TMS320F28069M: CAN STDMSGID and local acceptance mask

Diane Haldeman

Part Number: TMS320F28069M
Other Parts Discussed in Thread: CODECOMPOSER

I've referred to the CAN_LAM example in spra876b, but I'm still struggling to get a single receive mailbox configured that will accept all standard (11-bit) msgids.

So far I've tried:

    //
    // Disable all Mailboxes
    // Required before writing the MSGIDs
    //
    ECanaRegs.CANME.all = 0;
    
    // set the STDMSGIDs to anything, it doesn't matter because all
    // msgids will be transmitted out on mailbox 0, and all
    // msgids will be received on mailbox 1.
    ECanaMboxes.MBOX0.MSGID.all = 0;
    ECanaMboxes.MBOX1.MSGID.all = 0;
    ECanaMboxes.MBOX0.MSGID.bit.STDMSGID = 0x649;
    ECanaMboxes.MBOX1.MSGID.bit.STDMSGID = 0x648;
    
    ECanaMboxes.MBOX1.MSGID.bit.AME = 1;  // use the mbox1 acceptance mask to accept any msgid

    // set the flag indicating standard msgids (11 bit) only
    // IDE = 0 indicates 11 bits
    ECanaMboxes.MBOX0.MSGID.bit.IDE = 0;
    ECanaMboxes.MBOX1.MSGID.bit.IDE = 0;
    
    ECanaShadow.CANMD.all = ECanaRegs.CANMD.all;
    ECanaShadow.CANMD.bit.MD0 = 0;                // mailbox 0 is transmit
    ECanaShadow.CANMD.bit.MD1 = 1;                // mailbox 1 is receive
    ECanaRegs.CANMD.all = ECanaShadow.CANMD.all;
    
    ECanaLAMRegs.LAM1.all  = 0xFFFFFFFF;  // set mbox 1 local acceptance mask to ignore all bits so any msgid is received

    ECanaLAMRegs.LAM1.bit.LAMI = 0;         // mbox 1 IDE bit should determine that only 11 bit msgids should be accepted

    //
    // Enable Mailboxes 0, and 1
    //
    ECanaShadow.CANME.all = 0x00000000;
    ECanaShadow.CANME.bit.ME0 = 1;
    ECanaShadow.CANME.bit.ME1 = 1;
    ECanaRegs.CANME.all = ECanaShadow.CANME.all;
    
    //
    // Specify that 8 bits will be sent/received
    //
    ECanaMboxes.MBOX0.MSGCTRL.bit.DLC = 8;
    ECanaMboxes.MBOX1.MSGCTRL.bit.DLC = 8;

I was able to configure the single transmit mailbox (0) by resetting the ECanaMboxes.MBOX0.MSGID.bit.STDMSGID with every transmission.

But my receive mailbox (1) will only receive standard msgid = 0x648.

Thank you for any suggestions.

over 2 years ago

0 Hareesh Janakiraman over 2 years ago

TI__Guru* 95315 points

Diane,

Are you using the self-test mode or do you actually have two nodes talking to each other?

Please take a look at these and see if they help:

https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/1113379/tms320f2812-can-local-acceptance-mask

https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/732825/can-local-acceptance-mask-problem

https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/574818/tms320f28069-ecan-the-activity-of-the-local-acceptance-mask-when-lami-bit-field-was-clear

0 Diane Haldeman over 2 years ago in reply to Hareesh Janakiraman

Prodigy 160 points

Hareesh,

I have 2 physical CAN nodes talking to each other. And I'm using ESD's CANreal application to monitor/generate CAN traffic.

I suspect I have the ECanaLAMRegs.LAM1 set incorrectly, because the only msgid I can get through is an 11-bit 0x648 (ECanaMboxes.MBOX1.MSGID.bit.STDMSGID = 0x648).

I reviewed the 3 posts you referenced, but I'm still having trouble.

Thank you,

Diane

0 Hareesh Janakiraman over 2 years ago in reply to Diane Haldeman

TI__Guru* 95315 points

Diane,

I will get back to you in a day.

0 Diane Haldeman over 2 years ago in reply to Hareesh Janakiraman

Prodigy 160 points

Hareesh,

Have you had a chance to look into this?

Thank you

0 Hareesh Janakiraman over 2 years ago in reply to Diane Haldeman

TI__Guru* 95315 points

Diane,

Did you verify that the MSGID you configured got written correctly in the mailboxes. You can do this by looking at the RAM area through the memory browser. Note that the STD MSGID is left shifted by 18 counts before being written to the mailbox RAM.

You can also try a 32-bit write into the MSGID register. For example, MBX0 should be written with 0x59240000 for a MSGID of 0x649 with AME=1. MBX1 should be written with 0x59200000 for a MSGID of 0x648 with AME=1.

0 Diane Haldeman over 2 years ago in reply to Hareesh Janakiraman

Prodigy 160 points

Sorry, I think we have a miscommunication.

I'd like the mailbox to be configured to receive any 11-bit std msgid.

I'm using an external application, ESD's CANReal to generate the traffic, and the only msgids that are being received inside my CodeComposer project is 11-bit 0x648.

CANReal let's me specify either an 11-bit or 29-bit msgid:

It's almost as if setting "ECanaMboxes.MBOX1.MSGID.bit.IDE = 0" prevents the LAM from being used.

Thank you

0 Diane Haldeman over 2 years ago in reply to Diane Haldeman

Prodigy 160 points

I found it.

I had to add the following to my CAN initialization:

    EALLOW;
    ECanaShadow.CANMC.all = ECanaRegs.CANMC.all;
    ECanaShadow.CANMC.bit.STM = 0;       /* Configure CAN for normal mode    */
    ECanaShadow.CANMC.bit.SCB = 1;       /* User has selected eCAN mode*/
    ECanaShadow.CANMC.bit.DBO = 1;       /* Set byte order: least significant first*/
    ECanaRegs.CANMC.all = ECanaShadow.CANMC.all;
    EDIS;

Now all 11-bit msgids are being accepted.

Thanks for your help.

0 Joe Prushing over 2 years ago in reply to Diane Haldeman

TI__Genius 16881 points

Hi Diane, Hareesh, is currently out of the office, but we're glad to hear you were able to resolve your issue!

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TMS320F28069M: CAN STDMSGID and local acceptance mask