树莓派使用红外感应传感器

一个简单的被动红外传感器可以让你检测运动状态。这个传感器有三个引脚，可用于连接到Raspberry Pi的GPIO端。当模块检测到运动状态时，其中一个引脚会输出高压，输出电压约为3.3V。如果连续检测到运动状态，引脚的电压将保持在水平，直到无法检测到运动状态。另外两个引脚分别是5V和GND，连接后的代码如下：

import RPi.GPIO as GPIO

import time

# Use BCM GPIO references

# instead of physical pin numbers

GPIO.setmode(GPIO.BCM)

# Define GPIO to use on Pi

GPIO_PIR = 7

print "PIR Module Test (CTRL-C to exit)"

# Set pin as input

GPIO.setup(GPIO_PIR,GPIO.IN) # Echo

Current_State = 0

Previous_State = 0

try:

print "Waiting for PIR to settle ..."

# Loop until PIR output is 0

while GPIO.input(GPIO_PIR)==1:

Current_State = 0

print " Ready"

# Loop until users quits with CTRL-C

while True :

# Read PIR state

Current_State = GPIO.input(GPIO_PIR)

if Current_State==1 and Previous_State==0:

# PIR is triggered

print " Motion detected!"

# Record previous state

Previous_State=1

elif Current_State==0 and Previous_State==1:

# PIR has returned to ready state

print " Ready"

Previous_State=0

# Wait for 10 milliseconds

time.sleep(0.01)

except KeyboardInterrupt:

print " Quit"

# Reset GPIO settings

GPIO.cleanup()