/****************************************************************************
 *                        C SAMPLE #1: SAMPLE1.C                            *
 *                                                                          *
 *  This sample will prompt the user for a voltage between 0 and 10 volts,  *
 *  then calculate the actual voltage based on the resulution 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.                   *
 *                                                                          *
 ****************************************************************************/
#include <stdio.h>
#include <dos.h>
#include <conio.h>

unsigned AskForBaseAddress(unsigned int OldOne)
{
	char msg[7];
	int NewOne = 0, Success = 0, Dummy;
	int AddrInputPosX, AddrInputPosY;

	puts("\nPlease enter the Base Address for your card (in hex)");
	printf("or press ENTER for %X.\n>", OldOne);
	AddrInputPosX = wherex(); AddrInputPosY = wherey();
	do {
      gotoxy(AddrInputPosX, AddrInputPosY);
      clreol();
      msg[0] = 5; msg[1] = 0;
      cgets(msg);
      sscanf(msg + 2, "%x", &NewOne);
      Success = 1;
      Dummy = NewOne;
		if (msg[1] == 0) {
        gotoxy(AddrInputPosX, AddrInputPosY);
        printf("%X", OldOne);
        Success = 1;
        Dummy = OldOne;
      }
	} while(!Success);
	return (Dummy);
} /* 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.                              *
 ****************************************************************************/
void write_DAC(unsigned int Address)
{
   float           volt_value_entered,volt_value_expected;
   unsigned        counts_entered,temp,dac_number;
   unsigned char   lo_byte,hi_byte;
   char            ch;

   /* prompt for the DAC number and desire voltage. */

   do {
      gotoxy (1,2);
      clreol();
      printf("Enter the DAC number you wish to output to (0 or 1 only): ");
      ch=getche();
      dac_number=ch-'0';         /* using ascii code to get dac_number */
   } while (((int)dac_number < 0) || ((int)dac_number > 1));
   do {
   gotoxy (1,7);
   clreol();
   printf("Enter a voltage between 0.000v to 9.997v: ");
   scanf("%f",&volt_value_entered);
   } while ((volt_value_entered<0.000) || (volt_value_entered>9.997));
   volt_value_entered /= 0.002441;

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

   counts_entered=(int) volt_value_entered;
   volt_value_expected = (float) counts_entered * 0.002441;
   printf("\n\n\nDue to the 12-bit resolution of the DAC, you should expect\n");
   printf("to see a voltage of %4.3f.",volt_value_expected);

   /* prepare the control word and write to the DAC */

   temp = counts_entered;
   counts_entered /= 256;                       /* extract hi byte            */
   hi_byte = (unsigned char) counts_entered;    /* convert to character       */
   temp %= 256;                                 /* extract low byte           */
   lo_byte = (unsigned char) temp;              /* convert to character       */
   outportb(Address+0x08+(2 * dac_number),lo_byte); /* write low byte         */
   outportb(Address+0x08+(2*dac_number+1),hi_byte); /* write high byte        */
} /* end write_DAC */

/****************************************************************************
 *                                                                          *
 *  FUNCTION: main() - local routine                                        *
 *                                                                          *
 ****************************************************************************/
void main()
{
   int     key_entered;
   unsigned int Address;

   clrscr();
   printf(
    "                        C SAMPLE #1: SAMPLE1.C                            \n"
    "                                                                          \n"
    "  This sample will prompt the user for a voltage between 0 and 10 volts,  \n"
    "  then calculate the actual voltage based on the resolution of the DAC and\n"
    "  output the voltage to the desired DAC channel.                          \n"
    "                                                                          \n");
   Address=AskForBaseAddress(0x340);
   clrscr();
   outportb(Address+0x08,0);    /* set DAC to 0 output */
   outportb(Address+0x09,0);
   outportb(Address+0x0a,0);    /* set DAC to 0 output */
   outportb(Address+0x0b,0);
   printf(
    "\n\n\n  Board Configuration:                     \n\n"
    "  -- Base address is %x hex.                       \n"
    "  -- DACs must be placed in the 10V unipolar mode. \n"
    "  -- The 2's complement jumper must be removed.    \n"
    "\n\n\n\nPress any key to continue", Address);
    getch();

   do
      {
      clrscr();
      write_DAC(Address);
      printf("\n\n\nWould you like to output another value (Y or N)? ");
      key_entered = getch();
      }
   while((key_entered != 'N') && (key_entered != 'n'));
   clrscr();
} /* end main */