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mrt.c
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1 /*
2 * @brief Multi-Rate Timer (MRT) example
3 *
4 * @note
5 * Copyright(C) NXP Semiconductors, 2012
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 "board.h"
33
61 /*****************************************************************************
62 * Private types/enumerations/variables
63 ****************************************************************************/
64
65 #define TICKRATE_HZ (10) /* 10 ticks per second */
66 #define RNG_MULTI (69069)
67 #define NO_LO_BITS(x) (x >> 8)
68
69 static uint32_t rng = 1234UL;
70
71 /*****************************************************************************
72 * Public types/enumerations/variables
73 ****************************************************************************/
74
75 /*****************************************************************************
76 * Private functions
77 ****************************************************************************/
78
79 /* Random No. generator function */
80 static uint32_t RAND(void)
81 {
82 rng *= RNG_MULTI;
83 return (uint32_t) (NO_LO_BITS(rng));/* toss out the low order bits */
84 }
85
86 /*****************************************************************************
87 * Public functions
88 ****************************************************************************/
89
94 void SysTick_Handler(void)
95 {
96 Board_LED_Toggle(1);
97 __SEV();
98 }
99
104 void MRT_IRQHandler(void)
105 {
106 uint32_t idx;
107 uint32_t int_pend;
108
109 int_pend = Chip_MRT_GetIntPending();
110 switch (int_pend) {
111 case MRT0_INTFLAG:
112 idx = 0;
113 break;
114
115 case MRT1_INTFLAG:
116 idx = 1;
117 break;
118
119 case MRT2_INTFLAG:
120 idx = 2;
121 break;
122
123 case MRT3_INTFLAG:
124 idx = 3;
125 break;
126
127 default:/* should never get here */
128 while (1) {
129 Board_LED_Toggle(0);
130 }
131 }
132
133 Chip_MRT_IntClear(&LPC_MRT->CHANNEL[idx]);
134 Board_LED_Toggle(2);
135 __SEV();
136 }
137
142 int main(void)
143 {
144 /* a pointer to a timer */
145 LPC_MRT_CHANNEL_T *timer;
146
147 /* Generic Initialization */
148 Board_Init();
149
150 /* MRT Initialization */
151 Chip_MRT_Init();
152
153 /* Enable SysTick Timer */
154 SysTick_Config(SystemCoreClock / TICKRATE_HZ);
155
156 DEBUGSTR("LPC8xx MRT Example \r\n");
157
158 /* Enable the interrupt for the MRT */
159 NVIC_EnableIRQ(MRT_IRQn);
160
161 while (1) {
162 /* Check if IDLE channel available in MRT */
163 if (Chip_MRT_GetIdleChannel() != LPC_MRT_NO_IDLE_CHANNEL) {
164 Board_LED_Set(0, false);
165
166 /* Get channel structure of IDLE channel */
167 timer = (LPC_MRT_CHANNEL_T *) (LPC_MRT_BASE + Chip_MRT_GetIdleChannel());
168
169 /* Generate new pseudo-random number */
170 RAND();
171
172 /* Configure timer in single-shot mode */
173 Chip_MRT_SetMode(timer, MRT_MODE_ONESHOT);
174
175 /* Set some random amount of time interval */
176 Chip_MRT_SetInterval(timer, rng / 100);
177
178 /* Enable the channel */
179 Chip_MRT_SetEnabled(timer);
180 }
181 else {
182 /* indicate that no timer channel is available */
183 Board_LED_Set(0, true);
184 }
185 __WFE();
186 }
187
188 return 0;
189 }
190