keypad.c

《OSEK/VDX汽车电子嵌入式软件编程技术》中光盘的资料

/************************************************
*
*	$Copyright    2001 Joseph J. Lemieux  ALL RIGHTS RESERVED. $
*
*	$Filename: C:\OSEKBook\src\CH05\src\keypad.c $
*
*	Description: Keypad Sample and Control Routines	
*
************************************************/
#ifndef KEYPADC
#define KEYPADC

/************************************************
*
*	Include files
*
************************************************/

#include "typedefs.h"
#include "os.h"
#include "keypad.h"
#include "hw.h"

DeclareTask(ProcessKeyPress);

/************************************************
*
*	Local macros
*
************************************************/

/************************************************
*
*	Local type definitions
*
************************************************/

/************************************************
*
*	Local Function Prototypes
*
************************************************/

/************************************************
*
*	Local Variables
*
************************************************/

/************************************************
*
*	Global Variables
*
************************************************/
/***
*
* Value of Last Key Pressed and debounce timer
*
***/
char keyValue;
UINT8 keyCount=0;
char lastKey = 0;

/************************************************
*
*	Local Constants
*
************************************************/

/************************************************
*
*	Functions
*
************************************************/
/************************************************
*
*   Task:         IOSampleKeypad
*
*   Description:  Samples the keypad and debounces
*                 any keypresses.
*
************************************************/
TASK(IOSampleKeypad)
{
static BOOLEAN keyState = FALSE;
char tempKey;

   tempKey = HWGetValue(&KEYPAD);
   if(tempKey == lastKey){
      if(keyCount++ == KEY_DEBOUNCE_TIME){
            --keyCount;
            keyValue = tempKey;
      }
   }
   else{
         keyCount = 0;
         lastKey = tempKey;
   }
   if(keyState==FALSE){
      if(keyValue != 0){
            keyState = TRUE;
            ActivateTask(ProcessKeyPress);
      }
   }
   else{
      if(keyValue == 0){
            keyState = FALSE;
      }
   }
   TerminateTask();
}
#endif /* KEYPADC */