python 自动识别并连接串口

这个属于我项目中一个函数,跟大家分享一下我的思路及最终实现

在编写串口通信工具中,需要实现一个函数,自动找到对应com 口,并且连接该com口,保证后续通信正常
作为初始化过程的一部分。

思路

在win 设备管理器中,经常会出现多个com 口,但并不是每个com 口都是目标设备所链接的。
尝试打开每个com 口,输入enter 按键, 正确的com 口,会有ack log 返回,表明通信 正常

否则,没有任何log 返回,则判断为非目标设备所连接的com 口。

实现

python 自动识别并连接串口_第1张图片
尝试去打开所有com 口,然后发送enter, 如果在一段时间内有返回值,检查com 口收到的字节数,如果非零,则表明找到了对应的com 口。

完整测试代码如下:

import serial
import serial.tools.list_ports
import threading
import binascii
import time
from datetime import datetime

# default value
baunRate = 115200
is_read = False
is_write = False
write_buff = []
sys_buff = []
mSerial = None
callback = None
is_opened = 0
is_registed = 0


class SerialPort:

    def __init__(self,port,buand):

        self.port = serial.Serial(port,buand)
        self.port.close()
        if not self.port.isOpen():
            self.port.open()

        #the index of data_bytes for read operation,私有属性
        #only used in read lines
        self.__read_ptr = 0
        self.__read_head = 0
        #store all read bytes
        # used in read date, read lines
        self.__data_bytes = bytearray()

    def port_open(self):
        if not self.port.isOpen():
            self.port.open()

    def port_close(self):
        self.port.close()

    def send(self):
        global is_write
        global write_buff

        while is_write:
            if len(write_buff):
                msg = write_buff.pop(0)
                msg = msg+"\n"
                cmd = msg.encode()
                try:

                    self.port.write(cmd)
                except:
                    write_buff.clear()
                    is_write = False
        write_buff.clear()

    def read_data(self):
        global is_read
        global is_opened
        byte_cnt = 0
        while is_read:
            try:
                count = self.port.inWaiting()
                if count > 0:
                    rec_str = self.port.read(count)
                    self.__data_bytes = self.__data_bytes+rec_str
                #print("receive:",rec_str.decode())
                    #print(rec_str)
                    byte_cnt += count
                    if not is_opened:
                        is_opened = 1
            #print("累计收到:",byte_cnt)
            #time.sleep(0.5)
                self.read_lines()
            except:
                deinit()


    #将当前所有的数据都读出,读取位置不变,每次读取指针依次移动,不漏数据, 读取行为一直在进行
    def read_lines(self):
        #reset
        line_cnt = 0
        data_len = len(self.__data_bytes)
        #print ("")
        #print ("begin: prt=:", self.__read_ptr, " head =", self.__read_head,"current len =",data_len)
        if self.__read_ptr >=data_len:
            return
        #get all lines in current data_bytes
        while(self.__read_ptr < data_len-1):
            if(self.__data_bytes[self.__read_ptr+1] == 0x0a and self.__data_bytes[self.__read_ptr] == 0x0d):
                tmp = bytearray()
                tmp = self.__data_bytes[self.__read_head:self.__read_ptr]

                try:
                    line = tmp.decode()
                except:
                    self.__read_head = self.__read_ptr + 2
                    self.__read_ptr = self.__read_head
                    continue
                iprint(line)
                line_cnt += 1
                self.__read_head = self.__read_ptr + 2
                self.__read_ptr = self.__read_head
            else:
                self.__read_ptr = self.__read_ptr + 1

def auto_open_serial():
    global baunRate
    global mSerial
    global callback
    global is_registed
    global is_opened
    #reset
    deinit()
    # 列出所有当前的com口
    port_list = list(serial.tools.list_ports.comports())
    port_list_name = []
    #get all com
    if len(port_list) <= 0:
        iprint("the serial port can't find!")
        return False
    else:
        for itms in port_list:
            port_list_name.append(itms.device)
    #try open
    #print(port_list_name)
    for i in port_list_name:
        try:
            mSerial = SerialPort(i,baunRate)
            iprint("try open %s"%i)
            start_task()
            send("")
            #return True
            time.sleep(1)
            if is_opened:
                iprint("connect %s successfully"%i)
                return True
            else:
                deinit()
                if i == port_list_name[len(port_list_name)-1]:
                    iprint("uart don't open")
                    break
                continue
        except:
            iprint(" uart don't open")
    deinit()
    return False

def deinit():
    global mSerial
    global is_write
    global is_read
    global write_buff
    global is_opened

    if mSerial:
        mSerial.port_close()

    is_opened = 0
    is_read = False
    is_write = False
    write_buff = []

    mSerial = None
    time.sleep(1)

def init():
    global mSerial
    global callback
    global is_registed
    global is_opened
    global is_read
    global is_write
    #retry
    retry_time = 0
    while not auto_open_serial():
        if not is_opened:
           iprint("wait for uart connect, retry %s"%str(retry_time))
        else:
            return True
        retry_time += 1
        time.sleep(2)
        if retry_time == 10:
            iprint(" open uart fail")
            return False

def send(msg):
    global mSerial
    global is_write
    global write_buff
    if is_write:
        write_buff.append(msg)

def start_task():
    global mSerial
    global is_write
    global is_read

    if mSerial:
        is_write = True
        t1 = threading.Thread (target=mSerial.send)
        t1.setDaemon (False)
        t1.start ()

        is_read = True
        t2 = threading.Thread (target=mSerial.read_data)
        t2.setDaemon (False)
        t2.start ()

def iprint(msg):
    global callback
    global is_registed

    msg = "[Uart] "+str(msg)
    if is_registed:
        callback.append(msg)
    else:
        print(msg)

def start_sys_cmd():
    global is_registed
    if is_registed:
        t3 = threading.Thread (target=process_receive_sys_cmd)
        t3.setDaemon (False)
        t3.start()

def process_receive_sys_cmd():
    global sys_buff
    global is_registed
    global callback
    #print("process_receive_sys_cmd")
    while is_registed:
        #print ("wait,process_receive_sys_cmd")
        if len(sys_buff):
            #print ("receive,process_receive_sys_cmd")
            line = sys_buff.pop(0)
            if "init" in line:
                if is_opened and is_read and is_write:
                    iprint("already open uart")
                    break
                iprint("start init")
                init()
        if is_opened:
            break
    iprint("Eixt uart sys thread")

def register_cback(list):
    global callback
    global is_registed

    callback = list
    is_registed = 1


def unregister_cback():
    global callback
    callback.clear()

if __name__ == '__main__':

    receive = []
    register_cback(receive)
    sys_buff.append("init")
    start_sys_cmd()

    def process_receive_msg():
        global receive
        while True:
            #print("wait")
            if len(receive):
                #print("receive")
                print(receive.pop(0))

    t = threading.Thread(target=process_receive_msg)
    t.setDaemon(False)
    t.start()






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