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AM6442: Cannot write to RAT memory in M4F for 8th RAT region

Steven Hansen
Intellectual 666 points
Part Number: AM6442
Other Parts Discussed in Thread: SYSCONFIG

On AM64GPEVM, using MCU+ SDK v08_03_00_18, CCS v12.0.0, SysConfig v1.12.1

When setting up more than 7 RAT regions via SysConfig, the 8th region and beyond are not set up. This appears to be an issue with writing to the RAT configuration memory for the M4F.

On M4F, AddrTranslateP_setRegion() attempts to write to 0x442000A0 (and beyond) to set up RAT region 8. However, even after writing to 0x442000A0 the memory at 0x442000A0 remains at 0x00000000. I've connected with JTAG and tried to write to these addresses manually using the memory browser in CCS. The registers at 0x442000A0 and beyond always remain at zero, no matter what is written. But 0x44200000 through 0x4420009C can be written to without problems.

I am using the default SysConfig MPU settings for M4F which maps all memory (other than the 1st 256kB) as Strongly Ordered. None of the other RAT regions touch the 0x40000000 memory space. GP EVM is booted in OSPI boot mode with SBL_NULL and connected via JTAG using the AM64GPEVM target configuration (with associated GELs).

Any ideas what could cause this?

  • +1
    Mastermind 7480 points

    Hi Steven,

    not sure about  how you're counting (zero-based or not), but the M4's RAT seems to have only 8 regions. At offset 0x4 there's the RAT_CONFIG register. In this case the register reads 0x00240108. Bits [7:0] is the REGIONS field, which indicates that this RAT has only 8 regions.

    At offset 0xa0 you'd be accessing the 9th region, which this RAT doesn't have.

    Regards,

    Dominic

  • 0 in reply to Dominic Rath
    Intellectual 666 points

    Hi Dominic,

    That was it, thank you. You are correct that I was attempting to define the 9th RAT region (not 8th, oops, off-by-1 indexing always gets me).

    Unfortunately the TRM is light on information about the RAT, and the M4F RAT section (6.3.3.7) refers to the generic RAT module in Section 8.2, which says "RAT has 16 regions". But I had missed one sentence earlier in 6.3.3.7 that says "It supports 8 regions, with 4KB resolution each".

    If any TI employee sees this, SysConfig should probably limit to 8 RAT regions on the M4F if only to give a clue that there are fewer RAT regions on M4F than R5F.