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CppComPort

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(C++) Access the COM port

When you use Microsoft's Visual C++ check this link: http://msdn2.microsoft.com/en-us/library/aa363195.aspx

You might also use assembler code:

//When you have a LED soldered between GND and DTR this will cause it to flicker.
//A speaker will create a high pitched tone
int main()
{
  while(1)
  {
    //Write 0 to register 4
    asm
    {
      mov dx, 0x3FC //Write to index 4
      mov al, 0     //The value 0
      out dx,al
    }
    //Write 1 to register 4
    asm
    {
      mov dx, 0x3FC //Write to index 4
      mov al, 1     //The value 1
      out dx,al
    }
  }
  return 0;
}

Reading one of seven registers (I know the code is not beautiful or so, so please post a better solution ):

int readRegister(const int& reg) const
{
  char myVal = 0;
  if (reg==0)
  {
    asm
    {
      mov dx, 0x3F8 + 0
      in al, dx
      mov myVal,al
    }
    return myVal;
  }
  if (reg==1)
  {
    asm
    {
      mov dx, 0x3F8 + 1
      in al, dx
      mov myVal,al
    }
    return myVal;
  }
  if (reg==2)
  {
    asm
    {
      mov dx, 0x3F8 + 2
      in al, dx
      mov myVal,al
    }
    return myVal;
  }
  if (reg==3)
  {
    asm
    {
      mov dx, 0x3F8 + 3
      in al, dx
      mov myVal,al
    }
    return myVal;
  }
  if (reg==4)
  {
    asm
    {
      mov dx, 0x3F8 + 4
      in al, dx
      mov myVal,al
    }
    return myVal;
  }
  if (reg==5)
  {
    asm
    {
      mov dx, 0x3F8 + 5
      in al, dx
      mov myVal,al
    }
    return myVal;
  }
  if (reg==6)
  {
    asm
    {
      mov dx, 0x3F8 + 6
      in al, dx
      mov myVal,al
    }
    return myVal;
  }
  assert(!"Should not get here");
  return 0;
}

'COM Port' links

• General

External links

• Beyond Logic: http://www.beyondlogic.org
• Deep Software: http://www.deepsoftware.com/nrcomm

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