led_mx4.c

自己做的时钟

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

   LED_Mx4.C (v1.00)

  ------------------------------------------------------------------

   Simple library function for displaying data on four multiplexed,
   eight-segment LED displays


   COPYRIGHT
   ---------

   This code is from the book:

   PATTERNS FOR TIME-TRIGGERED EMBEDDED SYSTEMS by Michael J. Pont 
   [Pearson Education, 2001; ISBN: 0-201-33138-1].

   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_Mx4.h"

// ------ Public variable definitions ------------------------------

// Lookup table - stored in code area
// See Port.H for connections and code details

tByte code LED_Table_G[20] = 
// 0     1     2     3     4     5     6     7     8     9
{0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07, 0x7F, 0x6F,
// 0.    1.    2.    3.    4.    5.    6.    7.    8.    9.
 0xBF, 0x86, 0xDB, 0xCF, 0xE6, 0xED, 0xFD, 0x87, 0xFF, 0xEF};

// Global data formatted for display (initially 0,0,0,0)
tByte LED_Mx4_Data_G[4] = {0x3F,0x3F,0x3F,0x3F};


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

static tByte Digit_G;

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

  LED_MX4_Display_Update()

  Updates (four) multiplexed 8-segment LED displays.

  Usually aim to scheduled at around 3ms intervals: typically
  around a 1% CPU load on standard 8051.  

-*------------------------------------------------------------------*/
void LED_MX4_Display_Update(void)
   {
   
   // Increment the digit to be displayed
   if (++Digit_G == LED_NUM_DIGITS)
      {
      Digit_G = 0;
      }

   // Allows any pins to be used
   switch (Digit_G)
      {
      case 0:
         {      
         LED_DIGIT_0 = 0;
         LED_DIGIT_1 = 0;
         LED_DIGIT_2 = 0;
         LED_DIGIT_3 = 1;
         break;
         }

      case 1:
         {      
         LED_DIGIT_0 = 0;
         LED_DIGIT_1 = 0;
         LED_DIGIT_2 = 1;
         LED_DIGIT_3 = 0;
         break;
         }

      case 2:
         {      
         LED_DIGIT_0 = 0;
         LED_DIGIT_1 = 1;
         LED_DIGIT_2 = 0;
         LED_DIGIT_3 = 0;
         break;
         }

      case 3:
         {      
         LED_DIGIT_0 = 1;
         LED_DIGIT_1 = 0;
         LED_DIGIT_2 = 0;
         LED_DIGIT_3 = 0;
         }
      }

   LED_DATA_PORT = 255 - LED_Mx4_Data_G[Digit_G];
   }

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