C51 COMPILER V6.10  DELAY_T0                                                               04/18/2001 16:52:15 PAGE 1   


C51 COMPILER V6.10, COMPILATION OF MODULE DELAY_T0
OBJECT MODULE PLACED IN .\DELAY_T0.OBJ
COMPILER INVOKED BY: C:\KEIL\C51\BIN\C51.EXE .\DELAY_T0.C BROWSE DEBUG OBJECTEXTEND

stmt level    source

   1          /*------------------------------------------------------------------*-
   2          
   3             Delay_T0.C (v1.00)
   4          
   5            ------------------------------------------------------------------
   6          
   7             Simple hardware delays based on T0.
   8          
   9          
  10             COPYRIGHT
  11             ---------
  12          
  13             This code is from the book:
  14          
  15             PATTERNS FOR TIME-TRIGGERED EMBEDDED SYSTEMS by Michael J. Pont 
  16             [Pearson Education, 2001; ISBN: 0-201-33138-1].
  17          
  18             This code is copyright (c) 2001 by Michael J. Pont.
  19           
  20             See book for copyright details and other information.
  21          
  22          -*------------------------------------------------------------------*/
  23          
  24          #include "Main.H"
  25          
  26          // ------ Private constants ----------------------------------------
  27           
  28          // Timer preload values for use in simple (hardware) delays
  29          // - Timers are 16-bit, manual reload ('one shot').
  30          //
  31          // NOTE: These values are portable but timings are *approximate*
  32          //       and *must* be checked by hand if accurate timing is required.
  33          //
  34          // Define Timer 0 / Timer 1 reload values for ~1 msec delay
  35          // NOTE: Adjustment made to allow for function call overheard etc.
  36          #define PRELOAD01  (65536 - (tWord)(OSC_FREQ / (OSC_PER_INST * 1063)))    
  37          #define PRELOAD01H (PRELOAD01 / 256)
  38          #define PRELOAD01L (PRELOAD01 % 256)
  39          
  40          /*------------------------------------------------------------------*-
  41          
  42            Hardware_Delay_T0()
  43          
  44            Function to generate N millisecond delay (approx). 
  45          
  46            Uses Timer 0 (easily adapted to Timer 1).
  47          
  48          -*------------------------------------------------------------------*/
  49          void Hardware_Delay_T0(const tWord N)   
  50             {
  51   1         tWord ms;
  52   1         
  53   1         // Configure Timer 0 as a 16-bit timer 
  54   1         TMOD &= 0xF0; // Clear all T0 bits (T1 left unchanged)
  55   1         TMOD |= 0x01; // Set required T0 bits (T1 left unchanged) 
C51 COMPILER V6.10  DELAY_T0                                                               04/18/2001 16:52:15 PAGE 2   

  56   1      
  57   1         ET0 = 0;  // No interupts
  58   1      
  59   1         // Delay value is *approximately* 1 ms per loop   
  60   1         for (ms = 0; ms < N; ms++)
  61   1            {                 
  62   2            TH0 = PRELOAD01H;  
  63   2            TL0 = PRELOAD01L;   
  64   2      
  65   2            TF0 = 0;          // clear overflow flag
  66   2            TR0 = 1;          // start timer 0
  67   2      
  68   2            while (TF0 == 0); // Loop until Timer 0 overflows (TF0 == 1)
  69   2      
  70   2            TR0 = 0;          // Stop Timer 0
  71   2            }
  72   1         }        
  73          
  74          /*------------------------------------------------------------------*-
  75            ---- END OF FILE -------------------------------------------------
  76          -*------------------------------------------------------------------*/


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)