main.c

Revision 36, 7.3 kB (checked in by phil, 15 years ago)
added purchased FreeRTOS book

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1	/*
2	FreeRTOS.org V5.0.4 - Copyright (C) 2003-2008 Richard Barry.
3
4	This file is part of the FreeRTOS.org distribution.
5
6	FreeRTOS.org is free software; you can redistribute it and/or modify
7	it under the terms of the GNU General Public License as published by
8	the Free Software Foundation; either version 2 of the License, or
9	(at your option) any later version.
10
11	FreeRTOS.org is distributed in the hope that it will be useful,
12	but WITHOUT ANY WARRANTY; without even the implied warranty of
13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14	GNU General Public License for more details.
15
16	You should have received a copy of the GNU General Public License
17	along with FreeRTOS.org; if not, write to the Free Software
18	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19
20	A special exception to the GPL can be applied should you wish to distribute
21	a combined work that includes FreeRTOS.org, without being obliged to provide
22	the source code for any proprietary components. See the licensing section
23	of http://www.FreeRTOS.org for full details of how and when the exception
24	can be applied.
25
26	***************************************************************************
27	***************************************************************************
28	* *
29	* SAVE TIME AND MONEY! We can port FreeRTOS.org to your own hardware, *
30	* and even write all or part of your application on your behalf. *
31	* See http://www.OpenRTOS.com for details of the services we provide to *
32	* expedite your project. *
33	* *
34	***************************************************************************
35	***************************************************************************
36
37	Please ensure to read the configuration and relevant port sections of the
38	online documentation.
39
40	http://www.FreeRTOS.org - Documentation, latest information, license and
41	contact details.
42
43	http://www.SafeRTOS.com - A version that is certified for use in safety
44	critical systems.
45
46	http://www.OpenRTOS.com - Commercial support, development, porting,
47	licensing and training services.
48	*/
49
50	/* FreeRTOS.org includes. */
51	#include "FreeRTOS.h"
52	#include "task.h"
53	#include "queue.h"
54
55	/* Demo includes. */
56	#include "basic_io.h"
57
58
59	/* The tasks to be created. Two instances are created of the sender task while
60	only a single instance is created of the receiver task. */
61	static void vSenderTask( void *pvParameters );
62	static void vReceiverTask( void *pvParameters );
63
64	/-----------------------------------------------------------/
65
66	/* Declare a variable of type xQueueHandle. This is used to store the queue
67	that is accessed by all three tasks. */
68	xQueueHandle xQueue;
69
70
71	int main( void )
72	{
73	/* The queue is created to hold a maximum of 5 long values. */
74	xQueue = xQueueCreate( 5, sizeof( long ) );
75
76	if( xQueue != NULL )
77	{
78	/* Create two instances of the task that will write to the queue. The
79	parameter is used to pass the value that the task should write to the queue,
80	so one task will continuously write 100 to the queue while the other task
81	will continuously write 200 to the queue. Both tasks are created at
82	priority 1. */
83	xTaskCreate( vSenderTask, "Sender1", 1000, ( void * ) 100, 1, NULL );
84	xTaskCreate( vSenderTask, "Sender2", 1000, ( void * ) 200, 1, NULL );
85
86	/* Create the task that will read from the queue. The task is created with
87	priority 2, so above the priority of the sender tasks. */
88	xTaskCreate( vReceiverTask, "Receiver", 1000, NULL, 2, NULL );
89
90	/* Start the scheduler so the created tasks start executing. */
91	vTaskStartScheduler();
92	}
93	else
94	{
95	/* The queue could not be created. */
96	}
97
98	/* If all is well we will never reach here as the scheduler will now be
99	running the tasks. If we do reach here then it is likely that there was
100	insufficient heap memory available for a resource to be created. */
101	for( ;; );
102	return 0;
103	}
104	/-----------------------------------------------------------/
105
106	static void vSenderTask( void *pvParameters )
107	{
108	long lValueToSend;
109	portBASE_TYPE xStatus;
110
111	/* Two instances are created of this task so the value that is sent to the
112	queue is passed in via the task parameter rather than be hard coded. This way
113	each instance can use a different value. Cast the parameter to the required
114	type. */
115	lValueToSend = ( long ) pvParameters;
116
117	/* As per most tasks, this task is implemented within an infinite loop. */
118	for( ;; )
119	{
120	/* The first parameter is the queue to which data is being sent. The
121	queue was created before the scheduler was started, so before this task
122	started to execute.
123
124	The second parameter is the address of the data to be sent.
125
126	The third parameter is the Block time the time the task should be kept
127	in the Blocked state to wait for space to become available on the queue
128	should the queue already be full. In this case we dont specify a block
129	time because there should always be space in the queue. */
130	xStatus = xQueueSendToBack( xQueue, &lValueToSend, 0 );
131
132	if( xStatus != pdPASS )
133	{
134	/* We could not write to the queue because it was full this must
135	be an error as the queue should never contain more than one item! */
136	vPrintString( "Could not send to the queue.\r\n" );
137	}
138
139	/* Allow the other sender task to execute. */
140	taskYIELD();
141	}
142	}
143	/-----------------------------------------------------------/
144
145	static void vReceiverTask( void *pvParameters )
146	{
147	/* Declare the variable that will hold the values received from the queue. */
148	long lReceivedValue;
149	portBASE_TYPE xStatus;
150	const portTickType xTicksToWait = 100 / portTICK_RATE_MS;
151
152	/* This task is also defined within an infinite loop. */
153	for( ;; )
154	{
155	/* As this task unblocks immediately that data is written to the queue this
156	call should always find the queue empty. */
157	if( uxQueueMessagesWaiting( xQueue ) != 0 )
158	{
159	vPrintString( "Queue should have been empty!\r\n" );
160	}
161
162	/* The first parameter is the queue from which data is to be received. The
163	queue is created before the scheduler is started, and therefore before this
164	task runs for the first time.
165
166	The second parameter is the buffer into which the received data will be
167	placed. In this case the buffer is simply the address of a variable that
168	has the required size to hold the received data.
169
170	the last parameter is the block time the maximum amount of time that the
171	task should remain in the Blocked state to wait for data to be available should
172	the queue already be empty. */
173	xStatus = xQueueReceive( xQueue, &lReceivedValue, xTicksToWait );
174
175	if( xStatus == pdPASS )
176	{
177	/* Data was successfully received from the queue, print out the received
178	value. */
179	vPrintStringAndNumber( "Received = ", lReceivedValue );
180	}
181	else
182	{
183	/* We did not receive anything from the queue even after waiting for 100ms.
184	This must be an error as the sending tasks are free running and will be
185	continuously writing to the queue. */
186	vPrintString( "Could not receive from the queue.\r\n" );
187	}
188	}
189	}
190
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193
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root/Examples_CP-JR_ARM7_LPC2368/FreeRTOS_Book/Source-Code-For-Examples/Examples/Example010/main.c

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