重新打开后，arduino 和 pyserial 之间的串行连接变慢

Posted 2023-02-23

【中文标题】重新打开后，arduino 和 pyserial 之间的串行连接变慢

【英文标题】：Serial connection between arduino and pyserial slows down after reopening

【发布时间】：2019-03-09 10:32:11

【问题描述】：

在使用 arduino 和 pyserial 之间的串行连接时，我偶然发现了一个问题，我需要您的帮助：

当我第一次使用串行连接时，它比我再次使用串行连接时快得多。

这是一个最简单的例子：

Arduino 代码：

void setup() 
  Serial.begin(9600);
  Serial.println("Arduino ready"); // Print when Arduino ready


void loop() 
  // send data only when you receive data:
  if(Serial.available() > 0) 
      Serial.read();
      Serial.println(' ');
  
  delay(1); // delay in between reads for stability

Python 代码：

import serial
import time

ser = serial.Serial('COM5',9600,timeout=1)
print(ser.readline()) # Wait until Arduino is ready

for i in range(1,10):
    tic = time.time() # Start timer

    ser.write(b' ')
    ser.readline()

    toc = time.time() # Log time
    print("Serial write / read took %7.4f ms" % ((toc-tic)*1000))

ser.close()

第一次运行python代码：

b'Arduino ready\r\n'
Serial write / read took  5.9998 ms
Serial write / read took  6.0000 ms
Serial write / read took  7.0000 ms
Serial write / read took  5.9998 ms
Serial write / read took  6.0003 ms
Serial write / read took  5.9998 ms
Serial write / read took  6.0000 ms
Serial write / read took  7.0002 ms
Serial write / read took  5.9998 ms

再次运行python代码：

b'Arduino ready\r\n'
Serial write / read took 27.9999 ms
Serial write / read took 29.0003 ms
Serial write / read took 27.9999 ms
Serial write / read took 28.0001 ms
Serial write / read took 27.9999 ms
Serial write / read took 29.0000 ms
Serial write / read took 27.9999 ms
Serial write / read took 28.0001 ms
Serial write / read took 27.9999 ms

恢复串行连接速度的操作：

在 arduino 和 pc 之间拔下 / 插入 usb 电缆 重新编程arduino

通过重置按钮重置 arduino 不会恢复串行连接。

任何想法如何在重新打开连接时达到第一个连接的连接速度？

我正在使用 python 3.6 和 pyserial 3.4。 您需要更多信息吗？

提前致谢！

【参考方案1】：

当我将串行波特率从 9600 增加到 28800 时，问题不再出现。

我还发现，这个问题只发生在我的 Arudino Uno 克隆上。当我使用原始的 Arudino Uno 时，串行连接速度在波特率为 9600 时不会降低。