C51 COMPILER V7.06   SWITCH_WAIT_TIMEOUTL                                                  12/16/2004 10:23:59 PAGE 1   


C51 COMPILER V7.06, COMPILATION OF MODULE SWITCH_WAIT_TIMEOUTL
OBJECT MODULE PLACED IN Switch_Wait_TimeoutL.OBJ
COMPILER INVOKED BY: d:\Keil\C51\BIN\C51.EXE Switch_Wait_TimeoutL.c OPTIMIZE(6,SPEED) BROWSE DEBUG OBJECTEXTEND

stmt level    source

   1          /*------------------------------------------------------------------*-
   2          
   3             Switch_Wait_TimeoutL.C (v1.00)
   4          
   5            ------------------------------------------------------------------
   6          
   7             Simple library for processing a switch input.
   8          
   9             (Made more reliable by means of a ~10-second timeout.)
  10          
  11          
  12             COPYRIGHT
  13             ---------
  14          
  15             This code is associated with the book:
  16          
  17             EMBEDDED C by Michael J. Pont 
  18             [Pearson Education, 2002: ISBN: 0-201-79523-X].
  19          
  20             This code is copyright (c) 2001 by Michael J. Pont.
  21           
  22             See book for copyright details and other information.
  23          
  24          -*------------------------------------------------------------------*/
  25          
  26          #include "Main.H"
  27          #include "Port.H"
  28          
  29          #include "Switch_wait_TimeoutL.H"
  30          #include "Delay_T0.h"
  31          #include "TimeoutL.H"
  32          
  33          /*------------------------------------------------------------------*-
  34          
  35            SWITCH_Init()
  36          
  37            Initialization function for the switch library.
  38          
  39          -*------------------------------------------------------------------*/
  40          void SWITCH_Init(void)
  41             {
  42   1         Switch_pin = 1; // Use this pin for input
  43   1         }
  44          
  45          /*------------------------------------------------------------------*-
  46            
  47            SWITCH_Get_Input()
  48          
  49            Reads and debounces a mechanical switch as follows:
  50          
  51            1. If switch is not pressed, return SWITCH_NOT_PRESSED.
  52          
  53            2. If switch is pressed, wait for DEBOUNCE_PERIOD (in ms).
  54               a. If switch is not pressed, return SWITCH_NOT_PRESSED. 
  55               b. If switch is pressed, wait (with timeout) for
C51 COMPILER V7.06   SWITCH_WAIT_TIMEOUTL                                                  12/16/2004 10:23:59 PAGE 2   

  56                  switch to be released.  If it times out,
  57                  then return SWITCH_NOT_PRESSED: otherwise, return
  58                  SWITCH_PRESSED.
  59          
  60            See Switch_Wait.H for details of return values.
  61            
  62          -*------------------------------------------------------------------*/
  63          bit SWITCH_Get_Input(const tByte DEBOUNCE_PERIOD)
  64             {
  65   1         bit Return_value = SWITCH_NOT_PRESSED;
  66   1         tLong Timeout_loop = LOOP_TIMEOUT_INIT_10000ms;
  67   1      
  68   1         if (Switch_pin == 0)
  69   1            {
  70   2            // Switch is pressed
  71   2            
  72   2            // Debounce - just wait...
  73   2            DELAY_T0_Wait(DEBOUNCE_PERIOD);
  74   2      
  75   2            // Check switch again
  76   2            if (Switch_pin == 0)
  77   2               {
  78   3               // Wait until the switch is released.
  79   3               // (WITH TIMEOUT LOOP - 10 seconds)
  80   3               while ((Switch_pin == 0) && (++Timeout_loop != 0));
  81   3      
  82   3                       // Check for timeout
  83   3               if (Timeout_loop == 0)
  84   3                  {
  85   4                  Return_value = SWITCH_NOT_PRESSED;
  86   4                  }
  87   3               if(Switch_pin == 1)
  88   3                  {
  89   4                  Return_value = SWITCH_PRESSED;
  90   4                  }
  91   3               }
  92   2            }
  93   1         
  94   1         // Now (finally) return switch value
  95   1         return Return_value;
  96   1         }
  97          
  98          /*------------------------------------------------------------------*-
  99            ---- END OF FILE -------------------------------------------------
 100          -*------------------------------------------------------------------*/


MODULE INFORMATION:   STATIC OVERLAYABLE
   CODE SIZE        =     78    ----
   CONSTANT SIZE    =   ----    ----
   XDATA SIZE       =   ----    ----
   PDATA SIZE       =   ----    ----
   DATA SIZE        =   ----       4
   IDATA SIZE       =   ----    ----
   BIT SIZE         =   ----       1
END OF MODULE INFORMATION.


C51 COMPILATION COMPLETE.  0 WARNING(S),  0 ERROR(S)