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AM6421: Topology of R5f subsystems and their TCM on various AM64xx variants

Part Number: AM6421
Other Parts Discussed in Thread: AM6422, AM6412, AM6411

Dear TI team,

for our product we intend to use the AM6421, but we're not sure what the R5f topology really looks like, and how much TCM the R5f cores have in this variant.

My understanding was that the AM6421 has a single R5FSS with two cores, that could operate as two separate cores, in lockstep mode, or a single core with twice the TCM (I'm not 100% sure whether lockstep is actually supported, but that's no relevant to our use case anyway).

The TRM (Rev. E, chapter R5FSS Features) explains that each R5FSS is a dual-core implementation, and that each core in dual-core mode has 64 KB of TCM (32 KB TCMA, 2x16KB TCMB0/1), and that in single-core mode we get 128 KB of TCM (64 KB TCMA, 2x32KB TCMB0/1).

The datasheet says that the AM6421 1x Dual Core R5f.

I would have thought that the AM6421 variant should thus have 128 KB TCM (1x Dual Core == 1x R5FSS = 2x64 KB), but the datasheet (Rev. E) says the AM6421 has 256 KB TCM.

  • How many R5FSS does the AM6421 (and AM6422) have, one or two?
  • How many R5f cores are there per R5FSS on the AM6421?
  • How much TCM does the AM6421 have, and how is it distributed across the R5f cores?

For other products we might consider other variants, and for some of those I don't understand the amount of TCM memory either:

  • The AM6412 and AM6411 have only a single R5f core, but according to the datasheet have 128 KB TCM. Is this correct? I would have expected the single R5f to have just 64 KB, but maybe the memory "is just there anyway", and so the single core really got the full 128 KB.