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Support Forum » Communication with computer

July 09, 2011
by bhovik
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Hi all, I am new to Programming and microelectronics. Could somebody send me code example how to send data through usb to nerdkit and read from usb for example temperature. Thank you very much.. I think it will be a lot of help for starters.

July 09, 2011
by Rick_S
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The tempsensor project sends the temperature through the serial connection to your computer.

July 09, 2011
by bhovik
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I am having trouble reading it using USB. I would like to know How to communicate using USB

July 09, 2011
by Rick_S
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You can communicate through the USB to serial adapter that came with your NerdKit. Direct communications through USB is not something a novice is going to do and would require an extensive programming knowledge.

July 09, 2011
by missle3944
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Just use hyperterminal or putty and point it to your com port

July 09, 2011
by bhovik
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I NEED SIMPLE CODE. like in python but in C or C++ to read from serial port. In Python they have serial package. Does such package exist in C or C++?

July 09, 2011
by Noter
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There's not a lot of simple about using the serial port from C or C++ under windows ... here's some functions to make it easier:

DCB dcb;
HANDLE hCom;
COMMTIMEOUTS cTimeout;
BOOL fSuccess;
TCHAR *pcCommPort = TEXT("COM1"); //  Most systems have a COM1 port

void PrintCommState(DCB dcb, char *port){
    //  Print some of the DCB structure values
    printf("\nPort = %s, BaudRate = %d, ByteSize = %d, Parity = %d, StopBits = %d\n", 
        port,
        dcb.BaudRate, 
        dcb.ByteSize, 
        dcb.Parity,
        dcb.StopBits
        );
}

int OpenCommPort(char *port, char *baud){
  //  Open a handle to the specified com port.
   hCom = CreateFile((LPCTSTR) port,
                    GENERIC_READ | GENERIC_WRITE,
                    0,    //  must be opened with exclusive-access
                    NULL, //  default security attributes
                    OPEN_EXISTING, //  must use OPEN_EXISTING
                    0,    //  not overlapped I/O
                    NULL  //  hTemplate must be NULL for comm devices
                    );

   if (hCom == INVALID_HANDLE_VALUE) 
   {
       //  Handle the error.
       printf ("CreateFile failed with error %d.\n", GetLastError());
       return (1);
   }

   //  Initialize the DCB structure.
   ZeroMemory(&dcb, sizeof(DCB));
   dcb.DCBlength = sizeof(DCB);

   //  Build on the current configuration by first retrieving all current
   //  settings.
   fSuccess = GetCommState(hCom, &dcb);

   if (!fSuccess) 
   {
      //  Handle the error.
      printf ("GetCommState failed with error %d.\n", GetLastError());
      return (2);
   }

   //PrintCommState(dcb);       //  Output to console

   //  Fill in some DCB values and set the com state: 
   //  57,600 bps, 8 data bits, no parity, and 1 stop bit.
   dcb.BaudRate = atol(baud);     //  baud rate
   dcb.ByteSize = 8;             //  data size, xmit and rcv
   dcb.Parity   = NOPARITY;      //  parity bit
   dcb.StopBits = ONESTOPBIT;    //  stop bit

   dcb.fBinary=true;
   dcb.fNull=false;
   dcb.fTXContinueOnXoff=false;
   dcb.fRtsControl=RTS_CONTROL_DISABLE;
   dcb.fDsrSensitivity=false;
   dcb.fDtrControl=DTR_CONTROL_DISABLE;
   dcb.fOutX=false;
   dcb.fInX=false;
   dcb.fOutxCtsFlow=false;
   dcb.fOutxDsrFlow=false;

   fSuccess = SetCommState(hCom, &dcb);

   if (!fSuccess) 
   {
      //  Handle the error.
      printf ("SetCommState failed with error %d.\n", GetLastError());
      return (3);
   }

   //  Get the comm config again.
   fSuccess = GetCommState(hCom, &dcb);

   if (!fSuccess) 
   {
      //  Handle the error.
      printf ("GetCommState failed with error %d.\n", GetLastError());
      return (2);
   }

   PrintCommState(dcb,port);       //  Output to console

   //printf ("Serial port %s successfully reconfigured.\n", port);

    return 0;
}

int SetCommTimeout(int timeout_ms){
    cTimeout.ReadIntervalTimeout = MAXDWORD;
    cTimeout.ReadTotalTimeoutConstant = timeout_ms;
    cTimeout.ReadTotalTimeoutMultiplier = MAXDWORD;
    cTimeout.WriteTotalTimeoutConstant = 0;
    cTimeout.WriteTotalTimeoutMultiplier = 0;
    fSuccess=SetCommTimeouts(hCom, &cTimeout);
    if (!fSuccess){
        printf ("SetCommTimeouts failed with error %d.\n", GetLastError());
        return (1);
    }
    return 0;
}

int CloseCommPort(){
    fSuccess=CloseHandle(hCom);
    if (!fSuccess){
        printf ("CloseHandle failed with error %d.\n", GetLastError());
        return (1);
    }
    return 0;
}

int PutCommChar(UCHAR chrOut){
    unsigned long bytesWritten;
    fSuccess=WriteFile(hCom,&chrOut,1,&bytesWritten,0);
    if (bytesWritten!=1){
        printf ("WriteFile wrote %d bytes.\n", bytesWritten);
        return (2);
    }
    if (!fSuccess){
        printf ("WriteFile failed with error %d.\n", GetLastError());
        return (1);
    }
//  printf(">>%02X\n",chrOut);
    return 0;
}

int GetCommChar(UCHAR *chrIn){
    unsigned long bytesRead;
    fSuccess=ReadFile(hCom,chrIn,1,&bytesRead,0);
    if (!fSuccess){
        printf ("ReadFile failed with error %d.\n", GetLastError());
        return (1);
    }
    if (bytesRead!=1){
        printf ("timeout on read port %d\n",bytesRead);
        return (2);
    }
//  printf("<<%02X\n",*chrIn);
    return 0;
}
July 09, 2011
by bhovik
bhovik's Avatar

Thank You very much. I will try..

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