Raspberry Pi uses UART serial port to communicate with serial device

Raspberry Pi hardware version: second generation B+
Raspberry Pi system version

root@raspberrypiroot@raspberrypi:~# lsb_release -a
No LSB modules are available.
Distributor ID:Raspbian
Description:Raspbian GNU/Linux 8.0 (jessie)
Release:8.0
Codename:jessie

Modify the file: vim /boot/cmdline.txt

改成下面这样
root@raspberrypi:~# cat /boot/cmdline.txt
dwc_otg.lpm_enable=0  console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait

 

Reboot the Raspberry Pi:

root@raspberrypi:~# reboot

 

Connect the serial port of Raspberry Pi with other serial devices
Raspberry Pi GND --> GND serial device
Raspberry Pi TXD --> RXD serial device
Raspberry Pi TXD --> RXD serial device

使用pyserial
root@raspberrypi:~# apt-get install python-serial
一个字符内容"return "回显程序，加上"return "
波特率：9600
root@raspberrypi:~# vim python_serial.py
# -*- coding: utf-8 -*  
import serial  
import time  
# 打开串口  
ser = serial.Serial("/dev/ttyAMA0", 9600)  
def main():  
    while True:  
        # 获得接收缓冲区字符  
        count = ser.inWaiting()  
        if count != 0:  
            # 读取内容并回显  
            recv = ser.read(count)+"....return\n\n" 
            ser.write(recv)  
        # 清空接收缓冲区  
        ser.flushInput()  
        # 必要的软件延时  
        time.sleep(0.1)  
      
if __name__ == '__main__':  
    try:  
        main()  
    except KeyboardInterrupt:  
        if ser != None:  
            ser.close() 
运行程序：
root@raspberrypi:~# python python_serial.py

 

test chart