Question

我尝试通过USB线将Arduino连接到树莓派。 Arduino板连接到超声波传感器，并根据是否在一定距离内找到障碍物（非常简单的代码）发送0或1的串行消息。问题是这样的：我正在尝试让Raspberry Pi读取Arduino代码并同时播放mp3文件，但由于某些原因似乎不起作用！我不确定问题是否在于编码或者如果Pi可能无法响应从Arduino发送到串行监视器的消息（如果是这样的话会非常难过）。任何帮助将非常感激

这是Arduino代码（我正在使用UNO板）：

    /*
HC-SR04 Ping distance sensor:

VCC to Arduino

Vin GND to Arduino GND

Echo to Arduino pin 12

Trig to Arduino pin 11 */

#include <NewPing.h> //downloaded from the internet & unzipped in libraries folder in Arduino Directory

#define TRIGGER_PIN 11 // Arduino pin tied to trigger pin on the ultrasonic sensor.

#define ECHO_PIN 12 // Arduino pin tied to echo pin on the ultrasonic sensor.

int maximumRange = 70; // Maximum range needed

int minimumRange = 35; // Minimum range needed

long duration, distance; // Duration used to calculate distance

void setup() {

Serial.begin (9600);

pinMode(TRIGGER_PIN, OUTPUT);

pinMode(ECHO_PIN, INPUT);

}

void loop() {

/* The following trigPin/echoPin cycle is used to determine the distance of the nearest object through reflecting soundwaves off of it */

digitalWrite(TRIGGER_PIN, LOW);

delayMicroseconds(2);

digitalWrite(TRIGGER_PIN, HIGH);

delayMicroseconds(10);

digitalWrite(TRIGGER_PIN, LOW);

duration = pulseIn(ECHO_PIN, HIGH);

distance = (duration/2) / 29.1; //formula to convert the value measured by the ultrasonic sensor into centimeters

if (distance >= maximumRange || distance <= minimumRange)

{

Serial.println("0"); //means the path is clear

}

else {

Serial.println("1"); //means there is an obstacle in front of the ultrasonic sensor !

}

delay(50); //Delay 50ms before next reading.

}

这是我在Pi中使用的python代码（我有Raspberry Pi 2）：注意：由于我尝试了下面显示的许多不同的代码组合，我已经评论了不起作用的部分

import serial
import RPi.GPIO as GPIO
import sys
import os
from subprocess import Popen
from subprocess import call
import time
import multiprocessing

GPIO.setmode(GPIO.BOARD)
GPIO.setwarnings(False)

arduinoSerialData = serial.Serial('/dev/ttyACM0', 9600)

while True:



time.sleep(0.01)
if(arduinoSerialData.inWaiting()>0):
myData = arduinoSerialData.readline()
print(myData)

if myData == '1': #THIS IS WHERE THE PROBLEMS START
#os.system('omxplayer sound.mp3') #tried this didn't work
#os.system('python player.py') #which is basically a python program with the previous line in it, also not working!
# I even tried enclosing that part (after if myData == '1') in a while loop and also didn't work !

Answer 1

首先，您的IF条件看起来不正确。我不知道distance <= minimumRange如何表明路径是清楚的。

接下来，您正在向串口写入一行;一行可以是0\r\n或1\r\n。然后你正在阅读Arduino中的一行，返回上述两种可能性中的一种。然后，您将已阅读的行与1进行比较。 0\r\n和1\r\n都不等于1，因此条件永远不会出错也就不足为奇了。您可以通过多种方式解决此问题：

将Serial.println()更改为Serial.print()
将arduinoSerialData.readline()更改为arduinoSerialData.readline().rstrip()
将条件更改为if 1 in myData:

要记住的另一件事是，read()在Python 3中返回一个bytes对象而不是在Python 2中返回一个字符串。因此，任何涉及文字的比较都应确保包含必需的b''信封。例如，如果从读取数据中删除CRLF，则您的条件应为if myData == b'1':。

如何让Raspberry pi通过USB连接响应Arduino代码

1 个答案: