python - 使用 python 通过 BBB 读取多个超声波传感器

Question

所以我开始使用 hc-sr04 超声波传感器并遇到了问题。我想读取多个传感器(初学者有两个)，但两个传感器上的距离值相同。这是代码:

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import Adafruit_BBIO.GPIO as GPIO
import time

def distanceMeasurement(TRIG,ECHO):

    GPIO.output(TRIG, True)
    time.sleep(0.00001)
    GPIO.output(TRIG, False)

    while GPIO.input(ECHO) == 0:
        pulseStart = time.time()
    while GPIO.input(ECHO) == 1:
        pulseEnd = time.time()

    pulseDuration = pulseEnd - pulseStart
    distance = pulseDuration * 17150
    distance = round(distance, 2)
    return distance

#Configuration
GPIO.setup("P9_15",GPIO.OUT) #Trigger
GPIO.setup("P9_12",GPIO.IN)  #Echo
GPIO.setup("P9_11",GPIO.OUT)
GPIO.setup("P9_13",GPIO.IN)

#Security
GPIO.output("P9_11", False)
GPIO.output("P9_15", False)
time.sleep(0.5)

#main Loop
try:
    while True:
       for i in range(2):
           if i == 0:
               recoveredDistance = distanceMeasurement("P9_11","P9_13")
               print "Distance1: ",recoveredDistance,"cm"
           elif i == 1:
               recoveredDIstance = distanceMeasurement("P9_15","P9_12")
               print "Distance2: ",recoveredDistance,"cm"
       time.sleep(1)
except KeyboardInterrupt:
    print "Measurement stopped by user"
    GPIO.cleanup()

无论传感器 2 上到物体的距离如何，我都得到相同的读数，传感器 1 中读取的距离就是两者显示的距离；似乎sensor2被忽略了。

进行一些“手动调试”(即打印 TRIG、ECHO)，我注意到该函数接收了正确的参数，这是“调试”的输出:

P9_11
P9_13

Distance1:  20.79 cm
P9_15
P9_12

Distance2:  20.79 cm
P9_11
P9_13

Distance1:  20.13 cm
P9_15
P9_12

我想使用这一功能来读取所有传感器。预先感谢您

Answer 1

您将相同的结果打印两次，因为第二次测量被保存为 recoveredDIstance。所以 recoveredDistance 没有改变。 Python 区分大小写。

while True:
    recoveredDistance = distanceMeasurement("P9_11","P9_13")
    print "Distance1: ", recoveredDistance, "cm"
    recoveredDistance = distanceMeasurement("P9_15","P9_12")
    print "Distance2: ", recoveredDistance, "cm"
    time.sleep(1)