📄 sch51.lst
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59 =1
60 =1 // The maximum number of tasks required at any one time
61 =1 // during the execution of the program
62 =1 //
63 =1 // MUST BE ADJUSTED FOR EACH NEW PROJECT
64 =1 #define SCH_MAX_TASKS (3)
65 =1
66 =1 #endif
67 =1
68 =1 /*------------------------------------------------------------------*-
69 =1 ---- END OF FILE -------------------------------------------------
70 =1 -*------------------------------------------------------------------*/
71 =1
36
37 // ------ Public variable definitions ------------------------------
38
39 // The array of tasks
40 sTask SCH_tasks_G[SCH_MAX_TASKS];
41
42 // Used to display the error code
43 // See Main.H for details of error codes
44 // See Port.H for details of the error port
45 tByte Error_code_G = 0;
46
47 // ------ Private function prototypes ------------------------------
48
49 static void SCH_Go_To_Sleep(void);
50
51 // ------ Private variables ----------------------------------------
52
53 // Keeps track of time since last error was recorded (see below)
54 static tWord Error_tick_count_G;
55
56 // The code of the last error (reset after ~1 minute)
57 static tByte Last_error_code_G;
58
59
60 /*------------------------------------------------------------------*-
61
62 SCH_Dispatch_Tasks()
63
64 This is the 'dispatcher' function. When a task (function)
65 is due to run, SCH_Dispatch_Tasks() will run it.
66 This function must be called (repeatedly) from the main loop.
C51 COMPILER V8.05a SCH51 06/07/2007 19:40:25 PAGE 12
67
68 -*------------------------------------------------------------------*/
69 void SCH_Dispatch_Tasks(void)
70 {
71 1 tByte Index;
72 1
73 1 // Dispatches (runs) the next task (if one is ready)
74 1 for (Index = 0; Index < SCH_MAX_TASKS; Index++)
75 1 {
76 2 if (SCH_tasks_G[Index].RunMe > 0)
77 2 {
78 3 (*SCH_tasks_G[Index].pTask)(); // Run the task
79 3
80 3 SCH_tasks_G[Index].RunMe -= 1; // Reset / reduce RunMe flag
81 3
82 3 // Periodic tasks will automatically run again
83 3 // - if this is a 'one shot' task, remove it from the array
84 3 if (SCH_tasks_G[Index].Period == 0)
85 3 {
86 4 SCH_Delete_Task(Index);
87 4 }
88 3 }
89 2 }
90 1
91 1 // Report system status
92 1 SCH_Report_Status();
93 1
94 1 // The scheduler enters idle mode at this point
95 1 SCH_Go_To_Sleep();
96 1 }
97
98 /*------------------------------------------------------------------*-
99
100 SCH_Add_Task()
101
102 Causes a task (function) to be executed at regular intervals
103 or after a user-defined delay
104
105 Fn_P - The name of the function which is to be scheduled.
106 NOTE: All scheduled functions must be 'void, void' -
107 that is, they must take no parameters, and have
108 a void return type.
109
110 DELAY - The interval (TICKS) before the task is first executed
111
112 PERIOD - If 'PERIOD' is 0, the function is only called once,
113 at the time determined by 'DELAY'. If PERIOD is non-zero,
114 then the function is called repeatedly at an interval
115 determined by the value of PERIOD (see below for examples
116 which should help clarify this).
117
118
119 RETURN VALUE:
120
121 Returns the position in the task array at which the task has been
122 added. If the return value is SCH_MAX_TASKS then the task could
123 not be added to the array (there was insufficient space). If the
124 return value is < SCH_MAX_TASKS, then the task was added
125 successfully.
126
127 Note: this return value may be required, if a task is
128 to be subsequently deleted - see SCH_Delete_Task().
C51 COMPILER V8.05a SCH51 06/07/2007 19:40:25 PAGE 13
129
130 EXAMPLES:
131
132 Task_ID = SCH_Add_Task(Do_X,1000,0);
133 Causes the function Do_X() to be executed once after 1000 sch ticks.
134
135 Task_ID = SCH_Add_Task(Do_X,0,1000);
136 Causes the function Do_X() to be executed regularly, every 1000 sch ticks.
137
138 Task_ID = SCH_Add_Task(Do_X,300,1000);
139 Causes the function Do_X() to be executed regularly, every 1000 ticks.
140 Task will be first executed at T = 300 ticks, then 1300, 2300, etc.
141
142 -*------------------------------------------------------------------*/
143 tByte SCH_Add_Task(void (code * pFunction)(),
144 const tWord DELAY,
145 const tWord PERIOD)
146 {
147 1 tByte Index = 0;
148 1
149 1 // First find a gap in the array (if there is one)
150 1 while ((SCH_tasks_G[Index].pTask != 0) && (Index < SCH_MAX_TASKS))
151 1 {
152 2 Index++;
153 2 }
154 1
155 1 // Have we reached the end of the list?
156 1 if (Index == SCH_MAX_TASKS)
157 1 {
158 2 // Task list is full
159 2 //
160 2 // Set the global error variable
161 2 Error_code_G = ERROR_SCH_TOO_MANY_TASKS;
162 2
163 2 // Also return an error code
164 2 return SCH_MAX_TASKS;
165 2 }
166 1
167 1 // If we're here, there is a space in the task array
168 1 SCH_tasks_G[Index].pTask = pFunction;
169 1
170 1 SCH_tasks_G[Index].Delay = DELAY;
171 1 SCH_tasks_G[Index].Period = PERIOD;
172 1
173 1 SCH_tasks_G[Index].RunMe = 0;
174 1
175 1 return Index; // return position of task (to allow later deletion)
176 1 }
177
178 /*------------------------------------------------------------------*-
179
180 SCH_Delete_Task()
181
182 Removes a task from the scheduler. Note that this does
183 *not* delete the associated function from memory:
184 it simply means that it is no longer called by the scheduler.
185
186 TASK_INDEX - The task index. Provided by SCH_Add_Task().
187
188 RETURN VALUE: RETURN_ERROR or RETURN_NORMAL
189
190 -*------------------------------------------------------------------*/
C51 COMPILER V8.05a SCH51 06/07/2007 19:40:25 PAGE 14
191 bit SCH_Delete_Task(const tByte TASK_INDEX)
192 {
193 1 bit Return_code;
194 1
195 1 if (SCH_tasks_G[TASK_INDEX].pTask == 0)
196 1 {
197 2 // No task at this location...
198 2 //
199 2 // Set the global error variable
200 2 Error_code_G = ERROR_SCH_CANNOT_DELETE_TASK;
201 2
202 2 // ...also return an error code
203 2 Return_code = RETURN_ERROR;
204 2 }
205 1 else
206 1 {
207 2 Return_code = RETURN_NORMAL;
208 2 }
209 1
210 1 SCH_tasks_G[TASK_INDEX].pTask = 0x0000;
211 1 SCH_tasks_G[TASK_INDEX].Delay = 0;
212 1 SCH_tasks_G[TASK_INDEX].Period = 0;
213 1
214 1 SCH_tasks_G[TASK_INDEX].RunMe = 0;
215 1
216 1 return Return_code; // return status
217 1 }
218
219
220 /*------------------------------------------------------------------*-
221
222 SCH_Report_Status()
223
224 Simple function to display error codes.
225
226 This version displays code on a port with attached LEDs:
227 adapt, if required, to report errors over serial link, etc.
228
229 Errors are only displayed for a limited period
230 (60000 ticks = 1 minute at 1ms tick interval).
231 After this the the error code is reset to 0.
232
233 This code may be easily adapted to display the last
234 error 'for ever': this may be appropriate in your
235 application.
236
237 See Chapter 10 for further information.
238
239 -*------------------------------------------------------------------*/
240 void SCH_Report_Status(void)
241 {
242 1 #ifdef SCH_REPORT_ERRORS
243 1 // ONLY APPLIES IF WE ARE REPORTING ERRORS
244 1 // Check for a new error code
245 1 if (Error_code_G != Last_error_code_G)
246 1 {
247 2 // Negative logic on LEDs assumed
248 2 Error_port = 255 - Error_code_G;
249 2
250 2 Last_error_code_G = Error_code_G;
251 2
252 2 if (Error_code_G != 0)
C51 COMPILER V8.05a SCH51 06/07/2007 19:40:25 PAGE 15
253 2 {
254 3 Error_tick_count_G = 60000;
255 3 }
256 2 else
257 2 {
258 3 Error_tick_count_G = 0;
259 3 }
260 2 }
261 1 else
262 1 {
263 2 if (Error_tick_count_G != 0)
264 2 {
265 3 if (--Error_tick_count_G == 0)
266 3 {
267 4 Error_code_G = 0; // Reset error code
268 4 }
269 3 }
270 2 }
271 1 #endif
272 1 }
273
274
275 /*------------------------------------------------------------------*-
276
277 SCH_Go_To_Sleep()
278
279 This scheduler enters 'idle mode' between clock ticks
280 to save power. The next clock tick will return the processor
281 to the normal operating state.
282
283 Note: a slight performance improvement is possible if this
284 function is implemented as a macro, or if the code here is simply
285 pasted into the 'dispatch' function.
286
287 However, by making this a function call, it becomes easier
288 - during development - to assess the performance of the
289 scheduler, using the 'performance analyser' in the Keil
290 hardware simulator. See Chapter 14 for examples for this.
291
292 *** May wish to disable this if using a watchdog ***
293
294 *** ADAPT AS REQUIRED FOR YOUR HARDWARE ***
295
296 -*------------------------------------------------------------------*/
297 void SCH_Go_To_Sleep()
298 {
299 1 PCON |= 0x01; // Enter idle mode (generic 8051 version)
300 1
301 1 // Entering idle mode requires TWO consecutive instructions
302 1 // on 80c515 / 80c505 - to avoid accidental triggering
303 1 //PCON |= 0x01; // Enter idle mode (#1)
304 1 //PCON |= 0x20; // Enter idle mode (#2)
305 1 }
306
307 /*------------------------------------------------------------------*-
308 ---- END OF FILE -------------------------------------------------
309 -*------------------------------------------------------------------*/
C51 COMPILER V8.05a SCH51 06/07/2007 19:40:25 PAGE 16
ASSEMBLY LISTING OF GENERATED OBJECT CODE
; FUNCTION SCH_Dispatch_Tasks (BEGIN)
; SOURCE LINE # 69
; SOURCE LINE # 70
; SOURCE LINE # 74
0000 E4 CLR A
0001 F500 R MOV Index,A
0003 ?C0001:
; SOURCE LINE # 75
; SOURCE LINE # 76
0003 E500 R MOV A,Index
0005 75F007 MOV B,#07H
0008 A4 MUL AB
0009 2400 R ADD A,#LOW SCH_tasks_G+06H
000B F8 MOV R0,A
000C E6 MOV A,@R0
000D D3 SETB C
000E 9400 SUBB A,#00H
0010 4032 JC ?C0003
; SOURCE LINE # 77
; SOURCE LINE # 78
0012 E500 R MOV A,Index
0014 75F007 MOV B,#07H
0017 A4 MUL AB
0018 2400 R ADD A,#LOW SCH_tasks_G
001A F8 MOV R0,A
001B E6 MOV A,@R0
001C FE MOV R6,A
001D 08 INC R0
001E E6 MOV A,@R0
001F AA06 MOV R2,AR6
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