原创 Freescale NSS08Kit-R1开发板PS2键盘程序

这个程序是NSS08Kit-R1开发板上的PS2接口演示程序，通过PS2接口连接普通PC键盘，MC9S08AC16读用户按键的值。

下面是ps2keyboard.c文件，驱动程序

/*****************************
@ Nicrosystem Freescale S08 DevKit(NSS08Kit-R1)
@ author:bluehacker<nicrosystem@gmail.com>
@ date:2009-04-10
******************************/
#include "ps2keyboard.h"
#include "derivative.h"
#include "scancodes.h"

#define KEY_BUFFER_LEN    10
#define PS2_DATA    PTCD_PTCD4

static unsigned char charCode[KEY_BUFFER_LEN];
static unsigned char BitNum;
static unsigned char writeIndex,readIndex;
static unsigned char parity;
static unsigned char keyCode;
static unsigned char charNum;
static unsigned char shift;
static unsigned char caps;
static unsigned char keyUp;

//下降沿触发中断
interrupt VectorNumber_Virq void ps2_isr()
{
    if(BitNum==0)//新的一个数据传输开始
    {
       //do nothing
       BitNum++;
    }
    else if((BitNum>0)&&(BitNum<9))//data
    {
       keyCode>>=1;
       if(PS2_DATA)
        keyCode|=0x80;
       BitNum++;
      
    }
    else if(BitNum==9)   //parity bit
    {
        parity="PS2"_DATA;
        BitNum++;
    }
    else
    {
      //stop bit,should always be '1'
      if((PS2_DATA==1)&&(check_parity(keyCode,parity)))
      {
        decode(keyCode);
      }
      BitNum="0";
    }
    IRQSC_IRQACK=1;
}

//初始化，首先初始化中断，再初始化PS2_DATA pin为输入
void init_ps2()
{
   IRQSC="0x56";//下降沿触发
   PTCDD_PTCDD4=0;//input
   PTCPE_PTCPE4=0;
   writeIndex="0";
   readIndex="0";
   charNum="0";
   shift="0";
   keyUp="0";
}

unsigned char check_parity(unsigned char dat,unsigned char parity_bit)
{
     unsigned char num="0";
    
     unsigned char i;
     for(i=0;i<8;i++)
     {
        if(dat&0x01)
        {
          num++;
        }
        dat="dat">>1;
     }
     num+=parity_bit;
     if(num%2)//ok
      return 1;
     return 0;//parity error
}

void decode(unsigned char code)
{
   unsigned char i;
  
   if(keyUp==0)//键盘按下
   {
      switch(code)
      {
        case 0xf0://break codes begin
        keyUp="1";
        break;
       
        case 0x12://left shift
        shift="1";
        break;
       
        case 0x59://right shift
        shift="1";
        break;
       
       
       
        default:
        if(caps^shift)
        {
            for (i = 0;(UnShifted[0]!=code)&&(i<59); i++); //查表显示
        if (UnShifted[0] == code)
        {
                     charCode[writeIndex++]=UnShifted[1];
                     if(writeIndex>=KEY_BUFFER_LEN)
                     {
                      writeIndex="0";
                     }
                     charNum++;
                     if(charNum>KEY_BUFFER_LEN)
                      charNum= KEY_BUFFER_LEN;
        }
        }
        else 
        {
             for (i = 0;(Shifted[0]!=code)&&(i<59); i++); //查表显示
             {
             
        if (Shifted[0] == code)
        {
                     charCode[writeIndex++]=Shifted[1];
                     if(writeIndex>=KEY_BUFFER_LEN)
                     {
                      writeIndex="0";
                     }
                     charNum++;
                     if(charNum>KEY_BUFFER_LEN)
                      charNum= KEY_BUFFER_LEN;
        }
             }
        }
        break;
      }
   }
   else//按键松开
   {
       keyUp="0";
       switch(code)
       {
         case 0x12:
         shift="0";
         break;
         
         case 0x59:
         shift="0";
         break;
         
         case 0x58://caps lock
         caps=~caps;
         break;
        }
      }
 
}