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openblt/Target/Source/ARMCM3_LM3S/can.c

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/************************************************************************************//**
* \file Source/ARMCM3_LM3S/can.c
* \brief Bootloader CAN communication interface source file.
* \ingroup Target_ARMCM3_LM3S
* \internal
*----------------------------------------------------------------------------------------
* C O P Y R I G H T
*----------------------------------------------------------------------------------------
* Copyright (c) 2012 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 have received a copy of the GNU General Public License along with OpenBLT. It
* should be located in ".\Doc\license.html". If not, contact Feaser to obtain a copy.
*
* \endinternal
****************************************************************************************/
/****************************************************************************************
* Include files
****************************************************************************************/
#include "boot.h" /* bootloader generic header */
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#if (BOOT_COM_CAN_ENABLE > 0)
#include "driverlib/sysctl.h"
#include "driverlib/canlib.h"
#endif
#if (BOOT_COM_CAN_ENABLE > 0)
/****************************************************************************************
* Macro definitions
****************************************************************************************/
/** \brief Timeout for transmitting a CAN message in milliseconds. */
#define CAN_MSG_TX_TIMEOUT_MS (50u)
/** \brief Index of the used reception message object. */
#define CAN_RX_MSGOBJECT_IDX (0)
/** \brief Index of the used transmission message object. */
#define CAN_TX_MSGOBJECT_IDX (1)
/****************************************************************************************
* Local constant declarations
****************************************************************************************/
/** \brief Lookup table to quickly and efficiently convert a bit number to a bit mask */
static const blt_int16u canBitNum2Mask[] =
{
0x0001, /* bit 0 */
0x0002 /* bit 1 */
};
/************************************************************************************//**
** \brief Attempts to match the bittiming parameters to the requested baudrate
** for a sample point between 65 and 75%, through a linear search
** algorithm. It is based on the equation:
** baudrate = CAN Clock Freq/((1+PropSeg+Phase1Seg+Phase2Seg)*Prescaler)
** \return BLT_TRUE if a valid bittiming configuration was found and set. BLT_FALSE
** otherwise.
**
****************************************************************************************/
static blt_int8u CanSetBittiming(void)
{
tCANBitClkParms bitClkParms;
blt_int8u samplepoint;
/* init SJW to maximum value */
bitClkParms.uSJW = 4;
/* use a double loop to iterate through all possible settings of uSyncPropPhase1Seg
* and uPhase2Seg.
*/
for (bitClkParms.uSyncPropPhase1Seg = 16; bitClkParms.uSyncPropPhase1Seg >= 1; bitClkParms.uSyncPropPhase1Seg--)
{
for (bitClkParms.uPhase2Seg = 8; bitClkParms.uPhase2Seg >= 1; bitClkParms.uPhase2Seg--)
{
samplepoint = ((1+bitClkParms.uSyncPropPhase1Seg) * 100) / (1+bitClkParms.uSyncPropPhase1Seg+bitClkParms.uPhase2Seg);
/* check that sample points is within the preferred range */
if ((samplepoint >= 65) && (samplepoint <= 75))
{
/* does a prescaler exist to get the exact baudrate with these bittiming
* settings?
*/
if ((((BOOT_CPU_XTAL_SPEED_KHZ*1000)/BOOT_COM_CAN_BAUDRATE) % (1+bitClkParms.uSyncPropPhase1Seg+bitClkParms.uPhase2Seg)) == 0)
{
/* bittiming configuration found. now update SJW to that it is never greater
* than one of the phase segments. Giving the fact that the sample point is
* rather high, only phase seg 2 need to be considered for this.
*/
if (bitClkParms.uPhase2Seg < 4)
{
bitClkParms.uSJW = bitClkParms.uPhase2Seg;
}
/* calculate the actual prescaler value */
bitClkParms.uQuantumPrescaler = ((BOOT_CPU_XTAL_SPEED_KHZ*1000)/BOOT_COM_CAN_BAUDRATE)/(1+bitClkParms.uSyncPropPhase1Seg+bitClkParms.uPhase2Seg);
/* apply this bittiming configuration */
CANSetBitTiming(CAN0_BASE, &bitClkParms);
/* break loop and return from function */
return BLT_TRUE;
}
}
}
}
/* no valid bittiming configuration found */
return BLT_FALSE;
} /*** end of CanSetBittiming ***/
/************************************************************************************//**
** \brief Initializes the CAN controller and synchronizes it to the CAN bus.
** \return none.
**
****************************************************************************************/
void CanInit(void)
{
blt_bool result;
tCANMsgObject rxMsgObject;
/* the current implementation supports CAN0. throw an assertion error in case a
* different CAN channel is configured.
*/
ASSERT_CT(BOOT_COM_CAN_CHANNEL_INDEX == 0);
/* enable the CAN controller */
SysCtlPeripheralEnable(SYSCTL_PERIPH_CAN0);
/* reset the state of the CAN controller, including the message objects */
CANInit(CAN0_BASE);
/* set the bittiming */
result = CanSetBittiming();
ASSERT_RT(result == BLT_TRUE);
/* take the CAN controller out of the initialization state */
CANEnable(CAN0_BASE);
/* setup message object 1 to receive the BOOT_COM_CAN_RX_MSG_ID message*/
rxMsgObject.ulMsgID = BOOT_COM_CAN_RX_MSG_ID;
rxMsgObject.ulMsgIDMask = 0x7ff;
rxMsgObject.ulFlags = MSG_OBJ_USE_ID_FILTER;
rxMsgObject.ulMsgLen = 8;
/* is it a 29-bit extended CAN identifier? */
if ((BOOT_COM_CAN_RX_MSG_ID & 0x80000000) != 0)
{
/* configure reception acceptance filter for 29-bit CAN identifier. */
rxMsgObject.ulMsgID &= ~0x80000000;
rxMsgObject.ulMsgIDMask = 0x1fffffff;
rxMsgObject.ulFlags |= MSG_OBJ_EXTENDED_ID;
}
CANMessageSet(CAN0_BASE, CAN_RX_MSGOBJECT_IDX+1, &rxMsgObject, MSG_OBJ_TYPE_RX);
} /*** 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)
{
blt_int32u status;
tCANMsgObject msgObject;
blt_int32u timeout;
/* get bitmask of message objects that are busy transmitting messages */
status = CANStatusGet(CAN0_BASE, CAN_STS_TXREQUEST);
/* make sure that the transmit message object is ready to accept a new message */
ASSERT_RT((status & canBitNum2Mask[CAN_TX_MSGOBJECT_IDX]) == 0);
/* prepare the message and submit it for transmission */
msgObject.ulMsgID = BOOT_COM_CAN_TX_MSG_ID;
msgObject.ulFlags = 0;
/* is it a 29-bit extended CAN identifier? */
if ((BOOT_COM_CAN_TX_MSG_ID & 0x80000000) != 0)
{
msgObject.ulMsgID &= ~0x80000000;
msgObject.ulFlags |= MSG_OBJ_EXTENDED_ID;
}
msgObject.ulMsgLen = len;
msgObject.pucMsgData = data;
CANMessageSet(CAN0_BASE, CAN_TX_MSGOBJECT_IDX+1, &msgObject, MSG_OBJ_TYPE_TX);
/* set timeout time to wait for transmission completion */
timeout = TimerGet() + CAN_MSG_TX_TIMEOUT_MS;
/* now wait for the transmission to complete */
do
{
status = CANStatusGet(CAN0_BASE, CAN_STS_TXREQUEST);
/* service the watchdog */
CopService();
/* break loop upon timeout. this would indicate a hardware failure or no other
* nodes connected to the bus.
*/
if (TimerGet() > timeout)
{
break;
}
}
while ((status & canBitNum2Mask[CAN_TX_MSGOBJECT_IDX]) != 0);
} /*** 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.
** \param len Pointer where the length of the packet is to be stored.
** \return BLT_TRUE is a packet was received, BLT_FALSE otherwise.
**
****************************************************************************************/
blt_bool CanReceivePacket(blt_int8u *data, blt_int8u *len)
{
blt_int32u status;
tCANMsgObject msgObject;
/* get bitmask of message objects with new data */
status = CANStatusGet(CAN0_BASE, CAN_STS_NEWDAT);
/* check if the BOOT_COM_CAN_RX_MSG_ID message was received */
if ((status & canBitNum2Mask[CAN_RX_MSGOBJECT_IDX]) == 0)
{
/* message not received */
return BLT_FALSE;
}
/* read the message data */
msgObject.pucMsgData = data;
CANMessageGet(CAN0_BASE, CAN_RX_MSGOBJECT_IDX+1, &msgObject, true);
*len = msgObject.ulMsgLen;
/* message was successfully received */
return BLT_TRUE;
} /*** end of CanReceivePacket ***/
#endif /* BOOT_COM_CAN_ENABLE > 0 */
/*********************************** end of can.c **************************************/
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