树莓派Python服务器未发送串行读写命令

Question

我有两台服务器（用Python写的），它们在处理树莓派上的串口通信时几乎是一样的。不过，一台能正常工作，另一台却不行，我找不到问题出在哪里。我连接了一个逻辑分析仪，发现第一台服务器在串口通信时能正确触发接收和发送信号，但第二台服务器却什么都不触发。

首先是第一台（能工作的）服务器，代码简化到只显示串口部分：

import socket
import sys
import RPi.GPIO as GPIO
from serial import Serial

#HOST = ' ' # Symbolic name meaning all available interfaces
PORT = 8888 # Arbitrary non-privleged port
ser = 0

#accepts a command as a string, parameters separated by white space
def processData( data ):
    print ( "cmd : " + data).strip()
    parseData = data.split(" ")
    cmdLength = len(parseData)
    cmd = parseData[0]

    if cmd == "digitalWritePin":
        pin = parseData[1]
        state = parseData[2]
        #GPIO.setup(pin, GPIO.OUT) # SHOULD HAVE ALREADY BEEN DONE W/ A CONFIG!!!
        if state == '1':
            GPIO.output(int(pin), True)
        elif state == "0":
            GPIO.output(int(pin), False)
    elif cmd == "serialConfig":
        baudRate = int(parseData[1])
        timeOut = int(parseData[2])
        global ser
        ser = Serial('/dev/ttyAMA0', baudRate, timeout=timeOut)
    elif cmd == "serialWrite":
        serialcmd = parseData[1]
        writeBuff = data.split("serialWrite")
        #print writeBuff[1].strip(" ")
        ser.write(writeBuff[1].strip(" "))
    elif cmd == "serialReadLine":
        print "serial read:"
        response = ser.readline()
        print response
        conn.sendall(response)
        print "read done"

    return

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print 'Socket created'
s.bind((HOST,PORT))
print 'Socket bind complete'

s.listen(10)    #parameter: backlog, controls number of connections that are 'queued'
print 'Socket now listening'

#Function f or handling connections. this will be used to create threads
def clientthread(conn):
    #sending message to connected client        
    try:
        while True:
            data = conn.recv(1024)
            if not data:
                break
            processData( data )

        #out of the loop
        conn.close()
    except socket.error , msg:
        print 'Recv failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]

while 1:
    #wait to accept a connection - blocking call
    conn, addr = s.accept()
    print 'Connected with ' + addr[0] + ':' + str(addr[1])

    #start new thread takes 1st argument as a function name to be run
    #second is the tuple of arguments to the function
    start_new_thread(clientthread,(conn,))

s.close

其中最重要的部分是：

    ser = Serial('/dev/ttyAMA0', baudRate, timeout=timeOut)

还有el/if块中的串口配置、读取和写入部分。

然后是第二台（不工作的）服务器：

import socket
import sys
from time import sleep
from serial import Serial
from thread import *
import binascii

#HOST = ' ' # Symbolic name meaning all available interfaces
HOST = '10.1.10.28'
PORT = 8889 # Arbitrary non-privleged port


s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print 'Socket created'

try:
    s.bind((HOST,PORT))
except socket.error , msg:
    print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
    sys.exit()

print 'Socket bind complete'

s.listen(10)    #parameter: backlog, controls number of connections that are 'queued'
print 'Socket now listening'

ser = Serial('/dev/ttyAMA0', baudrate = 115200, timeout= 10)
#ser.open #--- uncommenting this does not make a difference 

#Function f or handling connections. this will be used to create threads
def clientthread(conn):

    #infinite loop so the function does not terminate and thread does not end
    try:
        while True:
            print  "step 1"
            first = conn.recv(1)
            print  "step 2"
            if not first:
                break
            hextFirst = hex( ord(first) )
            print hextFirst
            if hextFirst == '0xff':
                print  "step 3"
                #ser.write(hextFirst)           #send 0xff (converted)
                ser.write(first)                #send 0xff (orignal)

                length = conn.recv(1)               #get length
                hextLength = hex( ord(length) )     #convert length
                intlength = ord(length)
                print "hextLength: " + hextLength
                print "step 4"
                #ser.write(hextLength)          #send length (converted)
                ser.write(length)               #send length (original)
                cmd = 0
                if ord(length) == 0:
                    cmd = conn.recv(13)
                else:
                    cmd = conn.recv(ord(length)-2)

                hextCmd = binascii.b2a_hex(cmd)

                print cmd
                print "hextCmd: " + hextCmd
                #ser.write(hextCmd)         #send cmd (converted)
                ser.write(cmd)              #send cmd (original)

                #sleep(1)
                response = ser.read(1)          #get response
                #hextResponse = hex(ord(response))

                print "serial resp: " + response
                conn.sendall(response)          #send response to LV
                print "step 5"
            print "step 6"
            sleep(10)

        #out of the loop
        conn.close()
    except socket.error , msg:
        print 'Recv failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]

try:
    while 1:
        #wait to accept a connection - blocking call
        conn, addr = s.accept()
        print 'Connected with ' + addr[0] + ':' + str(addr[1])

        #start new thread takes 1st argument as a function name to be run
        #second is the tuple of arguments to the function
        start_new_thread(clientthread,(conn,))

    s.close
except KeyboardInterrupt:
    ser.close
    s.close
    print "Exiting: Keyboard Interrupt"

我知道这段代码看起来很多，但你可以忽略大部分内容。我只是想知道在串口配置和写入部分出了什么问题。正如我最开始说的，问题在于逻辑分析仪没有检测到第二台服务器的任何串口通信，而第一台服务器却正常工作。

服务器配置数据传输串口通信树莓派硬件调试串口读取串口写入逻辑分析仪

树莓派Python服务器未发送串行读写命令

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