Ubuntu analog serial communication

Ubuntu serial communication###

#1 surroundings##

Ubuntu 16.04(Mac virtual machine)
Python 3.5

#1.1 Install plugin###

  1. Ubuntu serial port assistant
sudo apt install cutecom

  1. Python third-party library
pip3 install pyserial

#2 purpose##

#3 Start##

#3.1 Virtual serial port###

Why virtual serial port???

Because there is no serial port device on my computer, I need to virtualize the serial port to perform serial communication. This is very, very important!!!, if there is no serial port peripheral on the computer, and there is no virtual available serial port, it cannot be done Serial communication!

#! /usr/bin/env python
# coding=utf-8import pty
import os
import select

def mkpty():
 master1, slave = pty.openpty()
 slaveName1 = os.ttyname(slave)
 master2, slave = pty.openpty()
 slaveName2 = os.ttyname(slave)print('\nslave device names: ', slaveName1, slaveName2)return master1, master2

if __name__ =="__main__":

 master1, master2 =mkpty()print(master1, master2)while True:
  rl, wl, el = select.select([master1,master2],[],[],1)for master in rl:print(master)
   data = os.read(master,128)if master==master1:
    os.write(master2, data)else:
    os.write(master1, data)

slave device names:/dev/pts/18/dev/pts/20

Among them, /dev/pts/18 and /dev/pts/20 are serial devices virtually transmitted on Ubuntu

Verify that the virtual serial port is available:

  1. Open cutecom
sudo cutecom

  1. use

The virtual serial port can be used normally!

#3.2 Receive serial port data###

Receive code:

# usr/bin/python3
# - *- coding: utf-8-*-import serial
ser=serial.Serial("/dev/pts/18",115200,timeout=0.5)print("serial_name:",ser.name)
ser.close()
ser.open()print(ser.isOpen())while True:

 s = ser.read(10) #Read every 10 characters
 # s = ser.readline() #Is to read a line to/n end, if not/n keep reading, blocking.

 print(s)

ser.close()#Close port

serial API:

serial method Description Remarks
serial.Serial Instantiate a serial port object ser=serial.Serial("/dev/pts/18",115200,timeout=0.5)
ser.name Serial port name
ser.open() Open the serial port (if opening fails, close it before opening)
ser.close() Close the serial port
ser.read(x) is to read x characters
ser.readline() Read a line and end with /n. If there is no /n, keep reading and block.
ser.readlines() Read multiple lines, you need to set the timeout time
ser.xreadlines() Read multiple lines, need to set timeout time
ser.write("x") write data
ser.baudrate Baud rate
ser.bytesize byte size
ser.parity Check Digit
ser.stopbits stop bits
ser.timeout Read timeout setting
ser.writeTimeout write timeout
ser.xonxoff Software Flow Control
ser.rtscts Hardware Flow Control
ser.interCharTimeout Character interval timeout

#3.3 Write serial port data###

write the code:

# usr/bin/python3
# - *- coding: utf-8-*-import serial
ser=serial.Serial("/dev/pts/18",115200,timeout=0.5)print("serial_name:",ser.name)
ser.close()
ser.open()print(ser.isOpen())

# while True:

ser.write(b"hello") #Binary

ser.close()#Close port

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Ubuntu analog serial communication