?? sci_ti2m.lst
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C51 COMPILER V6.10 SCI_TI2M 04/18/2001 16:52:20 PAGE 1
C51 COMPILER V6.10, COMPILATION OF MODULE SCI_TI2M
OBJECT MODULE PLACED IN .\SCI_TI2M.OBJ
COMPILER INVOKED BY: C:\KEIL\C51\BIN\C51.EXE .\SCI_TI2M.C BROWSE DEBUG OBJECTEXTEND
stmt level source
1 /*------------------------------------------------------------------*-
2
3 SCI_Ti2m.c (v1.00)
4
5 ------------------------------------------------------------------
6
7 This is an implementation of SCI SCHEDULER (TICK) for 8051/52.
8
9 --- See Chapter 26 ---
10
11 *** MASTER NODE : TICK-ONLY (DUPLEX) ***
12 *** CHECKS FOR SLAVE ACKNOWLEDEMENTS ***
13
14 *** Uses T2 for timing, 16-bit auto reload ***
15 *** 12 MHz oscillator -> 1 ms (precise) tick interval ***
16
17 --- Assumes '1232' watchdog on Slave ---
18
19
20 COPYRIGHT
21 ---------
22
23 This code is from the book:
24
25 PATTERNS FOR TIME-TRIGGERED EMBEDDED SYSTEMS by Michael J. Pont
26 [Pearson Education, 2001; ISBN: 0-201-33138-1].
27
28 This code is copyright (c) 2001 by Michael J. Pont.
29
30 See book for copyright details and other information.
31
32 -*------------------------------------------------------------------*/
33
34 #include "Main.h"
35 #include "Port.h"
36
37 #include "SCI_Ti2m.H"
38 #include "Delay_T0.h"
39 #include "TLight_A.h"
40
41 // ------ Public variable definitions ------------------------------
42
43 // Used to detect slave activity
44 bit First_call_G;
45 bit Watchdog_input_previous_G;
46
47 // ------ Public variable declarations -----------------------------
48
49 // The array of tasks (see Sch51.c)
50 extern sTask SCH_tasks_G[SCH_MAX_TASKS];
51
52 // The error code variable (see Sch51.c)
53 extern tByte Error_code_G;
54
55 // Used to reset system in event of slave error (see Main.C)
C51 COMPILER V6.10 SCI_TI2M 04/18/2001 16:52:20 PAGE 2
56 extern bit System_reset_G;
57
58 // ------ Private function prototypes ------------------------------
59
60 static void SCI_TICK2_MASTER_Send_Tick_Message(void);
61 static bit SCI_TICK2_MASTER_Process_Ack(void);
62
63 /*------------------------------------------------------------------*-
64
65 SCI_TICK2_MASTER_Init_T2()
66
67 Scheduler initialisation function. Prepares scheduler data
68 structures and sets up timer interrupts at required rate.
69 You must call this function before using the scheduler.
70
71 -*------------------------------------------------------------------*/
72 void SCI_TICK2_MASTER_Init_T2(void)
73 {
74 1 tByte i;
75 1
76 1 // No interrupts (yet)
77 1 EA = 0;
78 1
79 1 // ------ Set up the scheduler ----------------------------------
80 1 // Sort out the tasks
81 1 for (i = 0; i < SCH_MAX_TASKS; i++)
82 1 {
83 2 SCH_Delete_Task(i);
84 2 }
85 1
86 1 // Reset the global error variable
87 1 // - SCH_Delete_Task() will generate an error code,
88 1 // (because the task array is empty)
89 1 Error_code_G = 0;
90 1
91 1 // ------ Set up Timer 2 (begin) --------------------------------
92 1 // Now set up Timer 2
93 1 // 16-bit timer function with automatic reload
94 1
95 1 // Crystal is assumed to be 12 MHz
96 1 // The Timer 2 resolution is 0.000001 seconds (1 祍)
97 1 // The required Timer 2 overflow is 0.001 seconds (1 ms)
98 1 // - this takes 1000 timer ticks
99 1 // Reload value is 65536 - 1000 = 64536 (dec) = 0xFC18
100 1
101 1 T2CON = 0x04; // load Timer 2 control register
102 1 T2MOD = 0x00; // load Timer 2 mode register
103 1
104 1 TH2 = 0xFC; // load timer 2 high byte
105 1 RCAP2H = 0xFC; // load timer 2 reload capture reg, high byte
106 1 TL2 = 0x18; // load timer 2 low byte
107 1 RCAP2L = 0x18; // load timer 2 reload capture reg, low byte
108 1
109 1 ET2 = 1; // Timer 2 interrupt is enabled
110 1
111 1 TR2 = 1; // Start Timer 2
112 1 // ------ Set up Timer 2 (end) ----------------------------------
113 1 }
114
115 /*------------------------------------------------------------------*-
116
117 SCI_TICK2_MASTER_Start()
C51 COMPILER V6.10 SCI_TI2M 04/18/2001 16:52:20 PAGE 3
118
119 Starts the scheduler, by enabling interrupts.
120
121 NOTE: Usually called after all regular tasks are added,
122 to keep the tasks synchronised.
123
124 NOTE: ONLY THE SCHEDULER INTERRUPT SHOULD BE ENABLED!!!
125
126 -*------------------------------------------------------------------*/
127 void SCI_TICK2_MASTER_Start(void)
128 {
129 1 // Try to place system in 'safe' state at start or after errors
130 1 SCI_TICK2_MASTER_Enter_Safe_State();
131 1
132 1 // Delay here to cause the slave to time out and reset
133 1 // Adjust this delay to match the timeout periods on the slaves
134 1 Hardware_Delay_T0(500);
135 1
136 1 // Now send first tick to start the slave
137 1 // (starts on falling edge)
138 1 Interrupt_output_pin = 1;
139 1 Hardware_Delay_T0(5);
140 1 Interrupt_output_pin = 0;
141 1 Hardware_Delay_T0(5);
142 1
143 1 Interrupt_output_pin = 1; // Ready for first tick
144 1
145 1 // Start the scheduler
146 1 EA = 1;
147 1 }
148
149 /*------------------------------------------------------------------*-
150
151 SCI_TICK2_MASTER_Update_T2
152
153 This is the scheduler ISR. It is called at a rate determined by
154 the timer settings in SCI_TICK2_MASTER_Init_T2(). This version is
155 triggered by Timer 2 interrupts: timer is automatically reloaded.
156
157 -*------------------------------------------------------------------*/
158 void SCI_TICK2_MASTER_Update_T2(void) interrupt INTERRUPT_Timer_2_Overflow
159 {
160 1 tByte Index;
161 1
162 1 TF2 = 0; // Must manually clear this.
163 1
164 1 // Get the ack message from the slave
165 1 if (SCI_TICK2_MASTER_Process_Ack() == RETURN_ERROR)
166 1 {
167 2 // Did not receive ack!
168 2 Error_code_G = ERROR_SCH_LOST_SLAVE;
169 2
170 2 // Enter safe state and remain here until reset
171 2 SCI_TICK2_MASTER_Enter_Safe_State();
172 2 while(1);
173 2 }
174 1
175 1 // Send 'tick' message to the slave
176 1 SCI_TICK2_MASTER_Send_Tick_Message();
177 1
178 1 // NOTE: calculations are in *TICKS* (not milliseconds)
179 1 for (Index = 0; Index < SCH_MAX_TASKS; Index++)
C51 COMPILER V6.10 SCI_TI2M 04/18/2001 16:52:20 PAGE 4
180 1 {
181 2 // Check if there is a task at this location
182 2 if (SCH_tasks_G[Index].pTask)
183 2 {
184 3 if (SCH_tasks_G[Index].Delay == 0)
185 3 {
186 4 // The task is due to run
187 4 SCH_tasks_G[Index].RunMe += 1; // Increment the run flag
188 4
189 4 if (SCH_tasks_G[Index].Period)
190 4 {
191 5 // Schedule periodic tasks to run again
192 5 SCH_tasks_G[Index].Delay = SCH_tasks_G[Index].Period;
193 5 }
194 4 }
195 3 else
196 3 {
197 4 // Not yet ready to run: just decrement the delay
198 4 SCH_tasks_G[Index].Delay -= 1;
199 4 }
200 3 }
201 2 }
202 1
203 1 // Prepare for next tick
204 1 Interrupt_output_pin = 1;
205 1 }
206
207 /*------------------------------------------------------------------*-
208
209 SCI_TICK2_MASTER_Send_Tick_Message()
210
211 This function sends a tick message.
212
213 The receipt of this message will cause an interrupt to be generated
214 in the slave(s): this will, in turn, invoke the scheduler 'update'
215 function in the slave(s).
216
217 -*------------------------------------------------------------------*/
218 void SCI_TICK2_MASTER_Send_Tick_Message(void)
219 {
220 1 // Send tick (falling edge) to the slave
221 1 Interrupt_output_pin = 0;
222 1 }
223
224
225 /*------------------------------------------------------------------*-
226
227 SCI_TICK2_MASTER_Process_Ack()
228
229 Checks that the slave is operating.
230
231 -*------------------------------------------------------------------*/
232
233 bit SCI_TICK2_MASTER_Process_Ack(void)
234 {
235 1 if (First_call_G)
236 1 {
237 2 // This is the first time this function has been called
238 2 First_call_G = 0;
239 2
240 2 // Prepare for subsequent checking of the watchdog pin
241 2 Watchdog_input_previous_G = Slave_watchdog_pin;
C51 COMPILER V6.10 SCI_TI2M 04/18/2001 16:52:20 PAGE 5
242 2 }
243 1 else
244 1 {
245 2 // Watchdog pin should change state every time
246 2 // - if the slave is running correctly
247 2 if (Watchdog_input_previous_G == Slave_watchdog_pin)
248 2 {
249 3 // Error!
250 3 return RETURN_ERROR;
251 3 }
252 2
253 2 // Slave is OK
254 2 Watchdog_input_previous_G = Slave_watchdog_pin;
255 2 }
256 1
257 1 return RETURN_NORMAL;
258 1 }
259
260 /*------------------------------------------------------------------*-
261
262 SCI_TICK2_MASTER_Enter_Safe_State()
263
264 This is the state entered by the system when:
265 (1) The node is powered up or reset
266 (2) The slave node fails
267 (3) The network has an error
268 (4) Ack messages are delayed for any other reason
269
270 Try to ensure that the system is in a 'safe' state in these
271 circumstances.
272
273 -*------------------------------------------------------------------*/
274 void SCI_TICK2_MASTER_Enter_Safe_State(void) reentrant
275 {
276 1 // USER DEFINED - Edit as required
277 1
278 1 // Here we display a safe output
279 1 TRAFFIC_LIGHTS_Display_Safe_Output();
280 1 }
281
282 /*------------------------------------------------------------------*-
283 ---- END OF FILE -------------------------------------------------
284 -*------------------------------------------------------------------*/
MODULE INFORMATION: STATIC OVERLAYABLE
CODE SIZE = 277 ----
CONSTANT SIZE = ---- ----
XDATA SIZE = ---- ----
PDATA SIZE = ---- ----
DATA SIZE = ---- 1
IDATA SIZE = ---- ----
BIT SIZE = 2 ----
END OF MODULE INFORMATION.
C51 COMPILATION COMPLETE. 0 WARNING(S), 0 ERROR(S)
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