LAUNCHXL-F280049C: About Receive message object in DCAN module

lei li

Hi,

I am using the example "can_ex3_external_transmit". If I receive a data frame from receive message object 1. According to the function "CAN_setupMessageObject", the RX_MSG_OBJ_ID is 1. And then, I want to keep receiving,and I also use "CAN_setupMessageObject" with setting the RX_MSG_OBJ_ID is 2. My question is：the receive message object 1 or 2 is used to receive the second data frame? why? Now, I can't do this experiment yet.

Thanks!

over 4 years ago

0 lei li over 4 years ago

Intellectual 375 points

As far as I know, after the first frame is received by mailbox 1, the valid bit of mailbox 1 is still valid. Even if I configure mailbox 2 to be valid, the second frame is still received by mailbox 1, because mailbox 1 has a higher priority. Is that right? If so, how can I implement my application? The first frame is received by mailbox 1, and the second frame is received by mailbox 2.....

0 Sahil Deshpande over 4 years ago

TI__Expert 6035 points

Hey,

Your query is being looked at, and a solution will be offered shortly.

Thanks.

0 Hareesh Janakiraman over 4 years ago in reply to lei li

TI__Guru* 95315 points

lei li said:
because mailbox 1 has a higher priority. Is that right?

Yes, that is correct. To achieve what you have in mind, you can create a FIFO and make MBX2, the last element in the FIFO. EoB bit of MBX should be 0. EoB of MBX1 should be 1. Please refer to 26.10.5 Configuration of a FIFO Buffer in www.ti.com/lit/spruI33.

0 lei li over 4 years ago in reply to Hareesh Janakiraman

Intellectual 375 points

Thanks for your reply! By the way, if the CAN module want to be exit bus_off to bus_on or bus_idle, MUST I config the ABO bit of CAN_CTL Register?

thanks!

0 Hareesh Janakiraman over 4 years ago in reply to lei li

TI__Guru* 95315 points

Yes, by configuring ABO=1, you enable automatic recovery from a bus-off condition. Else you need to manually clear the Init bit.

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LAUNCHXL-F280049C: About Receive message object in DCAN module