使用Node.js与Arduino进行串行通信

Question

Im trying to control the arduino via using nodejs. My problem is that im trying to write an interger to the arduino but the value won't register. Can any1 help ?

The node.js serial communication code:

var serialport = require("serialport");
var SerialPort = serialport.SerialPort;

var serialPort = new SerialPort("/dev/cu.usbmodem14131", {
  baudrate: 9600,
  parser: serialport.parsers.readline("\n")
});

serialPort.on("open", function () {
  console.log('open');
  serialPort.write("45/r/n")            // wrinting offset value to the arduino 
  serialPort.on('data', function(data) {
    console.log(data);
  });
});

Here the arduino code"

 #include <Wire.h>

int offset = 0; 
String inString = "";

void setup()
{
  Serial.begin(9600);
  delay(100);
}

void loop(){

  Serial.println(offset); //printing the offset 

  while (Serial.available() > 0) {
    int inChar = Serial.read();
      // convert the incoming byte to a char
      // and add it to the string:
      inString += (char)inChar;

    // if you get a newline, print the string,
    // then the string's value:
    if (inChar == '\n') {
      Serial.print("Offset:");
      Serial.println(inString.toInt());
      offset = inString.toInt();
      // clear the string for new input:
      inString = "";
    }
  }
delay(1000);  

}

I'm not really sure if i'm writing the value the wrong way or receiving it wrong, but arduino code work fine if I manually enter the value in the arduino IDE.

Thank you.

Answer 1

I'm not sure about your nodejs code but I think there is an issue with the arduino routine. I did notice your nodejs routine is sending /r/n and the Arduino routine is only looking for /n.

The while loop you have can completely execute in less then one serial character time so it may be adding 1 second delays between characters.

I would structure it to stay in the while loop until a newline is received. Following example has not been compiled, but demostrates the concept. It also filters out the '/r' character.

int inChar;
void loop(){ 
    // clear the string for new input:
    inString ="";         
    inChar=0;

    while (inchar!= '\n') {
        while (Serial.available() > 0) { 
            inchar = Serial.read();
            // do you need to filter the '/r' for it to work correctly?
            if (inchar != '/r') {
                // convert the incoming byte to a char
                // and add it to the string:
                inString += (char)inChar;
            }
        }
    }

    // when you receive a newline, print the label and 
    // the string's value:        
    Serial.print("Offset:");
    Serial.println(inString.toInt());
    offset = inString.toInt();


    delay(1000);  
}