从 Raspberry pi 发送串行通信

2022-01-18 00:00:00 python raspberry-pi arduino serial-port

问题描述

我正在使用 Python 程序将串行数据从 Raspberry Pi 发送到 Arduino.我正在运行 Python 2.7.3.程序是:

I am sending serial data from a Raspberry Pi to an Arduino using a Python program. I am running Python 2.7.3. The program is: 

import serial

ser = serial.Serial('/dev/ttyACM0', 115200)

ser.write(b'x4cxffx46')

问题是如果这三行在程序中运行，它们似乎没有发送任何内容.但是，如果我在 Python shell 中逐行运行它们，它们就可以正常工作.

The problem is that nothing seems to be sent by these three lines if they are run in a program. But if I run them line by line in a Python shell, they work fine.

另外，如果我打开了 Arduino 串行监视器，程序也可以正常工作，而无需在 shell 中逐行运行.

Also, if I have the Arduino Serial Monitor open, the program works fine as well, without running the lines one by one in the shell.

编辑添加:

发送到 Arduino 似乎有一些延迟.因此，当我在解释模式下运行代码时，它可以工作，但如果作为程序，它就不行.我认为这是因为我在 Windows 机器上尝试了相同的程序.

It seems that there is some delay in sending to the Arduino. So when I run the code in interpretive mode, it works, but if as a program, it doesn't. I think that because I tried the same program on a Windows machine. 

import serial

ser = serial.Serial('COM8', 115200)

ser.write(b'x4cx20x46')

如果我在解释模式下运行程序，甚至在调试模式下使用 ser.write 命令上的断点，它都可以工作.但如果作为程序运行则不会.

If I run the program in interpretive mode, or even in debugging mode with a breakpoint on the ser.write command, it works. But not if run as a program.

编辑添加更多内容:

事实证明，Arduino 具有必须禁用的串行通信自动重置功能:

It turns out that the Arduino has an auto-reset on serial communications that has to be disabled:

http://playground.arduino.cc/Main/DisablingAutoResetOnSerialConnection#.UwP_wfldV8E

http://forum.arduino.cc/index.php/topic,28723.0.html

我在 RESET 引脚和地之间使用了一个 220 uF 的电容器.这样可行.

I used a 220 uF capacitor between the RESET pin and ground. That works.

很难被这样的虫子咬！它仍然很聪明.

Tough to be bitten by a bug like that! It still smarts.

解决方案

试试这个.如果您无法在空闲等下运行它，请通过键入 python name.py 尝试终端.我还建议您使用 putty 检查来自/写入 Rpi 的数据以确保.

Try this. If you can't run it under idle or etc, try terminal by typing python name.py. I also suggest you to check the data coming or written from/to Rpi with putty to be sure.

import serial
import time


def readlineCR(port):
    rv = ""
    while True:
    ch = port.read()
    rv += ch
    if ch == '' or ch == '':
         return rv


port = serial.Serial("/dev/ttyAMA0", baudrate = 7200, timeout = 2)

while True: 
     rcv = readlineCR(port)
     port.write("I typed: " + repr(rcv))
     print(rcv)

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