Question

我正在使用串口从微控制器获取数据。我的问题是，如果我告诉MCU每20毫秒发送一次数据，一些数据就会被破坏。例如，如果MCU发送sin（时间），你会期望所有数据的范围从-1到1，但我最终得到-1到100的范围（尽管我得到的大部分是在-1之间）到1）。不幸的是，我不会总是知道将要发送到计算机的内容，它可能会有很大差异，我需要能够相信python告诉我它正在接收的内容。 Python和串口是否有时间限制，如果是这样的话是什么？或者有没有办法更可靠地获取数据？我原本以为这只是一个问题，通信被分成几个块（MCU发送：xxxx | xxxx | xxxx和python读取xxx和x | xxxx |和xxxx），我已经处理过了。这是我用来从串口获取东西的代码：

import serial
import serial.tools.list_ports as det
import os
import datetime
from time import gmtime, strftime
import csv


######################### Functions #########################
## Find letter or character in string
def find(s, ch):
    return [i for i, ltr in enumerate(s) if ltr == ch]

## Find string in string
def find_str(s, char):
    index = 0

    if char in s:
        c = char[0]
        for ch in s:
            if ch == c:
                if s[index:index+len(char)] == char:
                    return index

            index += 1

    return -1

## Data saving
def DataSave(x, data):
    #for i in range(x):
     #   DATALISTS[i].append( int( a[ find(buffer,"|")[i] : find(buffer,"|")[i+1] ] ) )
    save = open(x, 'a')
    save.write(data + "\n")
    save.close()
######################### End #########################

######################### Filter #########################
First = True
Plot = True
NumberOfDataPoints = 1
currupt = []
TimeStamp = []
repeat = True

def GetDATA( file, path, port, baud ):
    File = True
    First = True
    Plot = True
    NumberOfDataPoints = 1
    currupt = []
    TimeStamp = []
    repeat = True
    try:
        ser = serial.Serial(port, baud, timeout = 1)
    except FileNotFoundError:
        pass
    while repeat:
        x = ser.inWaiting()
        # only read when something is in buffer
        if x:

            # convert serial.read to a string and remove b' and ' from the beginning and end, respectively
            buffer = str (ser.read(x))
            buffer = buffer[2:][:-1]
            # Gets the time and appends to TimeStamp list
            TimeStamp.append (datetime.datetime.now())
            # Comfirm all data is received, if data is added to the buffer currupt
            lineEnd = ['\\r','\\n']
            # If there is no \r and/or \n in buffer, add buffer to currupt list
            if not any(word in buffer for word in lineEnd) :
                currupt.append(buffer)
            # If \r and/or \n in buffer print buffer 
            # If there is data in currupt list, buffer becomes data in currupt + buffer
            if any(word in buffer for word in lineEnd):
                if len(currupt) is not 0:
                    buffer = ''.join(currupt) + buffer
                del currupt[:]
                # Remove \r and \n from buffer
                while any(word in buffer for word in lineEnd):
                    for i in range(len(lineEnd)):
                        if lineEnd[i] in buffer:
                            buffer = buffer [: find_str(buffer, lineEnd[i] ) ]
                if First:
                    buffer = ''
                    del TimeStamp[:]
                    First = False
                    Plot = True
                # makes sure that there is something to write
                if len(buffer) is not 0:
                    # Set of one datapoint
                    if '|'  not in buffer:
                        if File is not False:
                            datafile=os.path.join(os.path.expanduser('~'), path, file)
                            DataSave(datafile, str(TimeStamp[0]) + '|' + buffer +'|')
                        #print(TimeStamp[0], buffer)
                        del TimeStamp[:]


## unused            
def SetDataPoints(file, path, port):
    GetDATA( file, path, port, False )
    return NumberOfDataPoints

python串行获取数据错误

0 个答案: