switch_read.lst

keil C51 Switch事例

C51 COMPILER V7.06   SWITCH_READ                                                           12/14/2004 09:43:15 PAGE 1   


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

stmt level    source

   1          /*------------------------------------------------------------------*-
   2          
   3             Switch_read.C (v1.00)
   4          
   5            ------------------------------------------------------------------
   6          
   7             A simple 'switch input' program for the 8051.
   8             - Reads (and debounces) switch input on Pin1^0
   9             - If switch is pressed, changes Port 3 output.
  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 <reg52.h>
  27          
  28          // Connect switch to this pin
  29          sbit Switch_pin = P1^0;
  30          
  31          // Display switch status on this port
  32          #define Output_port P3
  33          
  34          // Return values from Switch_Get_Input()
  35          #define SWITCH_NOT_PRESSED (bit) 0 
  36          #define SWITCH_PRESSED (bit) 1 
  37          
  38          // Function prototypes
  39          void SWITCH_Init(void);
  40          bit  SWITCH_Get_Input(const unsigned char); 
  41          void DISPLAY_SWITCH_STATUS_Init(void);
  42          void DISPLAY_SWITCH_STATUS_Update(const bit);
  43          void DELAY_LOOP_Wait(const unsigned int);
  44          
  45          /* ---------------------------------------------------------------- */
  46          void main(void)
  47             {
  48   1         bit Sw_state;
  49   1      
  50   1         // Init functions
  51   1         SWITCH_Init();
  52   1         DISPLAY_SWITCH_STATUS_Init();
  53   1        
  54   1         while(1) 
  55   1            {
C51 COMPILER V7.06   SWITCH_READ                                                           12/14/2004 09:43:15 PAGE 2   

  56   2            Sw_state = SWITCH_Get_Input(30);
  57   2             
  58   2            DISPLAY_SWITCH_STATUS_Update(Sw_state);
  59   2            }
  60   1         }
  61          
  62          /*------------------------------------------------------------------*-
  63          
  64            SWITCH_Init()
  65          
  66            Initialization function for the switch library.
  67          
  68          -*------------------------------------------------------------------*/
  69          void SWITCH_Init(void)
  70             {
  71   1         Switch_pin = 1; // Use this pin for input
  72   1         }
  73          
  74          /*------------------------------------------------------------------*-
  75            
  76            SWITCH_Get_Input()
  77          
  78            Reads and debounces a mechanical switch as follows:
  79          
  80            1. If switch is not pressed, return SWITCH_NOT_PRESSED.
  81          
  82            2. If switch is pressed, wait for DEBOUNCE_PERIOD (in ms).
  83               a. If switch is not pressed, return SWITCH_NOT_PRESSED. 
  84               b. If switch is pressed, wait (indefinitely) for
  85                  switch to be released, then return SWITCH_PRESSED
  86          
  87            See Switch_Wait.H for details of return values.
  88            
  89          -*------------------------------------------------------------------*/
  90          bit SWITCH_Get_Input(const unsigned char DEBOUNCE_PERIOD)
  91             {
  92   1         bit Return_value = SWITCH_NOT_PRESSED;
  93   1      
  94   1         if (Switch_pin == 0)
  95   1            {
  96   2            // Switch is pressed
  97   2            
  98   2            // Debounce - just wait...
  99   2            DELAY_LOOP_Wait(DEBOUNCE_PERIOD);
 100   2      
 101   2            // Check switch again
 102   2            if (Switch_pin == 0)
 103   2               {
 104   3               Return_value = SWITCH_PRESSED;
 105   3               }
 106   2            }
 107   1         
 108   1         // Now return switch value
 109   1         return Return_value;
 110   1         }
 111          
 112          /*------------------------------------------------------------------*-
 113          
 114            DISPLAY_SWITCH_STATUS_Init()
 115          
 116            Initialization function for the DISPLAY_SWITCH_STATUS library.
 117          
C51 COMPILER V7.06   SWITCH_READ                                                           12/14/2004 09:43:15 PAGE 3   

 118          -*------------------------------------------------------------------*/
 119          void DISPLAY_SWITCH_STATUS_Init(void)
 120             {
 121   1         Output_port = 0xF0;
 122   1         }
 123          
 124          /*------------------------------------------------------------------*-
 125          
 126            DISPLAY_SWITCH_STATUS_Update()
 127          
 128            Simple function to display data (SWITCH_STATUS) 
 129            on LEDs connected to port (Output_Port)
 130          
 131          -*------------------------------------------------------------------*/
 132          void DISPLAY_SWITCH_STATUS_Update(const bit SWITCH_STATUS)
 133             {
 134   1         if (SWITCH_STATUS == SWITCH_PRESSED)
 135   1            {
 136   2            Output_port = 0x0F;
 137   2            }
 138   1         else
 139   1            {
 140   2            Output_port = 0xF0;
 141   2            }
 142   1         } 
 143          
 144          /*------------------------------------------------------------------*-
 145          
 146            DELAY_LOOP_Wait()
 147          
 148            Delay duration varies with parameter.  
 149          
 150            Parameter is, *ROUGHLY*, the delay, in milliseconds,
 151            on 12MHz 8051 (12 osc cycles).
 152          
 153            You need to adjust the timing for your application!
 154          
 155          -*------------------------------------------------------------------*/
 156          void DELAY_LOOP_Wait(const unsigned int DELAY_MS)
 157             {
 158   1         unsigned int x, y;
 159   1      
 160   1         for (x = 0; x <= DELAY_MS; x++)
 161   1            {
 162   2            for (y = 0; y <= 120; y++);
 163   2            }
 164   1         }
 165          
 166          
 167          /*------------------------------------------------------------------*-
 168            ---- END OF FILE -------------------------------------------------
 169          -*------------------------------------------------------------------*/


MODULE INFORMATION:   STATIC OVERLAYABLE
   CODE SIZE        =     91    ----
   CONSTANT SIZE    =   ----    ----
   XDATA SIZE       =   ----    ----
   PDATA SIZE       =   ----    ----
   DATA SIZE        =   ----    ----
   IDATA SIZE       =   ----    ----
   BIT SIZE         =   ----       3
C51 COMPILER V7.06   SWITCH_READ                                                           12/14/2004 09:43:15 PAGE 4   

END OF MODULE INFORMATION.


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