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Can't access McBsp registers from C674x

Anatoliy Sivov
Prodigy 120 points

Hello.

I try to configure McBsp on DM8148 from DSP core. For some reason, I always get some rubish info from McBsp registers.

For an instance, when I try to read SPCR2 (0x47000110) I get two alternating values 0x990d406c and 0x0. And it does not matter, what I try to write to this register (i.e. *((volatile unsigned int*)0x47000110) = 0x80 will result in 0x990d406c and 0x0 on the subsequent reads).

I looked on MMU configuration to ensure it can't be memory translation issue. I get 0x0 from MMU_CNTL. So, DEMMU is disabled.

Also I tried the code on two different dm8148 evm boards. The results are the same.

What could be the reasons of this situation? Should I setup smth. to get access to McBsp registers?

  • 0
    TI__Guru**** 170625 points

    Hello,

    DSP can not access McBSP directly (at physical address 0x47000000), but it should go through the system MMU, which translates the physical addresses to virtual addresses.

    Check here for more info:

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/717/t/243306.aspx

    Regards,

    Pavel