Input Programming

1. port + 0
  MSN


                                                   


LSB
7
 6
 5
 4
 3
 2
 1
 0
Input A/D low byte data.
2. port + 1
 MSN




                                                 
LSB
0
0
0
0
11
 10
  9
 		 8
Input A/D high byte data.
3. port + 2
MSN





LSB
/hold
 R2
 R1
 R0
 C3
 C2
 C1
  C0 
Read back control signal for data conversion. Please refer next section for more details.
4. port +4
MSN





LSB
1D7
 1D6
 1D5
 1D4
 1D3
 1D2
 1D1
 1D0
Digital input channel 1.

5. port + 5
MSN





LSB
2D7
 2D6
 2D5
 2D4
 2D3
 2D2
 2D1
 2D0
Digital input channel 2.

6. port + 6
MSN





LSB
3D7
 3D6
 3D5
 3D4
 3D3
 3D2
 3D1
 3D0
Digital input channel 3.
7. port + 7
MSN





LSB
4D7
 4D6
 4D5
 4D4
 4D3
 4D2
 4D1
 4D0
Digital input channel 4.

8. port + 8
Counter 0 I/O buffer (8254 IC).

 9. port + 9
Counter 1 I/O buffer (8254 IC).

10. port + A
Counter 2 I/O buffer (8254 IC).

11. port + B
Counter control register (8254 IC).

Output Programming
1. port + 0
MSN





LSB
x
 R2
 R1
 R0
 C3
 C2
 C1
 C0
Select A/D channel number and enable/disable the selected channel. The R0 to R2 are used to select gain control factor, and the C0 to C4 are used to select A/D input channel. If JP5 is short, the Ro to R2 are disable.
R2 R1 R0 Gain Control Factor
0 0 0 *1
0 0 1 *2
0 1 0 *3
0 1 1 *4
1 0 0 *5
1 0 1 *6
1 1 0 *7
1 1 1 *8
The gain control factor is used to scale your input voltage. For example, if you select unipolar and its voltage range from 0 to 20V, and the gain control factor is *8, then your input voltage range is from 0 to 2.5V, because whole the input voltage was scale 8 times.
C3 C2 C1 C0 Input Channel
0 0 0 0 CH0
0 0 0 1 CH1
0 0 1 0 CH2
0 0 1 1 CH3
0 1 0 0 CH4
0 1 0 1 CH5
0 1 1 0 CH6
0 1 1 1 CH7
1 0 0 0 CH8
1 0 0 1 CH9
1 0 1 0 CH10
1 0 1 1 CH11
1 1 0 0 CH12
1 1 0 1 CH13
1 1 1 0 CH14
1 1 1 1 CH15
2. port + 1
MSN





LSB
ENX
 		X
 		T1
 		T0
 		SL3
 		SL2
 		SL1
 		SL0
Select IRQ and select control method. The T1 and T2 are used to select trig method for A/D converter, and the SL0 to SL3 are used to select interrupt line. When user select external trig(T1=1 and T0=0), he must connect J3 pin 2.
ENX Enable/Disable
0 Gate Disable
1 Gate Enable
T1 T0 Selection
0 0 Software trigger by port address + 2
0 1 Trig by 8254
1 0 External trig from J3-2
1 1 No trigger
When user select trig by 8254 (T1=0 and T0 =1), he must enable the gate by set ENX bit. The clock rate of 8254 is 2M, it is connected to counter 0, then the output of counter 0 is connected to counter 1, so that user need divide the clock by counter 0 then divide it by counter 1. The divided clock rate of counter 1 is used to trig A/D conversion.
SL3 SL2 SL1 SL0 Interrupt Selection
0 x x x No selection
1 0 0 0 IRQ3
1 0 0 1 IRQ4
1 0 1 1 IRQ5
1 0 1 1 IRQ7
1 1 0 0 IRQ10
1 1 0 1 IRQ11
1 1 1 0 IRQ12
1 1 1 1 IRQ15
3. port + 2
Start data conversion. When you select the software trigger (T1=0, T0=0) to start the A/D converter process, you can write any value to this address and start A/D converter process. It needs about 200ns to convert the signal.
4. port + 3
Output signal to reset/retrigger IRQ. When the A/D chip finish the converter process, they generate interrupt request selected by your choice channel. After your program finish the job, you must write any value to this address to clear the interrupt request signal.
5. port + 4
MSN





LSB
1D7
 1D6
 1D5
 1D4
 1D3
 1D2
 1D1
 1D0
Digital output channel 1.

6. port + 5
MSN





LSB
2D7
 2D6
 2D5
 2D4
 2D3
 2D2
 2D1
 2D0
Digital output channel 2.

7. port + 6
MSN





LSB
3D7
 3D6
 3D5
 3D4
 3D3
 3D2
 3D1
 3D0

8. port + 7
MSN





LSB
4D7
 4D6
 4D5
 4D4
 4D3
 4D2
 4D1
 4D0

9. port + 8
   counter 0 I/O buffer (8254 IC).

 10. port + 9
   counter 1 I/O buffer (8254 IC).

11. port + A
   counter 2 I/O buffer (8254 IC).

12. port + B
   counter control register (8254 IC).
Programming Examples
If you want port+4, port+5, port+6, and port+7 as input channel, you must write FFH value to this port. In the following, we show a C language example.

This program uses the minimum resources of the 12 bit data acq uisition.  It only uses IRQ5 and an analog channel and checks digital channels in the card, but before you can use the option for digital I/O you must have a 2 x 26 pin cable connector placed in J1 and J2.
#include <stdio.h>#include <conio.h>#include <dos.h>#include <ctype.h>#include <process.h>#include <stdlib.h>
#ifdef __cplusplus    #define __CPPARGS ...#else    #define __CPPARGS#endif
int channel = 0, address = 0x200;
unsigned int hibyte, lobyte;
float ad;
long int countint;

void main();

void interrupt (*old_interrupt)(__CPPARGS);    //interrupt handler

void interrupt dataacq_interrupt(__CPPARGS)  //interrupt service routine
{
countint++;  //interrupt counter
outportb(address, channel);  //selects the channel that will send a signal
outportb(address + 3, 0x00);  //resets the IRQ
hibyte = inportb(address + 1); //captures hibyte data
lobyte = inportb(address);  //captures lobyte data
outportb(0x20, 0x20); //end of interrupt
}


void one_channel()
{
int looping, OldMask1, NewMask1;
char select_irq, get_ch;

countint = 0;
clrscr();
old_interrupt = getvect(0x0d);       //save old interrupt service routine
disable();                         //disable interrupts
setvect(0x0d, dataacq_interrupt);  //use new ISR
enable();                    //enable interrupts
OldMask1 = inportb(0x21);              //save old interrupt mask
NewMask1 = OldMask1 & 0xDF;       //0xDF masks the interrupt to be used
outportb(0x21, NewMask1);         //output new interrupt mask

//controls output of counter to 100hz
outportb(address + 11, 0x36);
outportb(address + 8, 0xff);
outportb(address + 8, 0x03);
outportb(address + 11, 0x76);
outportb(address + 9, 0x14);
outportb(address + 9, 0x00);

clrscr();
gotoxy(21,3);printf("Channel             Received Value");
gotoxy(20,22);printf("Press 'Space' To Pause and Any Key To Quit");
outportb(address + 1, 0x9A); // output to selected irq
outportb(address + 3, 0x00);  //reset IRQ

do
    {
    gotoxy(1,1);printf("Interrupt Count: %ld", countint); //loop counter

    while(kbhit())//if key is pressed
        {
        get_ch = toupper(getch());
        if(get_ch == 0x20)  //if space bar
            {
            getch();
            }
        else
            {
            disable(); //disable interrupt
            setvect(0x0d, old_interrupt);  //restore old ISR
            enable(); //enable interrupt
            outportb(0x21, OldMask1);   //restore old mask
            main();
            }
        }
ad = ((hibyte & 0x0f) << 8) + (lobyte & 0xff);  //convert  hex   value to decimal
    ad = (ad * 10) / 0xfff;

    for(int z=0;z<=50;z++)     //loop counter
    for(int y=0;y<=100;y++)

    gotoxy(24,5);printf("%d", channel);  //display channel
    gotoxy(45, 5);printf("%.3f ", ad);  //display data
       
}
while(!kbhit());
disable();
setvect(0x0d, old_interrupt);
enable();
outportb(0x21, OldMask1);
main();
}


void digital_io()
{
int four_digital_io, all_hi, digital_addr, count_by_5, digital_send;
int data_read;
long int loop_count = 0;
char esc_key;

do
    {
    clrscr();
    gotoxy(28,20);printf("Press Any Key To Quit");
    gotoxy(1,1);printf("Loops: %ld    ", loop_count);

    for(count_by_5 = 0; count_by_5 <= 255; count_by_5 +=5)
        {
        delay(5);
        while(kbhit())
            {
            main();
            }
        gotoxy(1,4);printf("Transfer Data J3-1D to J2-3D");
        outportb(address + 4, count_by_5);
        outportb(address + 6, 0xff);
        data_read = inportb(address + 6);
        gotoxy(1,5);printf("Digital Input = %d   ",data_read);
        if(count_by_5 == data_read)
            {
            gotoxy(25,5);printf("...Pass  ");
            }
        else
            {
            gotoxy(25,5);printf("...Error");
            gotoxy(25,20);printf("Press Any Key To Continue");
            esc_key = getch();
            if(esc_key == 0x1b)
                {
                main();
                }
            }
        }
    loop_count++;
    }
while(!kbhit());
}

void main()
{
char main_select;

clrscr();

//main menu
gotoxy(25,7);printf("12 BIT DATA ACQUISITION CARD");
gotoxy(28,9);printf("[1] Test Analog Input");
gotoxy(28,10);printf("[2] Digital I/O");
gotoxy(28,11);printf("[3] Exit");
gotoxy(30,13);printf("Choose Option: ");

do
    {
    gotoxy(45,13);main_select = toupper(getch());
    switch(main_select)
        {
        case '1':
            //menu select for analog input function
            one_channel();
            break;
        case '2':
            digital_io();
            break;
        case '3':
//Terminates the program whenever the user chooses 5 from the main menu
            exit(0);
            break;
        }
    }
while(1);
 }