TMS320F28379S: using one mailbox for multiple Rx messages

Ankit Gupta2

Part Number: TMS320F28379S

HI,

I am trying to use a single mailbox for receiving multiple CAN messages with different message IDs

i am using the below functions to define the message Obj

CANMessageObjInt(ucRXMsg_ECU_001, CAN_MSG_ID_ECU_001, MSG_OBJ_RX_INT_ENABLE, &sRXCAN_ECU_001);
CANMessageSet(CANB_BASE, RX_MSG_OBJ_ID, &sRXCAN_ECU_001, MSG_OBJ_TYPE_RX);


CANMessageObjInt(ucRXMsg_EPC_001, CAN_MSG_ID_EPC_001, MSG_OBJ_RX_INT_ENABLE, &sRXCAN_EPC_001);
CANMessageSet(CANB_BASE, RX_MSG_OBJ_ID, &sRXCAN_EPC_001, MSG_OBJ_TYPE_RX);





/*****************************************************************************
//
//! Initialize the message object that will be used for transmitting CAN messages.
//!
//! \param ucMsgData is the Tx/Rx data array.
//! \param ui32MsgID is the CAN Msg ID.
//! \param ui32MsgFlg Enable CAN int on msg reception or transmission
//! \param pMsgObject is a pointer to a structure containing message object
//! settings.
//!
//!************************************************************************************
*/

void
CANMessageObjInt(unsigned char* ucMsgData, uint32_t ui32MsgID, uint32_t ui32MsgFlg, tCANMsgObject *pMsgObject)
{

// Initialize the message object that will be used for receiving CAN
// messages.
*(unsigned long *)ucMsgData = 0;
pMsgObject->ui32MsgID = ui32MsgID; // CAN message ID - use 1
pMsgObject->ui32MsgIDMask = 0; // 0x7f8; for TX
pMsgObject->ui32Flags = ui32MsgFlg;
pMsgObject->ui32MsgLen = sizeof(ucMsgData);
pMsgObject->pucMsgData = ucMsgData; // ptr to message content

}

CAN_MSG_ID_ECU_001 is defined as 0x010
and

CAN_MSG_ID_EPU_001 is defined as 0x100

When i execute the code and check

i observe that ui32MsgID for both sRXCAN_ECU_001 and sRXCAN_EPC_001 is set as 256 (0x100)
looks like the second command overwrite the earlier command.

am i doing something wrong in initialization?

also i am trying to read the transmitted message by calling

CANMessageGet(CANB_BASE, RX_MSG_OBJ_ID, &sRXCAN_ECU_001, true);

but currently since both the structures have same message ID, the message randomly goes on one.
is their a better way to receive the messages?
can i check for the MsgID and create an If else statement to direct the received message to the correct array?

Thanks
Ankit

over 3 years ago

0 Yashwant Temburu1 over 3 years ago

TI__Expert 4145 points

Hi Ankit,

Some of your images are not properly attached.

You could use filtering and choose to receive all MSGIDs in the same mailbox. Please download Application report http://www.ti.com/lit/sprace5 by Hareesh. It has an example that demonstrates filtering. I also strongly urge you to look at the Debug tips provided.

Application report http://www.ti.com/lit/spracq3 depicts lot of easy to understand waveforms and also provide a tool to introduce error at a chosen bit location.

The TRM chapter explains the CAN protocol implementation in the MCU. i.e. it explains the function of registers/bits. However, it does not explain the protocol itself. For protocol information, refer to these excellent videos:

https://training.ti.com/ti-precision-labs-canlinsbc-can-and-can-fd-protocol?context=1139747-1138099-1139707-1138111

https://training.ti.com/ti-precision-labs-canlinsbc-can-and-can-fd-overview?context=1139747-1138099-1139707-1138109

Regards,

Yashwant

0 Ankit Gupta2 over 3 years ago in reply to Yashwant Temburu1

Prodigy 75 points

Thanks Yashwant for the reply.

I tried adding filtering mask to my code as you suggested, however , now i have an additional doubt regarding storing the received data.

I will be receiving different MsgIDs ranging from 0x010 to 0x4F5

for this i have set the MsgIDMask as 0x000, so as to receive all the messages irrespective of the MSGIDs they have.

once i receive these messages using

CANMessageGet(CANB_BASE, RX_MSG_OBJ_ID, &sRXCANMessage, true);

How can i then copy the messages of a particular MSGID to a particular data array?

Can i use if else statements as

if (sRXCANMessage.ui32MsgID == CAN_MSG_ID_EPU_001)    // CAN_MSG_ID_EPU_001 is defined as 0x100
{
tmp0 += (long)(ucRXMsgData)<<24;
tmp0 += (long)(ucRXMsgData[1])<<16;
tmp0 += (ucRXMsgData[2])<<8;
tmp0 += (ucRXMsgData[3]);
tmp_u32RXMsg1 = tmp0;

}

I am not sure about this as i have initially initialized the mailbox with MSGID 0x010.

Will sRXCANMessage.ui32MsgID contain the value with which it was initialized? or will this value be updated once a message is received?

Thanks

Ankit

0 Yashwant Temburu1 over 3 years ago in reply to Ankit Gupta2

TI__Expert 4145 points

Ankit,

When a Message object is configured to receive using filtering mask, the msg ID is updated based on the received message and it doesnt matter what the object has been initialized with.

So yes you can use that if condition to check for particular msgID.

Regards,

Yashwant

0 Ankit Gupta2 over 3 years ago in reply to Yashwant Temburu1

Prodigy 75 points

Thank you Yashwant. Using the filter mask i was able to solve my issue.

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TMS320F28379S: using one mailbox for multiple Rx messages