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openblt/Target/Source/ARMCM3_LM3S/can.c

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/****************************************************************************************
| Description: bootloader CAN communication interface source file
| File Name: can.c
|
|----------------------------------------------------------------------------------------
| 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 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>.
|
****************************************************************************************/
/****************************************************************************************
* 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
****************************************************************************************/
/* index of the used transmission and reception message objects */
#define CAN_RX_MSGOBJECT_IDX (0)
#define CAN_TX_MSGOBJECT_IDX (1)
/****************************************************************************************
* Local constant declarations
****************************************************************************************/
/* 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 */
};
/****************************************************************************************
** NAME: CanSetBittiming
** PARAMETER: none
** RETURN VALUE: BLT_TRUE if a valid bittiming configuration was found and set.
** BLT_FALSE otherwise.
** DESCRIPTION: 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)
**
****************************************************************************************/
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 ***/
/****************************************************************************************
** NAME: CanInit
** PARAMETER: none
** RETURN VALUE: none
** DESCRIPTION: Initializes the CAN controller and synchronizes it to the CAN bus.
**
****************************************************************************************/
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;
CANMessageSet(CAN0_BASE, CAN_RX_MSGOBJECT_IDX+1, &rxMsgObject, MSG_OBJ_TYPE_RX);
} /*** end of CanInit ***/
/****************************************************************************************
** NAME: CanTransmitPacket
** PARAMETER: data pointer to byte array with data that it to be transmitted.
** len number of bytes that are to be transmitted.
** RETURN VALUE: none
** DESCRIPTION: Transmits a packet formatted for the communication interface.
**
****************************************************************************************/
void CanTransmitPacket(blt_int8u *data, blt_int8u len)
{
blt_int32u status;
tCANMsgObject msgObject;
/* 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;
msgObject.ulMsgLen = len;
msgObject.pucMsgData = data;
CANMessageSet(CAN0_BASE, CAN_TX_MSGOBJECT_IDX+1, &msgObject, MSG_OBJ_TYPE_TX);
/* now wait for the transmission to complete */
do
{
status = CANStatusGet(CAN0_BASE, CAN_STS_TXREQUEST);
/* service the watchdog */
CopService();
}
while ((status & canBitNum2Mask[CAN_TX_MSGOBJECT_IDX]) != 0);
} /*** end of CanTransmitPacket ***/
/****************************************************************************************
** NAME: CanReceivePacket
** PARAMETER: data pointer to byte array where the data is to be stored.
** RETURN VALUE: BLT_TRUE is a packet was received, BLT_FALSE otherwise.
** DESCRIPTION: Receives a communication interface packet if one is present.
**
****************************************************************************************/
blt_bool CanReceivePacket(blt_int8u *data)
{
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);
/* message was successfully received */
return BLT_TRUE;
} /*** end of CanReceivePacket ***/
#endif /* BOOT_COM_CAN_ENABLE > 0 */
/*********************************** end of can.c **************************************/
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