python的串口通信(pyserial)

1 使用用硬件

树莓派，CH340串口转USB两个，PC

2 环境安装

树莓派我使用的是自带系统，环境都已经配好了，PC这边我安装了的ubunt子系统，有python环境，那么就需要安装pyserial库和CH340的驱动

sudo apt-get update
sudo apt install python-pip
pip install --upgrade pip
pip install pyserial

可以使用命令查看本机的串口

python -m serial.tools.list_ports
python3 -m serial.tools.list_ports

PC的话将会列举一堆，需要取设备管理器中找到对应的COM口号，例如我串口是COM8，则是用的/dev/ttyS5
树莓派的话将会显示两个，/dev/ttyAMA0是GPIO处的串口，/dev/ttyUSB0则是我插入的串口转USB模块

pi@raspberrypi:~ $ python -m serial.tools.list_ports
/dev/ttyAMA0
/dev/ttyUSB0

3 收发测试

lissettecarlr@lissettecarlr ~ % python
Python 2.7.12 (default, Nov 12 2018, 14:36:49)
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import serial
>>> com=serial.Serial('/dev/ttyS8',115200,timeout=0.2)
>>> com.isOpen()
True
>>> com.write('123')
3
>>> com.readline()
'lalala'
>>>

树莓派

root@raspberrypi:~# python
Python 2.7.13 (default, Sep 26 2018, 18:42:22)
[GCC 6.3.0 20170516] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import serial
>>> com=serial.Serial('/dev/ttyUSB0',115200,timeout=0.5)
>>> com.isOpen()
True
>>> com.readline()
'123'
>>> com.write('lalala')
6
>>>

4 miniterm

这是一个简单的串口收发工具，在控制台每输入一个字符将被立即发送出去。而接收到的信息会被打印在当前窗口中
例如

pi@raspberrypi:~ $ python -m serial.tools.list_ports
/dev/ttyAMA0
/dev/ttyUSB0
2 ports found
pi@raspberrypi:~ $ sudo miniterm.py /dev/ttyUSB0
--- Miniterm on /dev/ttyUSB0  9600,8,N,1 ---
--- Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---
AT

image.png

5编写一个串口收发的小程序

该程序接收控制台输入，将其串口发送出去，如若需要接收对应模组应答信息，则将屏蔽取消

import serial
import os
import threading
import serial.tools.list_ports
from time import sleep

def rcv_data():
    while True:
        rcv=serial.readline()
        rcv=rcv.decode() 
        print(rcv)

if __name__=='__main__':
    port_list = list(serial.tools.list_ports.comports())
    k=0
    for i in port_list:
        print(i,k)
        k=k+1

    if len(port_list) <= 0:
        print("not find serial")
    else:
        serial_k=input("please switch serial:")
        k = int(serial_k)
        serial_list = list(port_list[k])
        serialName = serial_list[0]
        #print(serialName)
        serial=serial.Serial(serialName,115200,timeout=3600)
        th=threading.Thread(target=rcv_data)
        th.setDaemon(True)
        th.start()
        if serial.isOpen():
            print("open succeed >",serial.name)
        else:
            print("open failed >",serial.name)
        while True:
            send_data=input("=>")
            send_data = send_data + '\r\n'
            serial.write(send_data.encode())
        #  data=serial.read(1)
        #  sleep(0.1)
        #  data = (data + serial.read(serial.inWaiting())).decode()
        #  print(data)

运行结果