昆仑的山头

#srf04.py coding:utf-8 srf04超声测距模块驱动
import RPi.GPIO as GPIO
import time
from time import ctime, sleep
 
__gproTrig = 16    trig
__gproEcho = 12    echo
#初始化输入、输出gpio口
def init():
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(__gproTrig, GPIO.OUT)
    GPIO.setup(__gproEcho, GPIO.IN)
 
def measure():
    #确保启动前为低电平
    GPIO.output(__gproTrig, False)
    time.sleep(0.0001)
    #启动测距
    GPIO.output(__gproTrig, True)
    time.sleep(0.00001) #10us
    GPIO.output(__gproTrig, False)
    #开始记时
    start   = 0
    stop    = 0
   #         print("measure--1")
    while start == 0 or stop == 0:
        val     = GPIO.input(__gproEcho)
        if stop == 0 and start == 0 and val == 1:
   #         print("measure--2")
            start = time.time()
        if start > 0 and stop == 0 and val == 0:
      #      print("measure--3")
            stop = time.time()
    #根据驱动公式计算测距结果
    elapsed = stop - start
    distance = (elapsed * 34300)/2
    return distance
 
if __name__ == '__main__':
    init()
    for i in range(300)://五分钟测试
     #   print("srf05-start:", i)
        dis = measure()
        print('--------------dis:', dis)
        sleep(1)