使用Pyserial將十六進制串行端口通過串行端口連接到LPC微控制器不起作用

Question

我正在使用Arch Linux，並且未找到任何允許我將文件閃存到我的微控制器的軟件。我學校的閃光文件有一個python文件，當我運行它時，我得到了錯誤消息root：Timed out !.

的代碼：

######## 
# CHANGELOG: 
# 2016-02-15 : Working Skeleton for Flashing a Hex file to SJOne comeplete! 
# 

import string 
import os 
import time 
import struct 
import binascii 
import math 
import serial.serialutil 
import logging 
import sys 
sys.path.append('/usr/lib/python3.5/site-packages/') 
from intelhex import IntelHex 
import serial 

############################################################################### 
################# CONFIGURATION FOR pyFlash - Hyperload ###################### 
############################################################################### 
sDeviceFile = "/dev/ttyUSB0" # Device File Path 
sDeviceBaud = 38400   # Suitable Device Baud Rate 
sHexFilePath = "/SJSU_Dev2/projects/lpc1758_freertos/_build/lpc1758_freertos.hex" 
sGenerateBinary = "y" # "y" - Yes | "n" - No 
############################################################################### 

#### LOGGING OPTIONS #### 
PYFLASH_DEBUG_LOG = "no" # "yes" - Debug Version. "no" - Release Version 
######################### 


if PYFLASH_DEBUG_LOG == "yes": 
    PYFLASH_BUILD_LEVEL = "DEBUG" 
else: 
    PYFLASH_BUILD_LEVEL = "RELEASE" 

if PYFLASH_BUILD_LEVEL == "DEBUG": 
    logging.basicConfig(stream=sys.stdout, level=logging.DEBUG) 
else: 
    logging.basicConfig(stream=sys.stdout, level=logging.INFO) 


# Things to Do: 
# 1. Display Platform Information        [DONE] 
# 2. Enable a Debug/Release Switch        [DONE] 
# 3. Create ~/.pyFlash and store last used options for Flashing [PEND] 
# 4. Handle Exceptions           [PEND] 
# 5. Ensure packing is done based on Endianness     [PEND] 
# 6. Re-write program with classes using this as the backbone. [PEND] 
# 7. Incorporate design decisions keeping the GUI in mind  [PEND] 

# Issues Faced 
# 1. Handling Bytes were hard - Use bytearray for most of the IO related functions. Difference between bytes and bytearray is that the latter is mutable. 
# Bytes are types that are not mutable. Any changes done on them will cause a new alloc + concat and reassigning. 

# Global Defines 

ApplicationVersion = "1.0" 
ToolName = "pyFLASH - HYPERLOAD" 
ToolInfo = "Flashing Tool for SJOne" 
BaudList = [4800, 9600, 19200, 38400] 
ControlWordList = b'\x80\xf8\xfe\xff' 
SpecialChar = {'Dollar' : '$', 'OK' : '!', 'NextLine' : '\n', 'STAR' : '*'} 
sCPUSpeed = 48000000 
sInitialDeviceBaud = 38400 

ByteReference = b'\xff\x55\xaa' 

# Common Util Functions 
def printIntroMessage(): 
    print ("#######################") 
    print (" ", ToolName) 
    print (ToolInfo) 
    print ("#######################") 
    print ("Version : ", ApplicationVersion) 
    print ("Build Type : ", PYFLASH_BUILD_LEVEL) 
    print ("#######################") 

    return 


def printBytes(mymsg): 

    print ("Type info = " + (str)(type(mymsg))) 

    if (type(mymsg) == bytes) or (type(mymsg) == bytearray): 
     for x in mymsg: 
      print ("0x" + '{:x}'.format(x),) 

     print ("") 
     print ("Total Elements = " + (str)(len(mymsg))) 

    elif (type(mymsg) == str): 
     printBytes(bytearray(mymsg)) 

    elif type(mymsg) == int: 

     print ("0x" + '{:x}'.format(mymsg),) 

    else: 
     print (mymsg) 

    return 

def getBoardParameters(descString): 
    boardParametersDict = {'Board' : '', 'BlockSize' : '', 'BootloaderSize' : '', 'FlashSize' : ''} 

    # Parsing String to obtain required Board Parameters 
    boardParametersList = descString.split(':') 

    boardParametersDict['Board'] = boardParametersList[0] 
    boardParametersDict['BlockSize'] = boardParametersList[1] 
    boardParametersDict['BootloaderSize'] = (int(boardParametersList[2]) * 2) 
    boardParametersDict['FlashSize'] = boardParametersList[3] 

    print ("\n***** Board Information ********") 
    print ("Board    = " + (str)(boardParametersDict['Board'])) 
    print ("Block (Chunk) Size = " + (str)(boardParametersDict['BlockSize']) + " bytes") 
    print ("Bootloader Size = " + (str)(boardParametersDict['BootloaderSize']) + " bytes") 
    print ("Flash Size   = " + (str)(boardParametersDict['FlashSize']) + " KBytes") 
    print ("*********************************\n") 

    return boardParametersDict 

def printContent(lContent): 

    logging.debug("--------------------") 
    count = 0; 
    totalCount = 0; 
    for x in lContent: 
     print ('{:2x}'.format(x),) 
     if count >= 10: 
      print ("\n") 
      count = 0 
     else: 
      count = count + 1 
     totalCount = totalCount + 1 

    logging.debug("\n--------------------") 
    logging.debug("Total Count = ", totalCount) 
    logging.debug("--------------------") 

    return 

def getControlWord(baudRate, cpuSpeed): 
    # TODO : Currently using known values. Replace with actual formula 
    logging.debug("Retrieving Control Word") 

    controlWord = ((cpuSpeed/(baudRate * 16)) - 1) 

    return controlWord 

def getPageContent(bArray, blkCount, pageSize): 

    startOffset = blkCount * pageSize 
    endOffset = (startOffset + pageSize - 1) 

    #print "Page Start = ", startOffset, " | Page End = ", str(endOffset) 

    lPageContent = bytearray(pageSize) 
    for x in range(0, pageSize): 
     lPageContent[x] = bArray[x + (blkCount * pageSize)] 

    #print "Length of x = ", x 

    if x != pageSize - 1: 
     raw_input() 

    return lPageContent 


def getChecksum(blocks): 

    # Try older method - Add and Pack into integer. 
    lChecksum = bytearray(1); 
    for x in blocks: 
     lChecksum[0] = (lChecksum[0] + x) % 256 

    return lChecksum[0] 

# Class 

### Main Program ### 

printIntroMessage() 

print (str('-' * (len(sHexFilePath) + 20))) 
print ("Hex File Path = \"" + sHexFilePath + "\"") 
print (str('-' * (len(sHexFilePath) + 20))) 

# Fetching Hex File and Storing 
hexFile = IntelHex(sHexFilePath) 

if sGenerateBinary == "y": 
    # Create a Binary File of this Hex File 
    sBinFilePath= sHexFilePath.replace(".hex", ".bin") 
    logging.debug("Binary File Path : %s", sBinFilePath) 
    hexFile.tofile(sBinFilePath, format='bin') 

# Obtain the actual Binary content from the Hex File 
binArray = hexFile.tobinarray() 

sPort = serial.Serial(
      port = sDeviceFile, 
      baudrate = sInitialDeviceBaud, 
      parity = serial.PARITY_NONE, 
      stopbits = serial.STOPBITS_ONE, 
      bytesize = serial.EIGHTBITS) 

sPort.reset_input_buffer() 
sPort.reset_output_buffer() 
sPort.flush() 

# Setting Initial State of RTS Bit to False 
sPort.rts = False; 

# Reseting the board by toggling DTR 
sPort.dtr = False; 

# Reading a Byte from SJOne 
msg = sPort.read(1) 

if msg is ByteReference[1]: 

    sPort.write(ByteReference[1]) 

    logging.debug("Initial Handshake Initiated! - Received ") 

    msg = sPort.read(1) 

    if msg is ByteReference[2]: 
     logging.debug("Received " + (str)(repr(msg)) + ", Sending Control Word..") 

     lControlWordInteger = getControlWord(sDeviceBaud, sCPUSpeed) 
     lControlWordPacked = struct.pack('<i', lControlWordInteger) 

     msg = sPort.write(bytearray(lControlWordPacked)) 

     if msg != 4: 
      logging.error("Error - Sending control word failed") 
     else: 
      logging.debug("Sending Control Word Successful!") 

      msg = sPort.read(1) 

      if msg != lControlWordPacked[0]: 
       logging.error("Error - Failed to receive Control Word Ack") 
      else: 
       logging.debug("Ack from SJOne received!") 

       if sDeviceBaud != sInitialDeviceBaud: 
        # Switch to new BaudRate here. 
        logging.debug("Requested Baudrate different from Default. Changing Baudrate..") 

        sPort.baudrate = sDeviceBaud 

       else: 
        logging.debug("BaudRate same as Default") 

       # Read the CPU Desc String 
       msg = sPort.read(1) 

       if msg != SpecialChar['Dollar']: 
        logging.error("Failed to read CPU Description String") 
       else: 
        logging.debug("Reading CPU Desc String..") 

        CPUDescString = SpecialChar['Dollar'] 
        while True: 
         msg = sPort.read(1) 

         if msg == SpecialChar['NextLine']: 
          break 

         CPUDescString = CPUDescString + msg 

        logging.debug("CPU Description String = %s", CPUDescString) 

        boardParameters = getBoardParameters(CPUDescString) 

        # Receive OK from SJOne 
        msg = sPort.read(1) 

        if msg != SpecialChar['OK']: 
         logging.error("Error - Failed to Receive OK") 
        else: 
         logging.debug("OK Received! Sending Block") 

        # Send Dummy Blocks - 
        # Update : We can send the actual blocks itself. 


        # Sending Blocks of Binary File 
        totalBlocks = (len(binArray) * 1.0/int(boardParameters['BlockSize'])) 
        logging.debug("Total Blocks = %f", totalBlocks) 

        paddingCount = len(binArray) - ((len(binArray)) % int(boardParameters['BlockSize'])) 
        logging.debug("Total Padding Count = %d", paddingCount) 

        totalBlocks = math.ceil(totalBlocks)  
        print ("Total # of Blocks to be Flashed = ", totalBlocks) 

        # Pad 0's to binArray if required. 
        binArray = bytearray(binArray) 
        binArray += (b'\x00' * paddingCount) 

        blockCount = 0 
        sendDummy = False 
        #sendDummy = True 
        blockContent = bytearray(int(boardParameters['BlockSize'])) 

        if sendDummy == True: 
         logging.debug("FLASHING EMPTY BLOCKS") 
# 
        while blockCount < totalBlocks: 
         print ("--------------------") 

         blockCountPacked = struct.pack('<H', blockCount) 

         msg = sPort.write(blockCountPacked[1]) 
         if msg != 1: 
          logging.error("Error in Sending BlockCountLowAddr") 

         msg = sPort.write(blockCountPacked[0]) 
         if msg != 1: 
          logging.error("Error in Sending BlockCountHiAddr") 

         logging.debug("BlockCounts = %d", blockCount) 

         if sendDummy == False: 
          blockContent = getPageContent(binArray, blockCount, int(boardParameters['BlockSize'])) 

         msg = sPort.write(blockContent) 
         if msg != len(blockContent): 
          logging.error("Error - Failed to sending Data Block Content") 
          break 

         #printContent(blockContent) 

         checksum = bytearray(1) 

         checksum[0] = getChecksum(blockContent) 

         logging.debug("Checksum = %d[0x%x]", checksum[0], checksum[0]) 

         msg = sPort.write(checksum) 
         logging.debug("Size of Block Written = %d", msg) 

         if msg != 1: 
          logging.error("Error - Failed to send Entire Data Block") 

         msg = sPort.read(1) 
         if msg != SpecialChar['OK']: 
          logging.error("Failed to Receive Ack.. Retrying #" + str(blockCount)) 
         else: 
          print ("Block # " + str(blockCount) + " flashed!") 
          blockCount = blockCount + 1 

         print ("--------------------") 

        if blockCount != totalBlocks: 
         logging.error("Error - All Blocks not Flashed") 
         logging.error("Total = " + str(totalBlocks)) 
         logging.error("# of Blocks Flashed = " + str(blockCount)) 
        else: 
         print ("Flashing Successful!") 
         endTxPacked = bytearray(2) 
         endTxPacked[0] = 0xFF 
         endTxPacked[1] = 0xFF 

         msg = sPort.write(bytearray(endTxPacked)) 

         if msg != 2: 
          logging.error("Error in Sending End Of Transaction Signal") 

         msg = sPort.read(1) 
         logging.debug("Received Ack = " + str(msg)) 

         if msg != SpecialChar['STAR']: 
          logging.error("Error - Final Ack Not Received") 

else : 
    logging.error("Timed Out!") 

sPort.baudrate = sInitialDeviceBaud 


sPort.close() 

上半部分建立正確的端口（的/ dev/ttyUSB0）並接通十六進制到二進制，和下半部做閃爍，這是不工作的方面。

端口（/ dev/ttyUSB0）和波特率是正確的。

Answer 1

發生超時，因爲該程序不會從設備讀取的字節預期：

# Reading a Byte from SJOne 
msg = sPort.read(1) 

if msg is ByteReference[1]: 
    # Programming code 
    # ... 
else : 
    logging.error("Timed Out!") 

你應該使用minicom驗證您可以與設備進行通信。如果可以與minicom通信，請嘗試在else子句中輸入msg。

在評論，你說打印msg產生

b'\x00' 

然而，ByteReference被定義爲

ByteReference = b'\xff\x55\xaa' 

這意味着ByteReference[1]應該

b'\x55' 

所以msg呢不符合預期值。這意味着將無法達到執行編程的if子句。