Bu driver ile devrede ps/2 klayeden gönderilen bilgiler çözülerek istenilen amaç için kullanıma uygun hale getirilir. Gelen bilgiyi çözme iÅŸi kesmeler sayesinde yapıldığından gereksiz ere “tuÅŸa basıldı mı?” kontrollerine gerek kalmaz.Programda keyhit() fonksiyonu ile erhangi bir tuÅŸa basılıp basılmadığı anlaşılır, waitKey() ilede basılan tuÅŸun ne olduÄŸu
belirlenir.

Pin diyagramı:

Kaynak kodu:

//Writer stevenm86
#include <16f628>
#fuses HS,NOWDT,NOPROTECT,NOLVP,NOBROWNOUT,NOPUT
#use delay(clock=4096000)
#include “flexy_lcd.c”

//D0 - Clock
//D1 - Data

// Clock must be the interrupt pin
#define CLOCK PIN_B0
#define DATA  PIN_D3

unsigned char bData[16];
unsigned char idx=0;
unsigned char tmp=0;

unsigned char readByte();
unsigned char processByte();
unsigned char waitKey();
byte keyhit();
unsigned char translate(unsigned char scancode);

volatile byte shiftSet = 0;

byte kbBuffer[16];
byte kbPos = 0;
byte kbSize = 0;
byte capsSet = 0;
volatile byte extFlag = 0;
volatile byte relFlag = 0;
volatile byte key=0;

void sendByte(byte b)
{
    byte a=0;
    byte p = 1;
    byte t = 0;

    return;         

    disable_interrupts(GLOBAL);
    output_low(CLOCK);
    delay_us(300);
    output_low(DATA);
    input(CLOCK);

    for(a=0; a<8; a++)
    {
        t = b&(1<
        while(input(CLOCK) == 1); //wait for 0
        output_bit(DATA, t);
        if(t)
            p++;
        while(input(CLOCK) == 0); //wait for 1
    }

    while(input(CLOCK) == 1); //wait for 0
    output_bit(DATA, p&0×01);
    while(input(CLOCK) == 0); //wait for 1

    input(DATA);
    while(input(DATA) == 1); //wait for 0
    while(input(CLOCK) == 1); //wait for 0

    delay_ms(10);

    clear_interrupt(INT_EXT);
    enable_interrupts(GLOBAL);
}

main()
{
    int i=0;
    unsigned char k=0;
    printf(lcd_putc “READY >”);

    output_b(0×00);
    input(CLOCK);

    delay_ms(100);

    ext_int_edge(H_to_L);
    enable_interrupts(INT_EXT);
    enable_interrupts(GLOBAL);

    while(1)
    {
        k = waitKey();
        printf(lcd_putc,”%c”, k);

        while(keyhit())
            printf(lcd_putc,”%c”, waitKey());
    }
}

byte keyhit()
{
    return kbSize != 0;
}

unsigned char waitKey()
{
    unsigned char k = 0;
    while(kbSize == 0);
    k = kbBuffer[(kbPos - kbSize)&0×0F];
    kbSize–;
    return k;
}

#int_ext
void kbInterrupt()
{
    volatile byte k=0;
    k = processByte();

    if(k != 0)
    {
        kbBuffer[kbPos] = k;
        kbPos = ++kbPos & 0×0F;
        kbSize++;
    }
    return;
}

unsigned char readByte()
{
    int i=0, t=0;
    idx=0;
    tmp=0;

    i=0;
    goto dataread;
   // while(INPUT(CLOCK) != 0);   // Wait for a keypress
            t=0;
       while(INPUT(CLOCK) != 0 && t<255)   // Wait for clock, time out if needed
       {
           delay_us(1);
           t++;
       }
    for(i=0; i<11; i++)
    {
        t=0;
        while(INPUT(CLOCK) != 0 && t<255)   // Wait for clock, time out if needed
        {
            delay_us(1);
            t++;
        }
        dataread:

        bData[idx]=INPUT(DATA);
        idx++;
        if(idx==9)
        {
            for(idx=1; idx<9; idx++)
                if(bData[idx]!=0)
                    tmp|=(1<<(idx-1));

            return tmp;
            idx=0;
            tmp=0;
        }
     //   while(INPUT(CLOCK) == 0);
        t=0;
        while(INPUT(CLOCK) == 0 && t<255)   // Wait for clock, time out if needed
        {
            delay_us(1);
            t++;
        }

    }
}

static const unsigned char scantableAZ[]={
0x1C, 0x32, 0x21, 0x23, 0x24, 0x2B, 0x34, 0x33, 0x43, 0x3B, 0x42, 0x4B, 0x3A, // A-Z
0x31, 0x44, 0x4D, 0x15, 0x2D, 0x1B, 0x2C, 0x3C, 0x2A, 0x1D, 0x22, 0x35, 0x1A};

// Normal numeric scancodes, starting with ',' .
static const unsigned char scantable09n[]=
{
0x41, 0x4E, 0x49, 0x4A, // , - . /
0x45, 0x16, 0x1E, 0x26, 0x25, 0x2E, 0x36, 0x3D, 0x3E, 0x46,     //Digits 0-9
0x00, 0x4C, 0x00, 0x55 // 0 ; 0 =
};

// Shift scancodes, starting at '!'
static const unsigned char scantable09s[]=
{
    0x16, 0x52, 0x26, 0x25, 0x2E, 0x3D, 0x00, 0x46, 0x45, 0x3E, 0x55
};

// Normal misc. scancode map. Scancode, ASCII value
static const unsigned char scanmapn[]=
{0x54, '[', 0x5B, ']', 0x0E, '`', 0x5D, '\\', 0x52, '\''};

// Shifted misc. scancode map. Scancode, ASCII value
static const unsigned char scanmaps[]=
{0x1E, '@', 0x36, '^', 0x4E, '_', 0x54, '{', 0x5B, '}', 0x5D, '|',
0x4C, ':', 0x41, '<', 0x49, '>‘, 0×4A, ‘?’, 0×0E, ‘~’};

// Scancode map independent of Shift
static const unsigned char scanmapx[]=
{0×29, ‘ ‘, 0×5A, ‘\r’, 0×0D, ‘\t’, 0×76, 27, 0×66, 0×08};

// Extended scancode map
static const unsigned char scanmape[]=
{
0×71, 0×7F
};

unsigned char translate(unsigned char scancode)
{
    int i=0;

    if(extFlag == 0)
    {
        for(i=0; i<10; i+=2)
            if(scanmapx[i] == scancode)
                return scanmapx[i+1];

        for(i=0; i<26; i++)
            if(scantableAZ[i] == scancode)
                if(shiftSet ^ capsSet)
                    return i+65;
                else
                    return i+65 + 32;

        if(shiftSet)
        {
            for(i=0; i<11; i++)
                if(scantable09s[i] == scancode)
                    return i+'!';

            for(i=0; i<22; i+=2)
                if(scanmaps[i] == scancode)
                    return scanmaps[i+1];
        } else
        {
            for(i=0; i<18; i++)
                if(scantable09n[i] == scancode)
                    return i+',';

            for(i=0; i<10; i+=2)
                if(scanmapn[i] == scancode)
                    return scanmapn[i+1];
        }
    } else      // Extended keys
    {
        for(i=0; i<2; i+=2)
            if(scanmape[i] == scancode)
                return scanmape[i+1];
    }
    return '?';
}

unsigned char processByte()
{
    unsigned char i, j;
    i = readByte();

    if(i == 0xF0)       //A key is being released
    {
        relFlag = 1;
        return 0;
    }

    if(i == 0xE0)       // Extended key operation
    {
        extFlag = 1;
        relFlag = 0;    //0xE0 always first in sequence, OK to clear this
        return 0;
    }

    if(relFlag == 0)    // Pressing a key
    {
        if(extFlag == 0)    // Non-extended key pressed
        {
            if(i == 0x12 || i == 0x59)
            {
                shiftSet = 1;
                return 0;
            }

            if(i == 0x58)
            {
                sendByte(0xED);
                if(capsSet == 0)
                {
                    capsSet = 1;
                    sendByte(0x04);
                } else
                {
                    capsSet = 0;
                    sendByte(0x00);
                }
                return 0;
            }

        }
        j = translate(i);
        extFlag = 0;
        return j;
    }

    if(relFlag == 1)    //Releasing a key
    {  //If a flag was set but not handled, we wouldn’t have gotten here

        relFlag = 0;
        extFlag = 0;    //OK to clear this here

        if(extFlag == 0)   // Releasing a nonextended key
        {
            if(i == 0×12 || i == 0×59)
            {
                shiftSet = 0;
                return 0;
            }

        }
    return 0;
}

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