C51 COMPILER V6.10  2_01_12G                                                               03/16/2001 06:57:37 PAGE 1   


C51 COMPILER V6.10, COMPILATION OF MODULE 2_01_12G
OBJECT MODULE PLACED IN .\2_01_12G.OBJ
COMPILER INVOKED BY: C:\KEIL\C51\BIN\C51.EXE .\2_01_12G.C OPTIMIZE(6,SPEED) BROWSE DEBUG OBJECTEXTEND

stmt level    source

   1          /*------------------------------------------------------------------*-
   2          
   3             2_01_12g.C (v1.00) 
   4          
   5            ------------------------------------------------------------------
   6          
   7             *** THIS IS A SCHEDULER FOR STANDARD 8051 / 8052 ***
   8          
   9             *** Uses T2 for timing, 16-bit auto reload ***
  10             *** 12 MHz oscillator -> 1 ms (precise) tick interval ***
  11          
  12          
  13             COPYRIGHT
  14             ---------
  15          
  16             This code is from the book:
  17          
  18             PATTERNS FOR TIME-TRIGGERED EMBEDDED SYSTEMS by Michael J. Pont 
  19             [Pearson Education, 2001; ISBN: 0-201-33138-1].
  20          
  21             This code is copyright (c) 2001 by Michael J. Pont.
  22           
  23             See book for copyright details and other information.
  24          
  25          -*------------------------------------------------------------------*/
  26          
  27          #include "2_01_12g.h"
  28          
  29          // ------ Public variable declarations -----------------------------
  30          
  31          // The array of tasks (see Sch51.C)
  32          extern sTask SCH_tasks_G[SCH_MAX_TASKS];
  33          
  34          // Used to display the error code
  35          // See Main.H for details of error codes
  36          // See Port.H for details of the error port
  37          extern tByte Error_code_G;
  38          
  39          /*------------------------------------------------------------------*-
  40          
  41            SCH_Init_T2()
  42          
  43            Scheduler initialisation function.  Prepares scheduler
  44            data structures and sets up timer interrupts at required rate.
  45          
  46            You must call this function before using the scheduler.  
  47          
  48          -*------------------------------------------------------------------*/
  49          void SCH_Init_T2(void) 
  50             {
  51   1         tByte i;
  52   1      
  53   1         for (i = 0; i < SCH_MAX_TASKS; i++) 
  54   1            {
  55   2            SCH_Delete_Task(i);
C51 COMPILER V6.10  2_01_12G                                                               03/16/2001 06:57:37 PAGE 2   

  56   2            }
  57   1      
  58   1         // Reset the global error variable
  59   1         // - SCH_Delete_Task() will generate an error code, 
  60   1         //   (because the task array is empty)
  61   1         Error_code_G = 0;  
  62   1      
  63   1         // Now set up Timer 2
  64   1         // 16-bit timer function with automatic reload
  65   1      
  66   1         // Crystal is assumed to be 12 MHz
  67   1         // The Timer 2 resolution is 0.000001 seconds (1 祍)
  68   1         // The required Timer 2 overflow is 0.001 seconds (1 ms)
  69   1         // - this takes 1000 timer ticks
  70   1         // Reload value is 65536 - 1000 = 64536 (dec) = 0xFC18
  71   1      
  72   1         T2CON = 0x04;   // load Timer 2 control register
  73   1         T2MOD = 0x00;   // load Timer 2 mode register
  74   1      
  75   1         TH2    = 0xFC;  // load timer 2 high byte
  76   1         RCAP2H = 0xFC;  // load timer 2 reload capture reg, high byte
  77   1         TL2    = 0x18;  // load timer 2 low byte
  78   1         RCAP2L = 0x18;  // load timer 2 reload capture reg, low byte
  79   1         
  80   1         ET2   = 1;  // Timer 2 interrupt is enabled
  81   1      
  82   1         TR2   = 1;  // Start Timer 2
  83   1         }
  84          
  85          
  86          /*------------------------------------------------------------------*-
  87          
  88            SCH_Start()
  89          
  90            Starts the scheduler, by enabling interrupts.
  91          
  92            NOTE: Usually called after all regular tasks are added,
  93            to keep the tasks synchronised.
  94          
  95            NOTE: ONLY THE SCHEDULER INTERRUPT SHOULD BE ENABLED!!! 
  96          
  97          -*------------------------------------------------------------------*/
  98          void SCH_Start(void) 
  99             {
 100   1         EA = 1;
 101   1         }
 102          
 103          /*------------------------------------------------------------------*-
 104          
 105            SCH_Update()
 106          
 107            This is the scheduler ISR.  It is called at a rate 
 108            determined by the timer settings in the 'init' function.
 109          
 110            This version is triggered by Timer 2 interrupts:
 111            timer is automatically reloaded.
 112          
 113          -*------------------------------------------------------------------*/
 114          void SCH_Update(void) interrupt INTERRUPT_Timer_2_Overflow  
 115             {
 116   1         tByte Index;
 117   1      
C51 COMPILER V6.10  2_01_12G                                                               03/16/2001 06:57:37 PAGE 3   

 118   1         TF2 = 0; // Have to manually clear this. 
 119   1      
 120   1         // NOTE: calculations are in *TICKS* (not milliseconds)
 121   1         for (Index = 0; Index < SCH_MAX_TASKS; Index++)
 122   1            {
 123   2            // Check if there is a task at this location
 124   2            if (SCH_tasks_G[Index].pTask)
 125   2               {
 126   3               if (SCH_tasks_G[Index].Delay == 0)
 127   3                  {
 128   4                  // The task is due to run
 129   4                  SCH_tasks_G[Index].RunMe += 1;  // Inc. the 'RunMe' flag
 130   4      
 131   4                  if (SCH_tasks_G[Index].Repeat)
 132   4                     {
 133   5                     // Schedule regular tasks to run again
 134   5                     SCH_tasks_G[Index].Delay = SCH_tasks_G[Index].Repeat;
 135   5                     }
 136   4                  }
 137   3               else
 138   3                  {
 139   4                  // Not yet ready to run: just decrement the delay 
 140   4                  SCH_tasks_G[Index].Delay -= 1;
 141   4                  }
 142   3               }         
 143   2            }
 144   1         }   
 145          
 146          
 147          /*------------------------------------------------------------------*-
 148            ---- END OF FILE -------------------------------------------------
 149          -*------------------------------------------------------------------*/
 150          


MODULE INFORMATION:   STATIC OVERLAYABLE
   CODE SIZE        =    170    ----
   CONSTANT SIZE    =   ----    ----
   XDATA SIZE       =   ----    ----
   PDATA SIZE       =   ----    ----
   DATA SIZE        =   ----       1
   IDATA SIZE       =   ----    ----
   BIT SIZE         =   ----    ----
END OF MODULE INFORMATION.


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