hardware_delay_50ms.lst

Embedded C 这本书的范例光碟程式

C51 COMPILER V7.07   HARDWARE_DELAY_50MS                                                   06/16/2006 15:10:40 PAGE 1   


C51 COMPILER V7.07, COMPILATION OF MODULE HARDWARE_DELAY_50MS
OBJECT MODULE PLACED IN Hardware_Delay_50ms.OBJ
COMPILER INVOKED BY: C:\Keil\C51\BIN\C51.EXE Hardware_Delay_50ms.c OPTIMIZE(6,SPEED) BROWSE DEBUG OBJECTEXTEND TABS(3)

stmt level    source

   1          /*------------------------------------------------------------------*-
   2             Hardware_Delay_50ms.C (v1.00)
   3            ------------------------------------------------------------------*/
   4          
   5          #include <reg52.h>
   6          
   7          sbit LED_pin = P1^0;
   8           bit LED_state_G;
   9          
  10          void LED_FLASH_Init(void);
  11          void LED_FLASH_Change_State(void);
  12          
  13          void DELAY_HARDWARE_One_Second(void);
  14          void DELAY_HARDWARE_50ms(void);
  15          
  16          void main(void)
  17          {
  18   1         LED_FLASH_Init();
  19   1      
  20   1         while(1) 
  21   1         {
  22   2            LED_FLASH_Change_State();      // Change the LED state (OFF to ON, or vice versa)
  23   2            DELAY_HARDWARE_One_Second();   // Delay for approx 1000 ms
  24   2         }   
  25   1      }
  26          
  27          /*----------------------------------------------------------------
  28            LED_FLASH_Init()
  29            Prepare for LED_Change_State() function - see below.
  30          ------------------------------------------------------------------*/
  31          void LED_FLASH_Init(void)
  32          {
  33   1         LED_state_G = 0;
  34   1      }
  35          
  36          /*------------------------------------------------------------------*-
  37            LED_FLASH_Change_State()
  38            Changes the state of an LED (or pulses a buzzer, etc) on a 
  39            specified port pin.
  40          
  41            Must call at twice the required flash rate: thus, for 1 Hz
  42            flash (on for 0.5 seconds, off for 0.5 seconds) must call
  43            every 0.5 seconds.
  44          
  45          -*------------------------------------------------------------------*/
  46          void LED_FLASH_Change_State(void)
  47          {
  48   1         // Change the LED from OFF to ON (or vice versa)
  49   1         if (LED_state_G == 1)
  50   1         {
  51   2            LED_state_G = 0;
  52   2            LED_pin = 0;
  53   2         }
  54   1         else
  55   1         {
C51 COMPILER V7.07   HARDWARE_DELAY_50MS                                                   06/16/2006 15:10:40 PAGE 2   

  56   2            LED_state_G = 1;
  57   2            LED_pin = 1;
  58   2         }
  59   1      }
  60          
  61          /*******************************************
  62            DELAY_HARDWARE_One_Second()
  63            Hardware delay of 1000 ms.    *** Assumes 12MHz 8051 (12 osc cycles) ***
  64          ********************************************/
  65          
  66          void DELAY_HARDWARE_One_Second(void)
  67          {
  68   1         unsigned char d;
  69   1      
  70   1         for (d = 0; d < 10; d++)   // Call DELAY_HARDWARE_50ms() twenty times
  71   1         {
  72   2            DELAY_HARDWARE_50ms();
  73   2         }     
  74   1      }
  75          
  76          /*******************************************
  77            DELAY_HARDWARE_50ms()
  78            Hardware delay of 50ms.  
  79            *** Assumes 12MHz 8051 (12 osc cycles) ***
  80          ********************************************/
  81          void DELAY_HARDWARE_50ms(void)
  82          {   // Configure Timer 0 as a 16-bit timer 
  83   1         TMOD &= 0xF0; // Clear all T0 bits (T1 left unchanged)
  84   1         TMOD |= 0x01; // Set required T0 bits (T1 left unchanged) 
  85   1      
  86   1         ET0 = 0;  // No interupts
  87   1      
  88   1         // Values for 50 ms delay
  89   1         TH0 = 0x3C;  // Timer 0 initial value (High Byte)
  90   1         TL0 = 0xB0;  // Timer 0 initial value (Low Byte)
  91   1      
  92   1         TF0 = 0;          // Clear overflow flag
  93   1         TR0 = 1;          // Start timer 0
  94   1      
  95   1         while (TF0 == 0); // Loop until Timer 0 overflows (TF0 == 1)
  96   1      
  97   1         TR0 = 0;          // Stop Timer 0
  98   1      }
  99          
 100          


MODULE INFORMATION:   STATIC OVERLAYABLE
   CODE SIZE        =     68    ----
   CONSTANT SIZE    =   ----    ----
   XDATA SIZE       =   ----    ----
   PDATA SIZE       =   ----    ----
   DATA SIZE        =   ----       1
   IDATA SIZE       =   ----    ----
   BIT SIZE         =      1    ----
END OF MODULE INFORMATION.


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