(****************************************************************************
 *                     Pascal SAMPLE #1: SAMPLE1.PAS                        *
 *                                                                          *
 *  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.                          *
 *                                                                          *
 *  The following setup of the board is expected:                           *
 *      -- Reference voltage for the DACs should be -10V.                   *
 *                                                                          *
 ****************************************************************************)


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

   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.                              *
 *                                                                          *
 *     INPUT: None.                                                         *
 *                                                                          *
 *     CALLS: None.                                                         *
 *                                                                          *
 *    OUTPUT: None.                                                         *
 *                                                                          *
 ****************************************************************************)

Procedure write_DAC(Address:word);

var
   volt_value_expected,volt_value_entered  :real;
   counts_entered,dac_number       :word;
   ch  :char;
   code :integer;
begin

   (* prompt for the DAC number and desired voltage. *)
   WriteLn;WriteLn;
   repeat
      GotoXY (1,3);
      ClrEol;
      Write('Enter the DAC number you wish to output to (0 or 3 only): ');
      ch := ReadKey;
      Writeln(ch);
      val(ch,dac_number,code);
   until (dac_number>=0) and (dac_number<=3);
   WriteLn;WriteLn;WriteLn;
   repeat
      GotoXY (1,7);
      ClrEol;
      WriteLn('If your card is not set for 0-10V DAC outputs,');
      WriteLn(' the value will be proportional.');
      Write('Enter a voltage between 0.000V to 9.97V: ');
      ReadLn(volt_value_entered);
   until (volt_value_entered>=0) and (volt_value_entered<=9.997);
   WriteLn;WriteLn;

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

   counts_entered := trunc(volt_value_entered/0.002441);
   volt_value_expected := counts_entered * 0.002441;
   WriteLn('Due to the 12-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+4+(2*dac_number)] := counts_entered;
end; (* write_DAC *)

(****************************************************************************
 *                                                                          *
 *  FUNCTION: main program - global routine                                 *
 *                                                                          *
 *   PURPOSE: Controls overall program execution and determines exit.       *
 *                                                                          *
 *     INPUT: None.                                                         *
 *                                                                          *
 *     CALLS: None.                                                         *
 *                                                                          *
 *    OUTPUT: None.                                                         *
 *                                                                          *
 ****************************************************************************)

var
   Address:word;

begin
   ClrScr;
   WriteLn('                     Pascal SAMPLE #1: SAMPLE1.PAS                        ');
   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('  Board Configuration:                           ');
   WriteLn;
   WriteLn('  -- The Base Address should be set to the address which will');
   WriteLn('     be entered during program execution.');
   WriteLn('  -- DACs should be in the 10V unipolar mode.');
   WriteLn('     -- If the DAC''s are in any other mode, the values will');
   WriteLn('        be proportionally incorrect.');
   WriteLn;
   WriteLn;
   WriteLn;
   Address := AskForBaseAddress('300');
   Port[Address+4] := 0;     { set DAC0 to 0 volts }
   Port[Address+6] := 0;     { set DAC1 to 0 volts }
   Port[Address+8] := 0;     { set DAC2 to 0 volts }
   Port[Address+$0a] := 0;   { set DAC3 to 0 volts }
   Port[Address+$18] := 1; {Enable the DACS for output}
   WriteLn;
   repeat
      ClrScr;
      write_DAC(Address);
      WriteLn;WriteLn;
      Write('Would you like to output another value (Y or N)? ');
      ReadLn(key_entered);
      until ((key_entered = 'N') or (key_entered = 'n'));
      ClrScr;
end. (* main *)