(****************************************************************************
 *  This sample will prompt the user for a voltage between 0 and 10 volts,  *
 *  then calculate the actual voltage based on the resolution of the DAC and*
 *  output the voltage to the desired DAC channel.                          *
 *                                                                          *
 *  Board Configuration:                                                    *
 *   -- The Base Address should be set to the address which will be entered *
 *      during program execution.                                           *
 *   -- Reference voltage for the DACs should be -10V.   (required)         *
 *   -- All remaining jumper settings are irrelevant.                       *
 ****************************************************************************)
program sample1;
uses crt;


var key_entered        :char;


function AskForBaseAddress(OldOne : String) : Word;
const
   Msg : string[4] = '0';
var
   NewOne, Success, Dummy, Error : Word;
   AddrInputPosX, AddrInputPosY : Word;
begin
   if (OldOne = 'OLD') then OldOne := Msg;
   WriteLn('Please enter the Base Address (0000-FFFF) for your card (in hex)');
   WriteLn('or press ENTER for ', OldOne, '.  ');
   Write('>');
   AddrInputPosX := WhereX; AddrInputPosY := WhereY;
   repeat
      GotoXY(AddrInputPosX, AddrInputPosY);
      ClrEol;
      Readln(Msg);
      Val('$' + Msg, NewOne, Error);
      if (error=0) then begin
         Success := 1;
         Dummy := NewOne;
      end else if (Msg = '') then begin
         GotoXY(AddrInputPosX, AddrInputPosY);
         WriteLn(OldOne);
         Msg := OldOne;
         Success := 1;
         Val('$' + Msg, Dummy, Error);
      end;
   until (Success = 1);
   AskForBaseAddress := Dummy;
end;  { end of AskForBaseAddress }




(****************************************************************************
 *  FUNCTION: write_DAC - local routine                                     *
 *   PURPOSE: Prompts the user for DAC number and voltage, then calculates  *
 *            the actual output voltage based on resolution, displays it    *
 *            and writes the value to the DAC.                              *
 ****************************************************************************)
procedure write_DAC(Address : word);

var     counts_entered,volt_value_entered,volt_value_expected  :real;
	dac_number                :word;

begin

(* prompt for the DAC number and desired voltage. *)

   WriteLn;WriteLn;
   repeat
      GotoXY (1,3);
      ClrEol;
      Write('Enter the DAC number (0 through 15 only): ');
      ReadLn(dac_number);
   until (dac_number>=0) and (dac_number<=15);
   WriteLn;WriteLn;WriteLn;
   repeat
      GotoXY (1,7);
      ClrEol;
      Write('Enter a voltage between 0.000v to 9.997v: ');
      ReadLn(volt_value_entered);
   until (volt_value_entered>=0) and (volt_value_entered<=9.997);
   WriteLn;WriteLn;
   volt_value_entered := volt_value_entered / 0.00015259;

   (* compute the digital output needed for this value and the actual voltage
      that will be expected, and display the voltage. *)

   counts_entered:= volt_value_entered;
   volt_value_expected := counts_entered * 0.00015259;
   WriteLn('Due to the 16-bit resolution of the DAC, you should expect');
   WriteLn('to see a voltage of ',volt_value_expected:4:3,'.');

   (* prepare the control word and Write to the DAC *)

   PortW[Address+(2 * dac_number)] := trunc(counts_entered);  (* Write low byte         *)
end; (* write_DAC *)

(****************************************************************************
 *  FUNCTION: main program - global routine                                 *
 *  PURPOSE: Controls overall program execution and determines exit.       *
 ****************************************************************************)
var
  Channel, Address : Word;

BEGIN
   ClrScr;
   WriteLn('                        SAMPLE1.PAS : DA1616                    ');
   WriteLn('                                                                          ');
   WriteLn('  This sample will prompt the user for a voltage between 0 and 10 volts,  ');
   WriteLn('  then calculate the actual voltage based on the resolution of the DAC and');
   WriteLn('  output the voltage to the desired DAC channel.                          ');
   WriteLn;
   WriteLn;
   WriteLn('  Board Configuration:                                                    ');
   WriteLn;
   WriteLn('   -- The Base Address should be set to the address which will be entered ');
   WriteLn('      during program execution.                                           ');
   WriteLn('   -- Reference voltage for the DACs should be -10V.    (required)        ');
   WriteLn('   -- All remaining jumper settings are irrelevant.                       ');
   WriteLn;
   WriteLn;
   Address := AskForBaseAddress('350');
   WriteLn;
   WriteLn;
   WriteLn('Press ENTER to continue');
   ReadLn;

   (* Set all sixteen buffers to 0 *)
   for Channel := 0 to 16 Do PortW[Address + Channel * 2] := 0;

   (* Take card out of simultaneous update mode and update all channels *)
   Channel := Port[Address + 10];
   repeat
      ClrScr;
      write_DAC(Address);
      WriteLn;WriteLn;
      Write('Would you like to output another value (Y or N)? ');
      read(key_entered);
   until ((key_entered = 'N') or (key_entered = 'n'));
   ClrScr;
END. (* main *)