mrt.c

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/*
 * @brief Multi-Rate Timer (MRT) example
 *
 * @note
 * Copyright(C) NXP Semiconductors, 2012
 * All rights reserved.
 *
 * @par
 * Software that is described herein is for illustrative purposes only
 * which provides customers with programming information regarding the
 * LPC products.  This software is supplied "AS IS" without any warranties of
 * any kind, and NXP Semiconductors and its licensor disclaim any and
 * all warranties, express or implied, including all implied warranties of
 * merchantability, fitness for a particular purpose and non-infringement of
 * intellectual property rights.  NXP Semiconductors assumes no responsibility
 * or liability for the use of the software, conveys no license or rights under any
 * patent, copyright, mask work right, or any other intellectual property rights in
 * or to any products. NXP Semiconductors reserves the right to make changes
 * in the software without notification. NXP Semiconductors also makes no
 * representation or warranty that such application will be suitable for the
 * specified use without further testing or modification.
 *
 * @par
 * Permission to use, copy, modify, and distribute this software and its
 * documentation is hereby granted, under NXP Semiconductors' and its
 * licensor's relevant copyrights in the software, without fee, provided that it
 * is used in conjunction with NXP Semiconductors microcontrollers.  This
 * copyright, permission, and disclaimer notice must appear in all copies of
 * this code.
 */

#include "board.h"

/*****************************************************************************
 * Private types/enumerations/variables
 ****************************************************************************/

#define TICKRATE_HZ     (10) /* 10 ticks per second */
#define RNG_MULTI       (69069)
#define NO_LO_BITS(x)   (x >> 8)

static uint32_t rng = 1234UL;

/*****************************************************************************
 * Public types/enumerations/variables
 ****************************************************************************/

/*****************************************************************************
 * Private functions
 ****************************************************************************/

/* Random No. generator function */
static uint32_t RAND(void)
{
 rng *= RNG_MULTI;
 return (uint32_t) (NO_LO_BITS(rng));/* toss out the low order bits */
}

/*****************************************************************************
 * Public functions
 ****************************************************************************/

void SysTick_Handler(void)
{
 Board_LED_Toggle(1);
 __SEV();
}

void MRT_IRQHandler(void)
{
 uint32_t idx;
    uint32_t int_pend;

    int_pend = Chip_MRT_GetIntPending();
 switch (int_pend) {
 case MRT0_INTFLAG:
  idx = 0;
  break;

 case MRT1_INTFLAG:
  idx = 1;
  break;

 case MRT2_INTFLAG:
  idx = 2;
  break;

 case MRT3_INTFLAG:
  idx = 3;
  break;

 default:/* should never get here */
  while (1) {
   Board_LED_Toggle(0);
  }
 }

 Chip_MRT_IntClear(&LPC_MRT->CHANNEL[idx]);
 Board_LED_Toggle(2);
 __SEV();
}

int main(void)
{
 /* a pointer to a timer */
 LPC_MRT_CHANNEL_T *timer;

 /* Generic Initialization */
 Board_Init();

 /* MRT Initialization */
 Chip_MRT_Init();

 /* Enable SysTick Timer */
 SysTick_Config(SystemCoreClock / TICKRATE_HZ);

    DEBUGSTR("LPC8xx MRT Example \r\n");

 /* Enable the interrupt for the MRT */
 NVIC_EnableIRQ(MRT_IRQn);

 while (1) {
  /* Check if IDLE channel available in MRT */
  if  (Chip_MRT_GetIdleChannel() != LPC_MRT_NO_IDLE_CHANNEL) {
   Board_LED_Set(0, false);

   /* Get channel structure of IDLE channel */
   timer = (LPC_MRT_CHANNEL_T *) (LPC_MRT_BASE + Chip_MRT_GetIdleChannel());

   /* Generate new pseudo-random number */
   RAND();

   /* Configure timer in single-shot mode */
   Chip_MRT_SetMode(timer, MRT_MODE_ONESHOT);

   /* Set some random amount of time interval */
   Chip_MRT_SetInterval(timer, rng / 100);

   /* Enable the channel */
   Chip_MRT_SetEnabled(timer);
  }
  else {
   /* indicate that no timer channel is available */
   Board_LED_Set(0, true);
  }
  __WFE();
 }

 return 0;
}