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openblt/Target/Source/ARM7_LPC2000/can.c

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/************************************************************************************//**
* \file Source\ARM7_LPC2000\can.c
* \brief Bootloader CAN communication interface source file.
* \ingroup Target_ARM7_LPC2000
* \internal
*----------------------------------------------------------------------------------------
* C O P Y R I G H T
*----------------------------------------------------------------------------------------
* Copyright (c) 2011 by Feaser http://www.feaser.com All rights reserved
*
*----------------------------------------------------------------------------------------
* L I C E N S E
*----------------------------------------------------------------------------------------
* This file is part of OpenBLT. OpenBLT is free software: you can redistribute it and/or
* modify it under the terms of the GNU General Public License as published by the Free
* Software Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* OpenBLT is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along with OpenBLT.
* If not, see <http://www.gnu.org/licenses/>.
*
* A special exception to the GPL is included to allow you to distribute a combined work
* that includes OpenBLT without being obliged to provide the source code for any
* proprietary components. The exception text is included at the bottom of the license
* file <license.html>.
*
* \endinternal
****************************************************************************************/
/****************************************************************************************
* Include files
****************************************************************************************/
#include "boot.h" /* bootloader generic header */
#if (BOOT_COM_CAN_ENABLE > 0)
/****************************************************************************************
* Macro definitions
****************************************************************************************/
/** \brief Transmit buffer 1 idle bit. */
#define CAN_TBS1 (0x00000004)
/** \brief Transmit buffer 1 complete bit. */
#define CAN_TCS1 (0x00000008)
/** \brief Receive buffer release bit. */
#define CAN_RRB (0x04)
/** \brief Receive buffer status bit. */
#define CAN_RBS (0x01)
/** \brief Transmission request bit. */
#define CAN_TR (0x01)
/** \brief Select tx buffer 1 for transmit bit. */
#define CAN_STB1 (0x20)
/****************************************************************************************
* Register definitions
****************************************************************************************/
/** \brief CANAFMR CAN controller register. */
#define CANAFMR (*((volatile blt_int8u *) 0xE003C000))
/** \brief CAN1MOD CAN controller register. */
#define CAN1MOD (*((volatile blt_int32u *) 0xE0044000))
/** \brief CAN1IER CAN controller register. */
#define CAN1IER (*((volatile blt_int32u *) 0xE0044010))
/** \brief CAN1GSR CAN controller register. */
#define CAN1GSR (*((volatile blt_int32u *) 0xE0044008))
/** \brief CAN1BTR CAN controller register. */
#define CAN1BTR (*((volatile blt_int32u *) 0xE0044014))
/** \brief CAN1TFI1 CAN controller register. */
#define CAN1TFI1 (*((volatile blt_int32u *) 0xE0044030))
/** \brief CAN1TID1 CAN controller register. */
#define CAN1TID1 (*((volatile blt_int32u *) 0xE0044034))
/** \brief CAN1TDA1 CAN controller register. */
#define CAN1TDA1 (*((volatile blt_int32u *) 0xE0044038))
/** \brief CAN1TDB1 CAN controller register. */
#define CAN1TDB1 (*((volatile blt_int32u *) 0xE004403C))
/** \brief CAN1CMR CAN controller register. */
#define CAN1CMR (*((volatile blt_int32u *) 0xE0044004))
/** \brief CAN1SR CAN controller register. */
#define CAN1SR (*((volatile blt_int32u *) 0xE004401C))
/** \brief CAN1RID CAN controller register. */
#define CAN1RID (*((volatile blt_int32u *) 0xE0044024))
/** \brief CAN1RDA CAN controller register. */
#define CAN1RDA (*((volatile blt_int32u *) 0xE0044028))
/** \brief CAN1RDB CAN controller register. */
#define CAN1RDB (*((volatile blt_int32u *) 0xE004402C))
/****************************************************************************************
* Type definitions
****************************************************************************************/
/** \brief Structure type for grouping CAN bus timing related information. */
typedef struct t_can_bus_timing
{
blt_int8u tseg1; /**< CAN time segment 1 */
blt_int8u tseg2; /**< CAN time segment 2 */
} tCanBusTiming;
/****************************************************************************************
* Local constant declarations
****************************************************************************************/
/** \brief CAN bittiming table for dynamically calculating the bittiming settings.
* \details According to the CAN protocol 1 bit-time can be made up of between 8..25
* time quanta (TQ). The total TQ in a bit is SYNC + TSEG1 + TSEG2 with SYNC
* always being 1. The sample point is (SYNC + TSEG1) / (SYNC + TSEG1 + SEG2) *
* 100%. This array contains possible and valid time quanta configurations with
* a sample point between 68..78%.
*/
static const tCanBusTiming canTiming[] =
{ /* TQ | TSEG1 | TSEG2 | SP */
/* ------------------------- */
{ 5, 2 }, /* 8 | 5 | 2 | 75% */
{ 6, 2 }, /* 9 | 6 | 2 | 78% */
{ 6, 3 }, /* 10 | 6 | 3 | 70% */
{ 7, 3 }, /* 11 | 7 | 3 | 73% */
{ 8, 3 }, /* 12 | 8 | 3 | 75% */
{ 9, 3 }, /* 13 | 9 | 3 | 77% */
{ 9, 4 }, /* 14 | 9 | 4 | 71% */
{ 10, 4 }, /* 15 | 10 | 4 | 73% */
{ 11, 4 }, /* 16 | 11 | 4 | 75% */
{ 12, 4 }, /* 17 | 12 | 4 | 76% */
{ 12, 5 }, /* 18 | 12 | 5 | 72% */
{ 13, 5 }, /* 19 | 13 | 5 | 74% */
{ 14, 5 }, /* 20 | 14 | 5 | 75% */
{ 15, 5 }, /* 21 | 15 | 5 | 76% */
{ 15, 6 }, /* 22 | 15 | 6 | 73% */
{ 16, 6 }, /* 23 | 16 | 6 | 74% */
{ 16, 7 }, /* 24 | 16 | 7 | 71% */
{ 16, 8 } /* 25 | 16 | 8 | 68% */
};
/************************************************************************************//**
** \brief Search algorithm to match the desired baudrate to a possible bus
** timing configuration.
** \param baud The desired baudrate in kbps. Valid values are 10..1000.
** \param btr Pointer to where the value for register CANxBTR will be stored.
** \return BLT_TRUE if the CAN bustiming register values were found, BLT_FALSE
** otherwise.
**
****************************************************************************************/
static blt_bool CanGetSpeedConfig(blt_int16u baud, blt_int32u *btr)
{
blt_int16u prescaler;
blt_int8u cnt;
/* loop through all possible time quanta configurations to find a match */
for (cnt=0; cnt < sizeof(canTiming)/sizeof(canTiming[0]); cnt++)
{
if ((BOOT_CPU_SYSTEM_SPEED_KHZ % (baud*(canTiming[cnt].tseg1+canTiming[cnt].tseg2+1))) == 0)
{
/* compute the prescaler that goes with this TQ configuration */
prescaler = BOOT_CPU_SYSTEM_SPEED_KHZ/(baud*(canTiming[cnt].tseg1+canTiming[cnt].tseg2+1));
/* make sure the prescaler is valid */
if ( (prescaler > 0) && (prescaler <= 1024) )
{
/* store the prescaler and bustiming register value */
*btr = prescaler - 1;
*btr |= ((canTiming[cnt].tseg2 - 1) << 20) | ((canTiming[cnt].tseg1 - 1) << 16);
/* found a good bus timing configuration */
return BLT_TRUE;
}
}
}
/* could not find a good bus timing configuration */
return BLT_FALSE;
} /*** end of CanGetSpeedConfig ***/
/************************************************************************************//**
** \brief Initializes the CAN controller and synchronizes it to the CAN bus.
** \return none.
**
****************************************************************************************/
void CanInit(void)
{
blt_bool result;
blt_int32u btr_reg_value=0;
/* the current implementation supports CAN1, which has channel index 0. throw an
* assertion error in case a different CAN channel is configured.
*/
ASSERT_CT(BOOT_COM_CAN_CHANNEL_INDEX == 0);
/* configure acceptance filter for bypass mode so it receives all messages */
CANAFMR = 0x00000002L;
/* take CAN controller offline and go into reset mode */
CAN1MOD = 1;
/* disable all interrupts. driver only needs to work in polling mode */
CAN1IER = 0;
/* reset CAN controller status */
CAN1GSR = 0;
/* configure the bittiming */
result = CanGetSpeedConfig(BOOT_COM_CAN_BAUDRATE/1000, &btr_reg_value);
/* check that a valid baudrate configuration was found */
ASSERT_RT(result == BLT_TRUE);
/* write the bittiming configuration to the register */
CAN1BTR = btr_reg_value;
/* enter normal operating mode and synchronize to the CAN bus */
CAN1MOD = 0;
} /*** end of CanInit ***/
/************************************************************************************//**
** \brief Transmits a packet formatted for the communication interface.
** \param data Pointer to byte array with data that it to be transmitted.
** \param len Number of bytes that are to be transmitted.
** \return none.
**
****************************************************************************************/
void CanTransmitPacket(blt_int8u *data, blt_int8u len)
{
/* check that transmit buffer 1 is ready to accept a new message */
ASSERT_RT((CAN1SR & CAN_TBS1) != 0);
/* write dlc and configure message as a standard message with 11-bit identifier */
CAN1TFI1 = (len << 16);
/* write the message identifier */
CAN1TID1 = BOOT_COM_CAN_TX_MSG_ID;
/* write the first set of 4 data bytes */
CAN1TDA1 = (data[3] << 24) + (data[2] << 16) + (data[1] << 8) + data[0];
/* write the second set of 4 data bytes */
CAN1TDB1 = (data[7] << 24) + (data[6] << 16) + (data[5] << 8) + data[4];
/* write transmission request for transmit buffer 1 */
CAN1CMR = CAN_TR | CAN_STB1;
/* wait for transmit completion */
while ((CAN1SR & CAN_TCS1) == 0)
{
/* keep the watchdog happy */
CopService();
}
} /*** end of CanTransmitPacket ***/
/************************************************************************************//**
** \brief Receives a communication interface packet if one is present.
** \param data Pointer to byte array where the data is to be stored.
** \return BLT_TRUE is a packet was received, BLT_FALSE otherwise.
**
****************************************************************************************/
blt_bool CanReceivePacket(blt_int8u *data)
{
/* check if a new message was received */
if ((CAN1SR & CAN_RBS) == 0)
{
return BLT_FALSE;
}
/* see if this is the message identifier that we are interested in */
if (CAN1RID != BOOT_COM_CAN_RX_MSG_ID)
{
return BLT_FALSE;
}
/* store the message data */
data[0] = (blt_int8u)CAN1RDA;
data[1] = (blt_int8u)(CAN1RDA >> 8);
data[2] = (blt_int8u)(CAN1RDA >> 16);
data[3] = (blt_int8u)(CAN1RDA >> 24);
data[4] = (blt_int8u)CAN1RDB;
data[5] = (blt_int8u)(CAN1RDB >> 8);
data[6] = (blt_int8u)(CAN1RDB >> 16);
data[7] = (blt_int8u)(CAN1RDB >> 24);
/* release the receive buffer */
CAN1CMR = CAN_RRB;
/* inform called that a new data was received */
return BLT_TRUE;
} /*** end of CanReceivePacket ***/
#endif /* BOOT_COM_CAN_ENABLE > 0 */
/*********************************** end of can.c **************************************/
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