delay_t0.lst

Embedded C 这本书的范例光碟程式

C51 COMPILER V7.07   DELAY_T0                                                              06/16/2006 15:36:39 PAGE 1   


C51 COMPILER V7.07, COMPILATION OF MODULE DELAY_T0
OBJECT MODULE PLACED IN Delay_t0.OBJ
COMPILER INVOKED BY: C:\Keil\C51\BIN\C51.EXE Delay_t0.c OPTIMIZE(6,SPEED) BROWSE DEBUG OBJECTEXTEND TABS(3)

stmt level    source

   1          /*
   2             Delay_T0.C (v1.00)
   3             Simple hardware delays based on T0.
   4          */
   5          
   6          #include "Main.H"
   7          
   8          // ------ Private constants ----------------------------------------
   9           
  10          // Timer preload values for use in simple (hardware) delays
  11          // - Timers are 16-bit, manual reload ('one shot').
  12          //
  13          // NOTE: These values are portable but timings are *approximate*
  14          //       and *must* be checked by hand if accurate timing is required.
  15          //
  16          // Define Timer 0 / Timer 1 reload values for ~1 msec delay
  17          // NOTE: Adjustment made to allow for function call overheard etc.
  18          
  19          #define PRELOAD01  (65536 - (tWord)(OSC_FREQ / (OSC_PER_INST * 1020)))    
  20          #define PRELOAD01H (PRELOAD01 / 256)
  21          #define PRELOAD01L (PRELOAD01 % 256)
  22          
  23          /*
  24            DELAY_T0()
  25            Function to generate N millisecond delay (approx). 
  26            Uses Timer 0 (easily adapted to Timer 1).
  27          */
  28          void DELAY_T0_Wait(const tWord N)   
  29          {
  30   1         tWord ms;
  31   1         
  32   1         // Configure Timer 0 as a 16-bit timer 
  33   1         TMOD &= 0xF0; // Clear all T0 bits (T1 left unchanged)
  34   1         TMOD |= 0x01; // Set required T0 bits (T1 left unchanged) 
  35   1      
  36   1         ET0 = 0;  // No interupts
  37   1      
  38   1         // Delay value is *approximately* 1 ms per loop   
  39   1         for (ms = 0; ms < N; ms++)
  40   1         {                 
  41   2            TH0 = PRELOAD01H;  
  42   2            TL0 = PRELOAD01L;   
  43   2      
  44   2            TF0 = 0;          // clear overflow flag
  45   2            TR0 = 1;          // start timer 0
  46   2      
  47   2            while (TF0 == 0); // Loop until Timer 0 overflows (TF0 == 1)
  48   2      
  49   2            TR0 = 0;          // Stop Timer 0
  50   2         }
  51   1      }        
  52          
  53          /*------------------------------------------------------------------*-
  54            ---- END OF FILE -------------------------------------------------
  55          -*------------------------------------------------------------------*/
C51 COMPILER V7.07   DELAY_T0                                                              06/16/2006 15:36:39 PAGE 2   



MODULE INFORMATION:   STATIC OVERLAYABLE
   CODE SIZE        =     41    ----
   CONSTANT SIZE    =   ----    ----
   XDATA SIZE       =   ----    ----
   PDATA SIZE       =   ----    ----
   DATA SIZE        =   ----    ----
   IDATA SIZE       =   ----    ----
   BIT SIZE         =   ----    ----
END OF MODULE INFORMATION.


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