topic Re: Configure multiple identifiers per Flexcan mailbox? in i.MX RT Crossover MCUs

Configure multiple identifiers per Flexcan mailbox?

karl_fraasch — Fri, 26 Apr 2019 13:04:41 GMT

Working with i.MX RT1064

I am wondering if it is possible to configure a single Flexcan mailbox to receive from multiple CAN identifiers. From the documentation, it is not clear to me if masking can be used on a mailbox to effectively allow it to receive messages from multiple identifiers. I understand this can be done with the Rx FIFO.

Re: Configure multiple identifiers per Flexcan mailbox?

jorge_a_vazquez — Wed, 01 May 2019 21:46:26 GMT

Hi Karl Fraasch

You have 3 possible Id filters; Rx global mask for message buffer, Rx FIFO global mask, and Rx individual mask. The global mask is used by buffers 0..13 and buffers 14 and 15 can use their own unique filters/masks. Please consider that the global configuration is only effective when the Rx individual mask is disabled.

With the individual mask, you can filter in an Rx MB. If the Rx FIFO is not enabled, one mask register is provided for each available Mailbox, providing ID masking capability on a per Mailbox basis. If Rx FIFO is enabled, up to 32 Rx Individual Mask Registers can apply to the Rx FIFO ID Filter Table elements on a one-to-one correspondence depending. So you would have to set a filter table. You can check some links as reference:

K10 FlexCan RX FIFO Filter

FlexCAN Fifo SDK 2.0 example

FlexCAN's FIFO function setting and question

Even if the chip is different, you could use them as reference for the Fifo setting.
Have a great day,
TIC

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Re: Configure multiple identifiers per Flexcan mailbox?

karl_fraasch — Thu, 09 May 2019 12:30:49 GMT

Thank you Jorge.

If RX FIFO is enabled (which I believe takes up the first 6 mailboxes), am I still able to configure the other mailboxes with their own individual masks?

For example, I enable RX FIFO and configure 6 Rx mask registers to the Rx FIFO ID Filter Table. Am I still able to configure the remaining 58 mailboxes with their own Id individual mask?

Re: Configure multiple identifiers per Flexcan mailbox?

jorge_a_vazquez — Fri, 10 May 2019 21:42:35 GMT

Hi Karl Fraasch

Following with your questions:

am I still able to configure the other mailboxes with their own individual masks?

Yes, the matching starts from the lowest number Message Buffer toward the higher ones. User should consider which is the first valid MB number considering the FIFO table.

Hope this helps

Regards