[pySerial中的readline（）有时会捕获从Arduino串行端口流式传输的不完整值

Question

[每隔一秒钟，Arduino打印（串行）'当前时间（以毫秒为单位）和Hello world'。在串行监视器上，输出看起来不错。

但是在pySerial中，有时在字符串的中间有换行符。

313113   Hel
lo world
314114   Hello world
315114   Hello world

我的python代码为：

import serial
import time
ser = serial.Serial(port='COM4',
                    baudrate=115200,
                    timeout=0)

while True:
   str = ser.readline()         # read complete line
   str = str.decode()           # decode byte str into Unicode
   str = str.rstrip()           

   if str != "":
      print(str)
   time.sleep(0.01)

我做错了什么？

我的配置：

Python 3.7pySerial 3.4登上Arduino Mega

Answer 1

问题显然似乎是由于Arduino的串行输出尚未完成发送完整数据而在读取数据时读取速度太快引起的。

现在有了此修复程序，pySerial将能够接收完整的数据，并且不会丢失任何数据。主要好处是它可用于任何类型的数据长度，并且睡眠时间非常短。

我已通过下面的代码解决了这个问题。

# This code receives data from serial device and makes sure 
# that full data is received.

# In this case, the serial data always terminates with \n.
# If data received during a single read is incomplete, it re-reads
# and appends the data till the complete data is achieved.

import serial
import time
ser = serial.Serial(port='COM4',
                    baudrate=115200,
                    timeout=0)

print("connected to: " + ser.portstr)

while True:                             # runs this loop forever
    time.sleep(.001)                    # delay of 1ms
    val = ser.readline()                # read complete line from serial output
    while not '\\n'in str(val):         # check if full data is received. 
        # This loop is entered only if serial read value doesn't contain \n
        # which indicates end of a sentence. 
        # str(val) - val is byte where string operation to check `\\n` 
        # can't be performed
        time.sleep(.001)                # delay of 1ms 
        temp = ser.readline()           # check for serial output.
        if not not temp.decode():       # if temp is not empty.
            val = (val.decode()+temp.decode()).encode()
            # requrired to decode, sum, then encode because
            # long values might require multiple passes
    val = val.decode()                  # decoding from bytes
    val = val.strip()                   # stripping leading and trailing spaces.
    print(val)