can_17xx_40xx.c

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/*
 * @brief LPC17xx/40xx CAN driver
 *
 * @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 "chip.h"

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

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

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

/* Determine clock for CAN Peripheral */
static CHIP_SYSCTL_CLOCK_T Chip_CAN_DetermineClk(LPC_CAN_T *pCAN) {

 CHIP_SYSCTL_CLOCK_T CanClk;

 if (pCAN == LPC_CAN1) {
  CanClk = SYSCTL_CLOCK_CAN1;
 }
 else {
  CanClk = SYSCTL_CLOCK_CAN2;
 }

 return CanClk;
}

/* Get CAN Clock Rate */
static uint32_t Chip_CAN_GetClockRate(LPC_CAN_T *pCAN) {
#if !defined(CHIP_LPC175X_6X)
 return Chip_Clock_GetPeripheralClockRate();
#else
 if (pCAN == LPC_CAN1) {
  return Chip_Clock_GetPeripheralClockRate(SYSCTL_PCLK_CAN1);
 }
 else {
  return Chip_Clock_GetPeripheralClockRate(SYSCTL_PCLK_CAN2);
 }
#endif
}

#if !defined(CHIP_LPC175X_6X)
/* Determine CAN peripheral for reset*/
static CHIP_SYSCTL_RESET_T Chip_CAN_DetermineReset(LPC_CAN_T *pCAN) {

 CHIP_SYSCTL_RESET_T CanRst;

 if (pCAN == LPC_CAN1) {
  CanRst = SYSCTL_RESET_CAN1;
 }
 else {
  CanRst = SYSCTL_RESET_CAN2;
 }

 return CanRst;
}

#endif /*#if !defined(CHIP_LPC175X_6X)*/

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

/* Initialize CAN Interface */
void Chip_CAN_Init(LPC_CAN_T *pCAN)
{
 /* Enable CAN Clock */
 Chip_Clock_EnablePeriphClock(Chip_CAN_DetermineClk(pCAN));
#if !defined(CHIP_LPC175X_6X)
 Chip_SYSCTL_PeriphReset(Chip_CAN_DetermineReset(pCAN));
#endif

 /* Initialize CAN Peripheral */
 IP_CAN_Init(pCAN);

 /* Initiialize Acceptance filter */
 IP_CAN_AF_Init(LPC_CANAF, LPC_CANAF_RAM);
}

/* De-Initialize CAN Interface */
void Chip_CAN_DeInit(LPC_CAN_T *pCAN)
{
 IP_CAN_DeInit(pCAN);
 Chip_Clock_DisablePeriphClock(Chip_CAN_DetermineClk(pCAN));
}

/* Set CAN Bit Rate */
Status Chip_CAN_SetBitRate(LPC_CAN_T *pCAN, uint32_t BitRate)
{
 IP_CAN_BUS_TIMING_T BusTiming;
 uint32_t result = 0;
 uint8_t NT, TSEG1 = 0, TSEG2 = 0;
 uint32_t CANPclk = 0;
 uint32_t BRP = 0;

 CANPclk = Chip_CAN_GetClockRate(pCAN);
 result = CANPclk / BitRate;

 /* Calculate suitable nominal time value
  * NT (nominal time) = (TSEG1 + TSEG2 + 3)
  * NT <= 24
  * TSEG1 >= 2*TSEG2
  */
 for (NT = 24; NT > 0; NT = NT - 2) {
  if ((result % NT) == 0) {
   BRP = result / NT - 1;

   NT--;

   TSEG2 = (NT / 3) - 1;

   TSEG1 = NT - (NT / 3) - 1;

   break;
  }
 }
 if (NT == 0) {
  return ERROR;
 }

 BusTiming.TESG1 = TSEG1;
 BusTiming.TESG2 = TSEG2;
 BusTiming.BRP = BRP;
 BusTiming.SJW = 3;
 BusTiming.SAM = 0;
 IP_CAN_SetBusTiming(pCAN, &BusTiming);
 return SUCCESS;
}

/* Get Free TxBuf */
CAN_BUFFER_ID Chip_CAN_GetFreeTxBuf(LPC_CAN_T *pCAN)
{
 IP_CAN_BUFFER_ID_T TxBufID = CAN_BUFFER_1;

 /* Select a free buffer */
 for (TxBufID = (IP_CAN_BUFFER_ID_T) 0; TxBufID < CAN_BUFFER_LAST; TxBufID++) {
  if (IP_CAN_GetStatus(pCAN) & CAN_SR_TBS(TxBufID)) {
   break;
  }
 }

 return TxBufID;
}