2 FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
\r
4 ***************************************************************************
\r
8 * + New to FreeRTOS, *
\r
9 * + Wanting to learn FreeRTOS or multitasking in general quickly *
\r
10 * + Looking for basic training, *
\r
11 * + Wanting to improve your FreeRTOS skills and productivity *
\r
13 * then take a look at the FreeRTOS books - available as PDF or paperback *
\r
15 * "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
\r
16 * http://www.FreeRTOS.org/Documentation *
\r
18 * A pdf reference manual is also available. Both are usually delivered *
\r
19 * to your inbox within 20 minutes to two hours when purchased between 8am *
\r
20 * and 8pm GMT (although please allow up to 24 hours in case of *
\r
21 * exceptional circumstances). Thank you for your support! *
\r
23 ***************************************************************************
\r
25 This file is part of the FreeRTOS distribution.
\r
27 FreeRTOS is free software; you can redistribute it and/or modify it under
\r
28 the terms of the GNU General Public License (version 2) as published by the
\r
29 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
\r
30 ***NOTE*** The exception to the GPL is included to allow you to distribute
\r
31 a combined work that includes FreeRTOS without being obliged to provide the
\r
32 source code for proprietary components outside of the FreeRTOS kernel.
\r
33 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
\r
34 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
\r
35 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
\r
36 more details. You should have received a copy of the GNU General Public
\r
37 License and the FreeRTOS license exception along with FreeRTOS; if not it
\r
38 can be viewed here: http://www.freertos.org/a00114.html and also obtained
\r
39 by writing to Richard Barry, contact details for whom are available on the
\r
44 http://www.FreeRTOS.org - Documentation, latest information, license and
\r
47 http://www.SafeRTOS.com - A version that is certified for use in safety
\r
50 http://www.OpenRTOS.com - Commercial support, development, porting,
\r
51 licensing and training services.
\r
54 /* High speed timer test as described in main.c. */
\r
57 /* Scheduler includes. */
\r
58 #include "FreeRTOS.h"
\r
60 /* The set frequency of the interrupt. Deviations from this are measured as
\r
62 #define timerINTERRUPT_FREQUENCY ( ( unsigned portSHORT ) 20000 )
\r
64 /* The expected time between each of the timer interrupts - if the jitter was
\r
66 #define timerEXPECTED_DIFFERENCE_VALUE ( configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY )
\r
68 /* The number of interrupts to pass before we start looking at the jitter. */
\r
69 #define timerSETTLE_TIME 5
\r
70 /*---------------------------------------------------------------------------*/
\r
73 * Configures the two timers used to perform the test.
\r
75 void vSetupTimerTest( void );
\r
77 /* Interrupt handler in which the jitter is measured. */
\r
78 CY_ISR_PROTO(vTimer20KHzISR);
\r
80 /* Stores the value of the maximum recorded jitter between interrupts. */
\r
81 volatile unsigned portSHORT usMaxJitter = 0;
\r
82 /*---------------------------------------------------------------------------*/
\r
84 void vSetupTimerTest( void )
\r
86 /* Install the ISR. */
\r
87 isrTimer_20KHz_TC_StartEx(vTimer20KHzISR);
\r
89 /*---------------------------------------------------------------------------*/
\r
91 CY_ISR(vTimer20KHzISR)
\r
93 static unsigned short usLastCount = 0, usSettleCount = 0, usMaxDifference = 0;
\r
94 unsigned short usThisCount, usDifference;
\r
96 /* Capture the free running timer value as we enter the interrupt. */
\r
97 usThisCount = Timer_48MHz_ReadCounter();
\r
99 if( usSettleCount >= timerSETTLE_TIME )
\r
101 /* What is the difference between the timer value in this interrupt
\r
102 and the value from the last interrupt. Timer counts down. */
\r
103 usDifference = usLastCount + ~usThisCount + 1;
\r
105 /* Store the difference in the timer values if it is larger than the
\r
106 currently stored largest value. The difference over and above the
\r
107 expected difference will give the 'jitter' in the processing of these
\r
109 if( usDifference > usMaxDifference )
\r
111 usMaxDifference = usDifference;
\r
113 /* Calculate the Jitter based on the difference we expect. */
\r
114 usMaxJitter = usMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
\r
119 /* Don't bother storing any values for the first couple of
\r
124 /* Remember what the timer value was this time through, so we can calculate
\r
125 the difference the next time through. */
\r
126 usLastCount = usThisCount;
\r
128 /*---------------------------------------------------------------------------*/
\r