keyboard.c

一个在51单片机下PS/2键盘的应用

/*www.wzlab.com
 *ps2键盘驱动
 *使用终端读数据
 *
 */
#include "keyboard.h"
#include "scancodes.h"

#define PIN_DIR DDRD
#define PIN_KB  PIND
#define PORT_KB PORTD
#define CLOCK   3
#define DATAPIN 2

#define BUFF_SIZE 32

unsigned char bitcount;  
unsigned char kb_buffer[BUFF_SIZE];
volatile unsigned char kinput=0;
unsigned char koutput=0;

void put_kbbuff(unsigned char c)
{
    kb_buffer[kinput]=c;
    if (kinput<(BUFF_SIZE-1))
	kinput++; 
    else
	kinput=0;	 
}

int keyboard_getchar(void)
{
    unsigned char temp;
    if(koutput==kinput){
	return 0;
    }
    else{
	temp=kb_buffer[koutput];
	koutput=(koutput<(BUFF_SIZE-1))?(koutput+1):0;
	return temp;	  
    }	     
}


void keyboard_init(void)
{
    PIN_DIR&=~((1<<CLOCK)|(1<<DATAPIN));
    PORT_KB|=(1<<CLOCK)|(1<<DATAPIN);
    MCUCR = 0x08; 	
    GICR  = 0x80;
    sei();
    bitcount = 11;

}

/*		查表解码		*/
void decode(unsigned char sc)
{
    static unsigned char shift,up,shiftup;
    
    unsigned char i;
    
    if(sc==0xf0)
		{
	    	up=1;
	    	return;
		}
		
    if(up==1)
		{
	    	up=0;
	    	if ((sc==0x12)|(sc==0x59)) shift=0;
	    	return;
		}	
		 
    switch (sc)
		{
				case 0x12:
	    						shift  =1;		
	    						shiftup=1;
           
				case 0x59:
	    						shift  =1;	
	    						shiftup=1;
           
				default:
	    						if (shift==0)
									{
		    							for(i = 0;(pgm_read_byte(unshifted+2*i)!=sc) && pgm_read_byte(unshifted+2*i); i++);
		    							if (pgm_read_byte(unshifted+2*i) == sc)
		    							{
													put_kbbuff(pgm_read_byte(unshifted+i*2+1));
		    							}
									}
	    						else
									{
		    							for(i = 0;(pgm_read_byte(shifted+2*i)!=sc) && pgm_read_byte(shifted+2*i); i++);
		    							if (pgm_read_byte(shifted+2*i) == sc)
											{
			    								put_kbbuff(pgm_read_byte(shifted+2*i+1));						  
											}	 	 						 
									} 	         
		} 		
}

SIGNAL(SIG_INTERRUPT1)
{
    static unsigned char data;   	
    
    switch (bitcount)
	  {
			case 11:
	    				if ((PIN_KB&(1<<DATAPIN))!=0) return;
							
	    				else		  bitcount--;
							
	   					break;
	   					
			case 2:
	    				bitcount--;	   		   
	    				break;

			case 1:				
	    				bitcount--;	 
	    				
	    				if((PIN_KB&(1<<DATAPIN))==0)
							{
		   						 bitcount=11;
		    					 return;
							}
	   				  else
							{
		    					 bitcount=11;
		    					 decode(data);
							}	  
	    				break;
	    				
		 default:
	    			 data = (data >> 1);
	    			 
	    			 if((PIN_KB&(1<<DATAPIN))!=0)
						 data|=0x80;
						 
	    			 bitcount--;		
	  }
			 		 	  	
}