【Python】基于serial的UART串口通信（可实现AT指令自动化 以ML307A开发板为例）
Python下的串口serial库
串行口的属性：
name:设备名字
portstr:已废弃，用name代替
port：读或者写端口
baudrate：波特率
bytesize：字节大小
parity：校验位
stopbits：停止位
timeout：读超时设置
writeTimeout：写超时
xonxoff：软件流控
rtscts：硬件流控
dsrdtr：硬件流控
interCharTimeout:字符间隔超时
属性的使用方法：
ser=serial.Serial(“/dev/ttyAMA0”,9600,timeout=0.5)
ser.open()
print ser.name
print ser.port
print ser.baudrate#波特率
print ser.bytesize#字节大小
print ser.parity#校验位N－无校验，E－偶校验，O－奇校验
print ser.stopbits#停止位
print ser.timeout#读超时设置
print ser.writeTimeout#写超时
print ser.xonxoff#软件流控
print ser.rtscts#硬件流控
print ser.dsrdtr#硬件流控
print ser.interCharTimeout#字符间隔超时
ser.close()
串口接收要用到多线程库（类似单片机中的中断）：
def thread_com_receive():
global ML307A_RX
while True:
try:
rx_buf = ''
rx_buf = COMM.read() # 转化为整型数字
if rx_buf != b'':
time.sleep(0.01)
rx_buf = rx_buf + COMM.read_all()
print("串口收到消息:", rx_buf)
ML307A_RX=str(rx_buf).split("\\r\\n")[1]
print(ML307A_RX)
time.sleep(0.01)
except:
pass
pass
初始化串口：
# 打开串口
def serial_open(n=0):
global COMM
serial_port = set_com_port(n)
COMM = serial.Serial(serial_port, 115200, timeout=0.01)
if COMM.isOpen():
print(serial_port, "open success")
return 0
else:
print("open failed")
return 255
def init_com():
global ML307A_RX
get_com_list()
len = port_list.__len__()
device = port_list[0].device
print(len, device)
serial_open()
thread1 = threading.Thread(target=thread_com_receive)
thread1.start()
COMM.write("AT\r\n".encode("UTF-8"))
time.sleep(0.1)
if ML307A_RX=="OK":
com_jugg()
AT的命令格式
AT指令格式：AT指令都以”AT”开头,以0x0D 0x0A(即\r\n,换行回车符)结束，模块运行后,串口默认的设置为：8位数据位、1位停止位、无奇偶校验位、硬件流控制（CTS/RTS）.
注意为了发送AT命令,最后还要加上0x0D 0x0A(即\r\n,换行回车符)这是串口终端要求.
有一些命令后面可以加额外信息来.如电话号码
每个AT命令执行后,通常DCE都给状态值,用于判断命令执行的结果.
AT返回状态包括三种情况 OK,ERROR,和命令相关的错误原因字符串.返回状态前后都有一个字符.
如 OK 表示AT命令执行成功.
ERROR 表示AT命令执行失败
NO DIAL TONE 只出现在ATD命令返回状态中,表示没有拨号音,这类返回状态要查命令手册
还有一些命令本身是要向DCE查询数据,数据返回时,一般是+打头命令.返回格式
+命令:命令结果
如:AT+CMGR=8 (获取第8条信息)
返回 +CMGR: “REC UNREAD”,“+8613508485560”,“01/07/16,15:37:28+32”,Once more
AT指令串口通信代码如下：
# -*- coding: utf-8 -*-
import serial
import serial.tools.list_ports
import time
import threading
com_rx_buf = '' # 接收缓冲区
com_tx_buf = '' # 发送缓冲区
COMM = serial.Serial() # 定义串口对象
port_list: list # 可用串口列表
port_select: list # 选择好的串口
ML307A_RX=''
# 无串口返回0，
# 返回可用的串口列表
def get_com_list():
global port_list
# a = serial.tools.list_ports.comports()
# print(a)
# port_list = list(serial.tools.list_ports.comports())
port_list = serial.tools.list_ports.comports()
return port_list
def set_com_port(n=0):
global port_list
global port_select
port_select = port_list[n]
return port_select.device
# 打开串口
def serial_open(n=0):
global COMM
serial_port = set_com_port(n)
COMM = serial.Serial(serial_port, 115200, timeout=0.01)
if COMM.isOpen():
print(serial_port, "open success")
return 0
else:
print("open failed")
return 255
# 关闭串口
def serial_close():
global COMM
COMM.close()
print(COMM.name + "closed.")
def set_com_rx_buf(buf=''):
global com_rx_buf
com_rx_buf = buf
def set_com_tx_buf(buf=''):
global com_tx_buf
com_tx_buf = buf
def get_com_rx_buf():
global com_rx_buf
return com_rx_buf
def get_com_tx_buf():
global com_tx_buf
return com_tx_buf
def thread_com_receive():
global ML307A_RX
while True:
try:
rx_buf = ''
rx_buf = COMM.read() # 转化为整型数字
if rx_buf != b'':
time.sleep(0.01)
rx_buf = rx_buf + COMM.read_all()
print("串口收到消息:", rx_buf)
ML307A_RX=str(rx_buf).split("\\r\\n")[1]
print(ML307A_RX)
time.sleep(0.01)
except:
pass
pass
# def serial_encode(addr=0, command=0, param1=0, param0=0):
# buf = [addr, command, param1, param0, 0, 0, 0, 0]
# print(buf)
# return buf
def serial_send_command(addr=0, command=0, param1=0, param0=0, data3=0, data2=0, data1=0, data0=0):
buf = [addr, command, param1, param0, data3, data2, data1, data0]
COMM.write(buf)
pass
def serial_init():
buf = "AT+CG\r\n"
COMM.write(buf)
time.sleep(0.05)
buf = COMM.read_all()
if buf != "OK\r\n":
return 254 # 进入调试模式失败
buf = "AT+CAN_MODE=0\r\n"
COMM.write(buf)
time.sleep(0.05)
buf = COMM.read_all()
if buf != "OK\r\n":
return 253 # 进入正常模式失败，模块处于1状态，即环回模式中
buf = "AT+CAN_BAUD=500000\r\n"
COMM.write(buf)
time.sleep(0.05)
buf = COMM.read_all()
if buf != "OK\r\n":
return 253 # 波特率设置失败
buf = "AT+FRAMEFORMAT=1,0,\r\n"
COMM.write(buf)
time.sleep(0.05)
buf = COMM.read_all()
if buf != "OK\r\n":
return 253 # 波特率设置失败
buf = "AT+ET\r\n" # 进入透传模式
COMM.write(buf)
time.sleep(0.05)
buf = COMM.read_all()
if buf != "OK\r\n":
return 255 # 不是CAN模块
def com_jugg():
global ML307A_RX
while True:
COMM.write("""AT+MUESTATS="radio"\r\n""".encode("UTF-8"))
time.sleep(5)
print(ML307A_RX)
def init_com():
global ML307A_RX
get_com_list()
len = port_list.__len__()
device = port_list[0].device
print(len, device)
serial_open()
thread1 = threading.Thread(target=thread_com_receive)
thread1.start()
COMM.write("AT\r\n".encode("UTF-8"))
time.sleep(0.1)
if ML307A_RX=="OK":
com_jugg()
if __name__ == '__main__':
init_com()
