python到arduino串行读取

Question

我试图在一些python代码和arduino代码之间来回“乒乓”信息。我想定期向arduino代码发送两个设定点（例如，在分钟内），在arduino上读取它们

现在，我无法获得可靠的信息来来回跳转。我在搜索中没有找到任何与此类似的内容，我试图修改的所有内容都不起作用。最接近我的是这个（实际上它并没有在发送和接收之间来回切换）：

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()

阿杜伊诺：

// 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();
}

我最终得到的只是重复的相同值（不是实际发送的值，不确定是字符串还是字节问题），而没有返回到python脚本。非常感谢您的任何帮助或想法。谢谢

编辑：根据下面的建议修改了我目前正在运行的代码。Arduino正在接收由minicom验证的精细和串行通信。但是python脚本仍然在“来自arduino的消息：”后面打印一个空行。

Answer 1

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

Answer 2

首先，您必须安装一个模块调用串行。要做到这一点，请转到位于python installed文件夹中的call Scripts文件夹。如果您使用的是Python 3版本，它通常位于下面的位置，

C:\Python34\Scripts  

一旦你打开该文件夹右键单击该文件夹与Shift键。然后点击这里打开命令窗口。之后cmd将弹出。在该cmd窗口中编写以下代码，

pip install PySerial

然后按回车键。之后将安装PySerial模块。请记住，安装模块时必须连接互联网。

成功安装模块后，打开python IDLE，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])   

Answer 3

在Python中，不应该在写入和读取之间关闭串行端口。当Arduino响应时，端口仍有可能关闭，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)

PythonSerial.read函数默认情况下只返回一个字节，因此您需要循环调用它，或者等待数据传输，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，在您的循环函数中会发生什么。

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，在循环函数开始时等待，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

以下是我从Python与Arduino应用程序交互时得到的信息：

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

这样看来效果不错。

在测试Python脚本时，问题似乎是当您打开串行端口时Arduino会重置（至少我的Uno会重置），因此您需要等待几秒钟才能启动它。对于响应，您也只读取了一行，因此我在下面的代码中也修复了这一点：

#!/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()

下面是上面的输出：

$ 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