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TMS320F2800157: Miscalculation in message RAM for MCAN

RIJUTA PUNDIR
Prodigy 30 points
Part Number: TMS320F2800157

MCAN has same message RAM configuration for f2838x, f28003x and f280015x. However, the total number of words given in different TRMs are different. My total calculation, according to the above diagram, give me 4352 words in total. Can you explain why 1024 words are mentioned here for 0015x?

  • 0
    TI__Expert 5635 points

    Rijuta, 

    The ranges available as mentioned in the image above represents the maximum number of elements for each that can be supported by the MCAN module. f2838x has Message RAM (16KB) that can allow for 4352 words. However, other lower cost devices have lesser memory allocated to Message RAM, respectively, 2048 words (8KB) for f28003x and 1024 words (4KB) for f280015x. 

    What this means is that, individually, the MCAN module itself supports up to 128 elements of 11-bit Filters and up to 64 elements of Rx Buffers and so on, however, given the constraints of each device, the application developer needs to make sure to have a Message RAM configuration that does not exceed the available memory. 

    Thanks.

  • 0 in reply to Sahil Deshpande
    Prodigy 30 points

    So according to this, having 64 elements in Rx FIFO for f280015x is never possible, right? As it would require 1152 words and we only have 1024 as available memory. 

  • +1 in reply to RIJUTA PUNDIR
    TI__Expert 5635 points

    Rijuta, 

    One thing to note here is that the size of any RX FIFO element depends on the data size that is set to the MCAN_RXESC register.

     

    You are right that it is not possible to have 64 elements of RX FIFO if the data size is 64 bytes (in which case the total size is 18*64 = 1152 words).

    Thanks.