📄 2_01_12h.lst
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C51 COMPILER V6.10 2_01_12H 04/19/2001 11:26:11 PAGE 1
C51 COMPILER V6.10, COMPILATION OF MODULE 2_01_12H
OBJECT MODULE PLACED IN .\2_01_12H.OBJ
COMPILER INVOKED BY: C:\KEIL\C51\BIN\C51.EXE .\2_01_12H.C OPTIMIZE(6,SPEED) BROWSE DEBUG OBJECTEXTEND
stmt level source
1 /*------------------------------------------------------------------*-
2
3 2_01_12h.C (v1.00)
4
5 ------------------------------------------------------------------
6
7 *** THIS IS A *HYBRID* 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_12h.h"
28
29 // ------ Public variable declarations -----------------------------
30
31 // The array of tasks (see Sch51.C)
32 extern sTaskH hSCH_tasks_G[hSCH_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 hSCH_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 hSCH_Init_T2(void)
50 {
51 1 tByte i;
52 1
53 1 for (i = 0; i < hSCH_MAX_TASKS; i++)
54 1 {
55 2 hSCH_Delete_Task(i);
C51 COMPILER V6.10 2_01_12H 04/19/2001 11:26:11 PAGE 2
56 2 }
57 1
58 1 // Reset the global error variable
59 1 // - hSCH_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 hSCH_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 hSCH_Start(void)
99 {
100 1 EA = 1;
101 1 }
102
103 /*------------------------------------------------------------------*-
104
105 hSCH_Update
106
107 This is the scheduler ISR. It is called at a rate
108 determined by the timer settings in hSCH_Init().
109 This version is triggered by Timer 2 interrupts:
110 timer is automatically reloaded.
111
112 -*------------------------------------------------------------------*/
113 void hSCH_Update(void) interrupt INTERRUPT_Timer_2_Overflow
114 {
115 1 tByte Index;
116 1
117 1 TF2 = 0; // Have to manually clear this.
C51 COMPILER V6.10 2_01_12H 04/19/2001 11:26:11 PAGE 3
118 1
119 1 // NOTE: calculations are in *TICKS* (not milliseconds)
120 1 for (Index = 0; Index < hSCH_MAX_TASKS; Index++)
121 1 {
122 2 // Check if there is a task at this location
123 2 if (hSCH_tasks_G[Index].pTask)
124 2 {
125 3 if (hSCH_tasks_G[Index].Delay == 0)
126 3 {
127 4 // The task is due to run
128 4 //
129 4 if (hSCH_tasks_G[Index].Co_op)
130 4 {
131 5 // If it is a co-operative task, increment the RunMe flag
132 5 hSCH_tasks_G[Index].RunMe += 1;
133 5 }
134 4 else
135 4 {
136 5 // If it is a pre-emptive task, run it IMMEDIATELY
137 5 (*hSCH_tasks_G[Index].pTask)(); // Run the task
138 5
139 5 hSCH_tasks_G[Index].RunMe -= 1; // Reset / reduce RunMe flag
140 5
141 5 // Periodic tasks will be run again (see below)
142 5 // - if this is a 'one shot' task, remove it from the array
143 5 if (hSCH_tasks_G[Index].Period == 0)
144 5 {
145 6 hSCH_tasks_G[Index].pTask = 0;
146 6 }
147 5 }
148 4
149 4 if (hSCH_tasks_G[Index].Period)
150 4 {
151 5 // Schedule periodic tasks to run again
152 5 hSCH_tasks_G[Index].Delay = hSCH_tasks_G[Index].Period;
153 5 }
154 4 }
155 3 else
156 3 {
157 4 // Not yet ready to run: just decrement the delay
158 4 hSCH_tasks_G[Index].Delay -= 1;
159 4 }
160 3 }
161 2 }
162 1 }
163
164
165 /*------------------------------------------------------------------*-
166 ---- END OF FILE -------------------------------------------------
167 -*------------------------------------------------------------------*/
MODULE INFORMATION: STATIC OVERLAYABLE
CODE SIZE = 285 ----
CONSTANT SIZE = ---- ----
XDATA SIZE = ---- ----
PDATA SIZE = ---- ----
DATA SIZE = ---- 2
IDATA SIZE = ---- ----
BIT SIZE = ---- ----
END OF MODULE INFORMATION.
C51 COMPILATION COMPLETE. 0 WARNING(S), 0 ERROR(S)
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