPin) == False:
                GPIO.output(Rpin,0)
        else:
            GPIO.output(Rpin,0)
            
def setup():#设置输出输入接口
    GPIO.setwarnings(False)
    GPIO.setmode(GPIO.BCM)       # Numbers GPIOs by physical location
    GPIO.setup(Gpin, GPIO.OUT)     # Set Green Led Pin mode to output
    GPIO.setup(Rpin, GPIO.OUT)     # Set Red Led Pin mode to output
    GPIO.setup(BtnPin, GPIO.IN, pull_up_down=GPIO.PUD_UP)    # Set BtnPin's mode is input, and pull up to high level(3.3V) 
    GPIO.setup(SensorRight,GPIO.IN)
    GPIO.setup(SensorLeft,GPIO.IN)
	
    GPIO.setup(AIN2,GPIO.OUT)
    GPIO.setup(AIN1,GPIO.OUT)
    GPIO.setup(PWMA,GPIO.OUT)

    GPIO.setup(BIN1,GPIO.OUT)
    GPIO.setup(BIN2,GPIO.OUT)
    GPIO.setup(PWMB,GPIO.OUT)
    
if __name__ == '__main__':
    setup()
    keysacn()
    L_Motor= GPIO.PWM(PWMA,100)#左右使能
    L_Motor.start(0)
    R_Motor = GPIO.PWM(PWMB,100)
    R_Motor.start(0)
    try:
        while True:
            #SR_2和SL_2分别读取左右两边----红外避障模块的状态；低电平有障碍物
            SR_2 = GPIO.input(SensorRight)#高低电平判断！
            SL_2 = GPIO.input(SensorLeft)
            if SL_2 == True and SR_2 == True:#当碰到障碍物时候——红外模块输入低电平
                print("t_up")
                t_up(50,0)
            elif SL_2 == True and SR_2 ==False:#右边有障碍物向左
                print("Left")
                t_left(50,0)
            elif SL_2==False and SR_2 ==True:
                print("Right")
                t_right(50,0)
            else:#左右两边都有障碍物！
                t_stop(0.3)
                t_down(50,0.4)
                t_left(50,0.5)
    except KeyboardInterrupt:  # When 'Ctrl+C' is pressed, the child program destroy() will be  executed.
        GPIO.cleanup()