Read arduino Serial.Write with C#

Question

I have an Arduino that send on serial port some information revealed by analogical pin. Anyway, in the Arduino code (that I can not modify) is used Serial.write() instead of Serial.print() in order to print a buffer of char. As a consequence, if in my C# software I read the information with a "simple" ReadLine(), the data are incomprehensible. How can I read these type of data with C#?

It is the Arduino code:

#include <compat/deprecated.h>
#include <FlexiTimer2.h>

#define TIMER2VAL (1024/256)       // 256Hz - frequency                    
volatile unsigned char myBuff[8];
volatile unsigned char c=0;
volatile unsigned int myRead=0;
volatile unsigned char mych=0;
volatile unsigned char i;

void setup() {
 pinMode(9, OUTPUT);

noInterrupts();

 myBuff[0] = 0xa5;    //START 0
 myBuff[1] = 0x5a;    //START 1
 myBuff[2] = 2;       //myInformation
 myBuff[3] = 0;       //COUNTER
 myBuff[4] = 0x02;    //CH1 HB
 myBuff[5] = 0x00;    //CH1 LB
 myBuff[6] = 0x02;    //CH2 HB
 myBuff[7] = 0x00;    //CH2 LB
 myBuff[8] = 0x01;    //END


  FlexiTimer2::set(TIMER2VAL, Timer2);
 FlexiTimer2::start();

  Serial.begin(57600);
 interrupts(); 
}

void Timer2()
{
  for(mych=0;mych<2;mych++){
    myRead= analogRead(mych);
    myBuff[4+mych] = ((unsigned char)((myRead & 0xFF00) >> 8));  // Write HB
    myBuff[5+mych] = ((unsigned char)(myRead & 0x00FF)); // Write LB
  }

  // SEND
  for(i=0;i<8;i++){
    Serial.write(myBuff[i]);
  }

  myBuff[3]++;

}

void loop() {

 __asm__ __volatile__ ("sleep");

}

And this is the C# method that read from serial port

public void StartRead()
    {
        msp.Open(); //Open the serial port

        while (!t_suspend)
        {
            i++;
            String r = msp.ReadLine();
            Console.WriteLine(i + ": " + r);
        }
    }

EDIT: I would as output an array of string that correspond to the data of Arduino output. If I record everything as an array of byte, I have not the information about start and the end of the array. I can edit the code as:

public void StartRead()
    {
        msp.Open(); //Open the serial port
        ASCIIEncoding ascii = new ASCIIEncoding();
        while (!t_suspend)
        {
            i++;
            int r = msp.ReadByte();
            String s = ascii.getString((byte)r); // here there is an error, it require an array byte[] and not a single byte
            Console.WriteLine(i + ": " + r);
        }
    }

How I can have the same Arduino array value (but as a String) in my C# software, considering that the starting value is every time 0xa5 and the end is 0x01.

Because Arduino send sigle bytes, you have to read single bytes ReadByte(). — H.G. Sandhagen
– H.G. Sandhagen, Commented Dec 22, 2016 at 15:31
Ok, but the output is a char. If I use ReadByte() it return an integer, and I do not know how to cast this integer into a char. — youngz
– youngz, Commented Dec 22, 2016 at 15:40
ReadLine() reads a line that ends with a newline character. You are just sending 8 bytes that aren't necessarily all printable characters, so I don't know why are you expecting it to be comprehensible. — gre_gor
– gre_gor, Commented Dec 22, 2016 at 16:23
Also both your analog channels are writing to myBuff[5] and none to myBuff[7]. — gre_gor
– gre_gor, Commented Dec 22, 2016 at 16:24

H.G. Sandhagen · Accepted Answer · 2016-12-25 09:37:07Z

1

Arduino sends a telegram of several bytes. You can read it into a byte array:

byte[] telegram = byte[msp.BytesToRead];
msp.Read(telegram, 0, msp.BytesToRead);

To get the data from the byte array you have to interpret the bytes (See example below). Of course you could create a string from the properties of the Telegram class:

    class Telegram {
    public Telegram(byte[] tel) {
        // Check start bytes ( 0xa5, 0x5a );
        Info = tel[2];
        Counter = tel[3];
        Channel1 = BitConverter.ToInt16(new byte[] { tel[5], tel[4] }, 0); // Switch lo/hi byte
        Channel2 = BitConverter.ToInt16(new byte[] { tel[7], tel[6] }, 0);// Switch lo/hi byte
        // check tel[8] == 1 for end of telegram
     }    
     public int Info { get; private set; }
     public int Counter { get; private set; }
     public int Channel1 { get; private set; }
     public int Channel2 { get; private set; }
}

edited Dec 25, 2016 at 9:37

answered Dec 22, 2016 at 16:03

H.G. Sandhagen

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