📄 0_05_11g.lst
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C51 COMPILER V6.10 0_05_11G 04/10/2001 11:50:54 PAGE 1
C51 COMPILER V6.10, COMPILATION OF MODULE 0_05_11G
OBJECT MODULE PLACED IN .\0_05_11g.OBJ
COMPILER INVOKED BY: C:\KEIL\C51\BIN\C51.EXE .\0_05_11g.c OPTIMIZE(6,SIZE) BROWSE DEBUG OBJECTEXTEND
stmt level source
1 /*------------------------------------------------------------------*-
2
3 0_05_11g.C (v1.00)
4
5 ------------------------------------------------------------------
6
7 *** THIS IS A SCHEDULER FOR THE STANDARD 8051 ***
8
9 *** Uses T0 for timing, 16-bit, manual reload ***
10
11 *** With 11.059 MHz crystal -> 5ms tick interval ***
12 --- (see 'reload' function for details) ---
13
14
15 COPYRIGHT
16 ---------
17
18 This code is from the book:
19
20 PATTERNS FOR TIME-TRIGGERED EMBEDDED SYSTEMS by Michael J. Pont
21 [Pearson Education, 2001; ISBN: 0-201-33138-1].
22
23 This code is copyright (c) 2001 by Michael J. Pont.
24
25 See book for copyright details and other information.
26
27 -*------------------------------------------------------------------*/
28
29 #include "Main.h"
30 #include "0_05_11g.h"
31
32 // ------ Public variable declarations -----------------------------
33
34 // The array of tasks (see Sch51.C)
35 extern sTask SCH_tasks_G[SCH_MAX_TASKS];
36
37 // Used to display the error code
38 // See Main.H for details of error codes
39 // See Port.H for details of the error port
40 extern tByte Error_code_G;
41
42 // ------ Private function prototypes ------------------------------
43
44 static void SCH_Manual_Timer0_Reload(void);
45
46 /*------------------------------------------------------------------*-
47
48 SCH_Init_T0()
49
50 Scheduler initialisation function. Prepares scheduler
51 data structures and sets up timer interrupts at required rate.
52 You must call this function before using the scheduler.
53
54 -*------------------------------------------------------------------*/
55 void SCH_Init_T0(void)
C51 COMPILER V6.10 0_05_11G 04/10/2001 11:50:54 PAGE 2
56 {
57 1 tByte i;
58 1
59 1 for (i = 0; i < SCH_MAX_TASKS; i++)
60 1 {
61 2 SCH_Delete_Task(i);
62 2 }
63 1
64 1 // Reset the global error variable
65 1 // - SCH_Delete_Task() will generate an error code,
66 1 // (because the task array is empty)
67 1 Error_code_G = 0;
68 1
69 1 // Using Timer 0, 16-bit manual reload
70 1 TMOD &= 0xF0; // Clear all T0 bits (T1 left unchanged)
71 1 TMOD |= 0x01; // Set required T0 bits (T1 left unchanged)
72 1
73 1 // Sets up timer reload values
74 1 SCH_Manual_Timer0_Reload();
75 1
76 1 // Interrupt Timer 0 enabled
77 1 ET0 = 1;
78 1 }
79
80 /*------------------------------------------------------------------*-
81
82 SCH_Start()
83
84 Starts the scheduler, by enabling interrupts.
85
86 NOTE: Usually called after all regular tasks are added,
87 to keep the tasks synchronised.
88
89 NOTE: ONLY THE SCHEDULER INTERRUPT SHOULD BE ENABLED!!!
90
91 -*------------------------------------------------------------------*/
92 void SCH_Start(void)
93 {
94 1 EA = 1;
95 1 }
96
97 /*------------------------------------------------------------------*-
98
99 SCH_Update
100
101 This is the scheduler ISR. It is called at a rate
102 determined by the timer settings in SCH_Init_T0().
103 This version is triggered by Timer 0 interrupts.
104
105 -*------------------------------------------------------------------*/
106 void SCH_Update(void) interrupt INTERRUPT_Timer_0_Overflow
107 {
108 1 tByte Index;
109 1
110 1 // Reload the timer
111 1 SCH_Manual_Timer0_Reload();
112 1
113 1 // NOTE: calculations are in *TICKS* (not milliseconds)
114 1 for (Index = 0; Index < SCH_MAX_TASKS; Index++)
115 1 {
116 2 // Check if there is a task at this location
117 2 if (SCH_tasks_G[Index].pTask)
C51 COMPILER V6.10 0_05_11G 04/10/2001 11:50:54 PAGE 3
118 2 {
119 3 if (SCH_tasks_G[Index].Delay == 0)
120 3 {
121 4 // The task is due to run
122 4 SCH_tasks_G[Index].RunMe += 1; // Inc. the 'Run Me' flag
123 4
124 4 if (SCH_tasks_G[Index].Period)
125 4 {
126 5 // Schedule periodic tasks to run again
127 5 SCH_tasks_G[Index].Delay = SCH_tasks_G[Index].Period;
128 5 }
129 4 }
130 3 else
131 3 {
132 4 // Not yet ready to run: just decrement the delay
133 4 SCH_tasks_G[Index].Delay -= 1;
134 4 }
135 3 }
136 2 }
137 1 }
138
139 /*------------------------------------------------------------------*-
140
141 SCH_Manual_Timer0_Reload()
142
143 This scheduler uses a (manually reloaded) 16-bit timer.
144 The manual reload means that all timings are approximate.
145 THIS SCHEDULER IS NOT SUITABLE FOR APPLICATIONS WHERE
146 ACCURATE TIMING IS REQUIRED!!!
147
148 Timer reload is carried out in this function.
149
150 -*------------------------------------------------------------------*/
151 void SCH_Manual_Timer0_Reload()
152 {
153 1 // Stop Timer 0
154 1 TR0 = 0;
155 1
156 1 // Crystal is assumed to be 11.059 MHz
157 1 // Assume 12 osc cycles per timer increment
158 1 // -> timer resolution is 0.0000010850694 seconds (1.085 祍)
159 1 //
160 1 // The required Timer 0 overflow is 0.005 seconds (5 ms)
161 1 // - this takes 4608 timer ticks
162 1 //
163 1 // Reload value is 65536 - 4608 = 60928 (dec) = 0xEE00
164 1 TH0 = 0xEE;
165 1 TL0 = 0x00;
166 1
167 1 // Start Timer 0
168 1 TR0 = 1;
169 1 }
170
171 /*------------------------------------------------------------------*-
172 ---- END OF FILE -------------------------------------------------
173 -*------------------------------------------------------------------*/
174
MODULE INFORMATION: STATIC OVERLAYABLE
CODE SIZE = 196 ----
CONSTANT SIZE = ---- ----
C51 COMPILER V6.10 0_05_11G 04/10/2001 11:50:54 PAGE 4
XDATA SIZE = ---- ----
PDATA SIZE = ---- ----
DATA SIZE = ---- 1
IDATA SIZE = ---- ----
BIT SIZE = ---- ----
END OF MODULE INFORMATION.
C51 COMPILATION COMPLETE. 0 WARNING(S), 0 ERROR(S)
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