Question

我试图打乒乓球＆＃34;在一些python代码和arduino代码之间来回信息。我想定期向arduino代码发送两个设定值（例如在分钟内），在arduino和amp;上读取它们。更新变量然后定期将状态信息从arduino发送回python（例如：30秒）。最终python将从mySQL db（后来的dev）发送和提取信息。

现在我无法让信息可靠地来回反弹。我在搜索中找不到任何与此相近的内容，而且我尝试修改的所有内容都无法正常工作。我最近的就是这个（它实际上并没有在发送和接收之间来回切换）：

的Python

#!/usr/bin/python
import serial
import syslog
import time

#The following line is for serial over GPIO
port = '/dev/ttyS0'


ard = serial.Serial(port,9600,timeout=5)

i = 0

while (i < 4):
    # Serial write section

    setTempCar1 = 63
    setTempCar2 = 37
    ard.flush()
    setTemp1 = str(setTempCar1)
    setTemp2 = str(setTempCar2)
    print ("Python value sent: ")
    print (setTemp1)
    ard.write(setTemp1)
    time.sleep(4)

    # Serial read section
    msg = ard.readline()
    print ("Message from arduino: ")
    print (msg)
    i = i + 1
else:
    print "Exiting"
exit()

Arduino的：

// Serial test script

int setPoint = 55;
String readString;

void setup()
{

  Serial.begin(9600);  // initialize serial communications at 9600 bps

}

void loop()
{
  while(!Serial.available()) {}
  // serial read section
  while (Serial.available())
  {
    if (Serial.available() >0)
    {
      char c = Serial.read();  //gets one byte from serial buffer
      readString += c; //makes the string readString
    }
  }

  if (readString.length() >0)
  {
    Serial.print("Arduino received: ");  
    Serial.println(readString); //see what was received
  }

  delay(500);

  // serial write section

  char ard_sends = '1';
  Serial.print("Arduino sends: ");
  Serial.println(ard_sends);
  Serial.print("\n");
  Serial.flush();
}

我最终获得的是重复的相同值（不是实际发送的，不确定它是否是字符串或字节问题）并且没有回到python脚本。非常感谢任何帮助或想法。感谢。

编辑：修改了我目前正在运行的代码，如下所示。 Arduino正在接收由minicom验证的精细和串行通信。但是，在#du;来自arduino的消息之后，python脚本仍会打印一个空行：＆＃34;。

Answer 1

在写入和阅读之间，你不应该在Python中关闭串口。当Arduino响应时，端口仍有可能仍然关闭，在这种情况下数据将丢失。

while running:  
    # Serial write section
    setTempCar1 = 63
    setTempCar2 = 37
    setTemp1 = str(setTempCar1)
    setTemp2 = str(setTempCar2)
    print ("Python value sent: ")
    print (setTemp1)
    ard.write(setTemp1)
    time.sleep(6) # with the port open, the response will be buffered 
                  # so wait a bit longer for response here

    # Serial read section
    msg = ard.read(ard.inWaiting()) # read everything in the input buffer
    print ("Message from arduino: ")
    print (msg)

Python Serial.read函数默认只返回一个字节，因此您需要在循环中调用它或等待数据传输然后读取整个缓冲区。

在Arduino方面，您应该考虑当没有可用数据时loop函数中会发生什么。

void loop()
{
  // serial read section
  while (Serial.available()) // this will be skipped if no data present, leading to
                             // the code sitting in the delay function below
  {
    delay(30);  //delay to allow buffer to fill 
    if (Serial.available() >0)
    {
      char c = Serial.read();  //gets one byte from serial buffer
      readString += c; //makes the string readString
    }
  }

相反，请在loop函数的开头等待，直到数据到达：

void loop()
{
  while (!Serial.available()) {} // wait for data to arrive
  // serial read section
  while (Serial.available())
  {
    // continue as before

编辑2

以下是我与Python的Arduino应用程序接口时的结果：

>>> import serial
>>> s = serial.Serial('/dev/tty.usbmodem1411', 9600, timeout=5)
>>> s.write('2')
1
>>> s.readline()
'Arduino received: 2\r\n'

所以这似乎工作得很好。

在测试你的Python脚本时，似乎问题是当你打开串口时Arduino重置（至少我的Uno没有），所以你需要等待几秒才能启动它。您也只是为响应阅读了一行，所以我也在下面的代码中解决了这一问题：

#!/usr/bin/python
import serial
import syslog
import time

#The following line is for serial over GPIO
port = '/dev/tty.usbmodem1411' # note I'm using Mac OS-X


ard = serial.Serial(port,9600,timeout=5)
time.sleep(2) # wait for Arduino

i = 0

while (i < 4):
    # Serial write section

    setTempCar1 = 63
    setTempCar2 = 37
    ard.flush()
    setTemp1 = str(setTempCar1)
    setTemp2 = str(setTempCar2)
    print ("Python value sent: ")
    print (setTemp1)
    ard.write(setTemp1)
    time.sleep(1) # I shortened this to match the new value in your Arduino code

    # Serial read section
    msg = ard.read(ard.inWaiting()) # read all characters in buffer
    print ("Message from arduino: ")
    print (msg)
    i = i + 1
else:
    print "Exiting"
exit()

现在输出上面的内容：

$ python ardser.py
Python value sent:
63
Message from arduino:
Arduino received: 63
Arduino sends: 1


Python value sent:
63
Message from arduino:
Arduino received: 63
Arduino sends: 1


Python value sent:
63
Message from arduino:
Arduino received: 63
Arduino sends: 1


Python value sent:
63
Message from arduino:
Arduino received: 63
Arduino sends: 1


Exiting

Answer 2

我发现最好使用命令Serial.readString()代替Serial.read()，以获得Arduino的连续I / O。

Answer 3

首先，您必须安装模块调用Serial。为此，请转到python安装文件夹中的Scripts文件夹。如果您使用的是Python 3版本，则通常位于以下位置，

C:\Python34\Scripts

打开该文件夹后，使用Shift键右键单击该文件夹。然后单击“在此处打开命令窗口”。之后，cmd将弹出。在该cmd窗口中编写以下代码，

pip install PySerial

然后按Enter。将安装 PySerial 模块。记住要安装模块，您必须具有INTERNET连接。

成功安装模块后，打开python IDLE并写下下面的代码并运行它。

import serial
# "COM11" is the port that your Arduino board is connected.set it to port that your are using        
ser = serial.Serial("COM11", 9600)
while True:
    cc=str(ser.readline())
    print(cc[2:][:-5])

python到arduino串口读取＆amp;写

3 个答案: