1 /*
2 * @brief LPC15xx specific stopwatch implementation
3 *
4 * @note
5 * Copyright(C) NXP Semiconductors, 2013
6 * All rights reserved.
7 *
8 * @par
9 * Software that is described herein is for illustrative purposes only
10 * which provides customers with programming information regarding the
11 * LPC products. This software is supplied "AS IS" without any warranties of
12 * any kind, and NXP Semiconductors and its licensor disclaim any and
13 * all warranties, express or implied, including all implied warranties of
14 * merchantability, fitness for a particular purpose and non-infringement of
15 * intellectual property rights. NXP Semiconductors assumes no responsibility
16 * or liability for the use of the software, conveys no license or rights under any
17 * patent, copyright, mask work right, or any other intellectual property rights in
18 * or to any products. NXP Semiconductors reserves the right to make changes
19 * in the software without notification. NXP Semiconductors also makes no
20 * representation or warranty that such application will be suitable for the
21 * specified use without further testing or modification.
22 *
23 * @par
24 * Permission to use, copy, modify, and distribute this software and its
25 * documentation is hereby granted, under NXP Semiconductors' and its
26 * licensor's relevant copyrights in the software, without fee, provided that it
27 * is used in conjunction with NXP Semiconductors microcontrollers. This
28 * copyright, permission, and disclaimer notice must appear in all copies of
29 * this code.
30 */
31
32 #include "chip.h"
33 #include "stopwatch.h"
34
35 /*****************************************************************************
36 * Private types/enumerations/variables
37 ****************************************************************************/
38
39 /* Precompute these to optimize runtime */
40 static uint32_t ticksPerSecond;
41 static uint32_t ticksPerMs;
42 static uint32_t ticksPerUs;
43
44 /*****************************************************************************
45 * Public types/enumerations/variables
46 ****************************************************************************/
47
48 /*****************************************************************************
49 * Private functions
50 ****************************************************************************/
51
52 /*****************************************************************************
53 * Public functions
54 ****************************************************************************/
55
56 /* Initialize stopwatch */
StopWatch_Init(void)57 void StopWatch_Init(void)
58 {
59 /* Use Repetitive Interrupt Timer (RIT) */
60 Chip_RIT_Init(LPC_RITIMER);
61 Chip_RIT_SetCompareValue(LPC_RITIMER, (uint32_t) 0xFFFFFFFF);
62 Chip_RIT_EnableCompClear(LPC_RITIMER);
63 Chip_RIT_Enable(LPC_RITIMER);
64
65 /* Pre-compute tick rate. */
66 ticksPerSecond = Chip_Clock_GetSystemClockRate();
67 ticksPerMs = ticksPerSecond / 1000;
68 ticksPerUs = ticksPerSecond / 1000000;
69 }
70
71 /* Start a stopwatch */
StopWatch_Start(void)72 uint32_t StopWatch_Start(void)
73 {
74 /* Return the current timer count. */
75 return (uint32_t) Chip_RIT_GetCounter(LPC_RITIMER);
76 }
77
78 /* Returns number of ticks per second of the stopwatch timer */
StopWatch_TicksPerSecond(void)79 uint32_t StopWatch_TicksPerSecond(void)
80 {
81 return ticksPerSecond;
82 }
83
84 /* Converts from stopwatch ticks to mS. */
StopWatch_TicksToMs(uint32_t ticks)85 uint32_t StopWatch_TicksToMs(uint32_t ticks)
86 {
87 return ticks / ticksPerMs;
88 }
89
90 /* Converts from stopwatch ticks to uS. */
StopWatch_TicksToUs(uint32_t ticks)91 uint32_t StopWatch_TicksToUs(uint32_t ticks)
92 {
93 return ticks / ticksPerUs;
94 }
95
96 /* Converts from mS to stopwatch ticks. */
StopWatch_MsToTicks(uint32_t mS)97 uint32_t StopWatch_MsToTicks(uint32_t mS)
98 {
99 return mS * ticksPerMs;
100 }
101
102 /* Converts from uS to stopwatch ticks. */
StopWatch_UsToTicks(uint32_t uS)103 uint32_t StopWatch_UsToTicks(uint32_t uS)
104 {
105 return uS * ticksPerUs;
106 }
107