Serial.Available() appears to be always empty when sending data from C# [Solved]

Projects Programming
1

I currently have an RGB LED connected to my arduino uno. I have just started learning Arduino. Everything works fine in general, and am using code as per the adafruit tutorial. When I interact with the Arduino through the Arduino IDE's own serial monitor, everything works fine. The issue is that I am trying to use C# to control the LED. However, the Arduino is never even getting past the if(Serial.available() > 0) line. My code is below:

C# winforms

public partial class Form1 : Form
    {
        static SerialPort _serialPort;
        public Form1()
        {
            InitializeComponent();
            
        }



        private void btnSend_Click(object sender, EventArgs e)
        {
            _serialPort = new SerialPort();
            _serialPort.PortName = "COM6";//Set your board COM
            _serialPort.BaudRate = 9600;
            _serialPort.Open();
            byte[] sendBuf = { (byte)numRed.Value, (byte)numGreen.Value, (byte)numBlue.Value };
            _serialPort.Write(sendBuf, 0, 3);
            _serialPort.Close();
        }
    }

Arduino sketch:

/*
Adafruit Arduino - Lesson 3. RGB LED
*/
 
int redPin = 9;
int greenPin = 10;
int bluePin = 11;
 
//uncomment this line if using a Common Anode LED
#define COMMON_ANODE
 
void setup()
{
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);  
  setColor(0,255,0);
}
 
void loop()
{
  if(Serial.available()){
    setColor(50,50,0);//To see if we even get here
    delay(500); // so I can see the LED...
    char bytes[3];
    for(int i=0;i<3;i++){
      char ch = Serial.read();
      bytes[i]=ch;
      setColor(ch,0,0);
      delay(500);
      setColor(0,0,0);
    }
    setColor(bytes[0],bytes[1],bytes[2]);
  }
}
 
void setColor(int red, int green, int blue)
{
  #ifdef COMMON_ANODE
    red = 255 - red;
    green = 255 - green;
    blue = 255 - blue;
  #endif
  analogWrite(redPin, red);
  analogWrite(greenPin, green);
  analogWrite(bluePin, blue);  
}

Furthermore, when I hit the "send" button on my form, the LED on my arduino labeled "TX" lights up momentarily.

Thanks, hopefully we can figure out why it doesnt work with C# but still works with the IDE Monitor.

2

I'm surprised that it works with the serial monitor... You never call Serial.begin()

3

There should be a Serial.begin(baud) in setup() of the Arduino code to initialize the serial port.

4

AHHHH I feel stupid now, I removed that line as earlier I was having trouble with C# throwing an error for not having permission to COM6. Thanks guys, it works now. Sorry about that - as I said, I am very new.

5

Another note: I changed the Arduino sketch to the following code for it to work properly with the C#

/*
Adafruit Arduino - Lesson 3. RGB LED
*/
 
int redPin = 9;
int greenPin = 10;
int bluePin = 11;
 
//uncomment this line if using a Common Anode LED
#define COMMON_ANODE
 
void setup()
{
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);  
  setColor(0,255,0);
  Serial.begin(9600);
}
 
void loop()
{
  if(Serial.available()>=3){
    char bytes[3];
    for(int i=0;i<3;i++){
      char ch = Serial.read();
      bytes[i]=ch;
    }
    setColor(bytes[0],bytes[1],bytes[2]);
  }
}
 
void setColor(int red, int green, int blue)
{
  #ifdef COMMON_ANODE
    red = 255 - red;
    green = 255 - green;
    blue = 255 - blue;
  #endif
  analogWrite(redPin, red);
  analogWrite(greenPin, green);
  analogWrite(bluePin, blue);  
}

This ensures that the full set of bytes is always there upon reading. Makes for a neat little program!

6

I'm thinking you mean c++ not c#. From what I know, Arduinos don't do c#.

But I'm wrong a lot..

-jim lee