led_flash.c

keil C51 Portable事例

/*------------------------------------------------------------------*-

   LED_flash.C (v1.00)

  ------------------------------------------------------------------
   
   Simple 'Flash LED' test function.

   COPYRIGHT
   ---------

   This code is associated with the book:

   EMBEDDED C by Michael J. Pont 
   [Pearson Education, 2002: ISBN: 0-201-79523-X].

   This code is copyright (c) 2001 by Michael J. Pont.
 
   See book for copyright details and other information.

-*------------------------------------------------------------------*/

#include "Main.H"
#include "Port.H"

#include "LED_flash.H"

// ------ Private variable definitions -----------------------------

static bit LED_state_G;

/*------------------------------------------------------------------*-

  LED_FLASH_Init()

  Prepare for LED_Change_State() function - see below.

-*------------------------------------------------------------------*/
void LED_FLASH_Init(void)
   {
   LED_state_G = 0;
   }


/*------------------------------------------------------------------*-

  LED_FLASH_Change_State()

  Changes the state of an LED (or pulses a buzzer, etc) on a 
  specified port pin.

  Must call at twice the required flash rate: thus, for 1 Hz
  flash (on for 0.5 seconds, off for 0.5 seconds) must call
  every 0.5 seconds.

-*------------------------------------------------------------------*/
void LED_FLASH_Change_State(void)
   {
   // Change the LED from OFF to ON (or vice versa)
   if (LED_state_G == 1)
      {
      LED_state_G = 0;
      LED_pin = 0;
      }
   else
      {
      LED_state_G = 1;
      LED_pin = 1;
      }
   }

/*------------------------------------------------------------------*-
  ---- END OF FILE -------------------------------------------------
-*------------------------------------------------------------------*/