keyproc.c

msp430液晶显示

#include "chip.h"
#include "pcf8574.h"
#include "i2c.h"
#include "key.h"
 const unsigned char KEY_ROW[]={KEY_ROW1,KEY_ROW2,KEY_ROW3}; //scan status code
 const unsigned char KEY_VALUE[][2]={
                                     {0xD8,'1'},{0xD4,'2'},{0xCC,'3'},
				     {0xB8,'4'},{0xB4,'5'},{0xAC,'6'},
				     {0x78,'7'},{0x74,'8'},{0x6C,'9'}};
				     
void InitKeyPort(void)
{
  P1SEL &=~BIT4;     //P1.4 input direction
  P1DIR &=~BIT4;
  P1IES |=BIT4;      //P1.4 falling edge interrupt
  P1IE  |=BIT4;      //enable P1.4 interrupt(external interrupt 4)
}

void KeyDebounce(unsigned int i)
{
  while(i--);
}

unsigned char KeyProcess(void)
{
 unsigned char Key,i,keycnt;
 for(i=0;i<3;i++)
 {  
  I2CWrByte(I2CWR_ADDR,KEY_ROW[i]);  //writting row code to identify the location pressed key
  I2CRdByte(I2CRD_ADDR,&Key);        //read into the location code in row
  KeyDebounce(KEY_DEBOUNCE_TIME>>1);  //debounce
  if((Key & NO_KEY)!=NO_KEY)         //key has pressed
  {
    KeyDebounce(KEY_DEBOUNCE_TIME);  //debounce
    I2CRdByte(I2CRD_ADDR,&Key);        //read into the location code in row
    if((Key & NO_KEY)!=NO_KEY)       //if has key
    {
     Key &=MASK_LED;
     for(keycnt=0;keycnt<9;keycnt++) //conversion scan value to character
     {
       if(Key==KEY_VALUE[keycnt][0]){ Key=KEY_VALUE[keycnt][1];keycnt=10;} //lookup tabe
     }
     I2CWrByte(I2CWR_ADDR,KEY_INIT_LED1 );//restoration key status and LED dead
     return Key;                      //return key value 
    }
    else                             //no key
    {
     I2CWrByte(I2CWR_ADDR,KEY_INIT_LED1); //restoration key status and LED lighting
     return NO_KEY;                       //return null value of key
    }
   }
 }  
 I2CWrByte(I2CWR_ADDR,KEY_INIT_LED1);     //restoration key status and LED lighting
 return NO_KEY;                           //return null value of key
}