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XMC configure problem in evmc6678l.gel

Philly
Intellectual 310 points

Other Parts Discussed in Thread: TMS320C6678

Hi,

Recently, I was reading the evmc6678l.gel file which found in MCSDK packet. Here, I have some questions about the xmc_setup() function shows bellow:

According to the C66xx CoerPacs User Guide,  firstly, shouldn't it be 4KB in the note line  /*……(64KB)*/  since the last 5 bit of XMPAX2_H forms  B (01011) ?  then ,why the last 8 bit are  11111111(FF) in XMPAX2_L, you kown there contains 2 reserved bit that is bit 7 & bit6, it's recommended 0 in the C66xx CoerPacs User Guide.

 Still, if the seg size is 4KB, I want to know why it's 4KB instead of 8KB,16KB,etc. Then I checked the memory map in TMS320C6678's datasheet to find out the address that meet the xmc_setup() showed above. It's follows:

Here ,I was confused since the length is just 512B ,but it's defined 4KB in xmc_setup() ,won't it cause memory over flow? Once ,I thought maybe we can use the reserved space followed the 512B DDR3 EMIF configuration space , now I don't think its right . Could you help resolve my confusion? Thanks.

Best Regards,

Philly.

  • 0
    TI__Guru* 81335 points

    Hi Philly,

    As you know, The minimum possible segment size which shall be extended using MPAX configuration is 4KB.

    The physical address translated here is from 1 0000 0000 to 1 0000 0FFF. Except the first 512 bytes, all the other locations were reserved. So it will cause any memory overflow.

    If the programmer wants to use the same logical address to extend other physical address then the programmer shall disable the earlier MPAX configuration.

    Thanks.

  • 0 in reply to Raja
    Intellectual 310 points

    Thanks ,Rajasekaran.

    But, I didn't really figure out what you mean. Though it caused memory overflow, it doesn't matter for the remained space except the first 512B are translated to the reserved space at all ?

    And, are you telling me that the logic address 0x21000000 to 0x21000FFF for DDR3 EMIF configuration space can not only extended  to 0x100000000 to 0x100000FFF, but also other physic address? Despite the memory map summary in TMS320C6678's datasheet , which is the second figure that I posted before.

    Regards,

    Philly