Does CONTROL.CONTROL_PBIAS_LITE register exists on AM3517?

RY9983

Other Parts Discussed in Thread: AM3517

Hello,

I am evaluating MMC/SD Interface of AM3517.
TRM (sprugr0b : P2174 19.5.3) describes below.

====
PBIAS_LITE module supplies this bias voltage,
depending on the CONTROL.CONTROL_PBIAS_LITE register settings.

CAUTION
The BIAS voltage must be set using the procedure described in ,
Extended-Drain I/Os and PBIAS Cell Basic Programming Guide. Failure to
follow this procedure can damage the MMCHS interface.
====

But, I can not find CONTROL.CONTROL_PBIAS_LITE on memory map.
(While, BSL source is using it which is defined in 0x48002520)

- Does CONTROL.CONTROL_PBIAS_LITE register exist?
- Should I set CONTROL.CONTROL_PBIAS_LITE register?

Best regards, RY

over 14 years ago

0 Vaibhav Hiremath over 14 years ago

TI__Expert 8180 points

Hi RY,

I believe this register is not applicable for AM3517, this was one of the change in AM3517 as compared to OMAP35x System Control Module. You should not be touching this register from SW.

Thanks,

Vaibhav

0 Jeff Culverhouse over 14 years ago

TI__Genius 9190 points

Hello RY,

Vaibhav is correct, that register was removed from the AM35x devices becuase the IOs for MMC on the AM35x are not extended drain like on the OMAP35x and AM37x devices.

0 RY9983 over 14 years ago in reply to Jeff Culverhouse

Guru 10570 points

Hello, Vaibhav and Jeff.

Thank you so much for the answers.
I am gonna follow your advice.

Best regards, RY

0 MATT GESSNER over 14 years ago in reply to Jeff Culverhouse

Expert 1435 points

If you look at x-loader for the AM3517EVM board, it does:

unsigned char mmc_board_init(void)
{
#if defined (CONFIG_OMAP34XX) && !defined (CONFIG_AM3517EVM)
    unsigned int value = 0;

    value = CONTROL_PBIAS_LITE;
    CONTROL_PBIAS_LITE = value | (1 << 2) | (1 << 1) | (1 << 9);

    value = CONTROL_DEV_CONF0;
    CONTROL_DEV_CONF0 = value | (1 << 24);
#endif
    return 1;
}

Any idea why?

0 Jeff Culverhouse over 14 years ago in reply to MATT GESSNER

TI__Genius 9190 points

hello Matt,

No, it does not exist for AM35x because the IO cells are different. With AM35x we support 1.8 and 3v IO based on the VDDSHV.

0 MATT GESSNER over 14 years ago in reply to Jeff Culverhouse

Expert 1435 points

I guess what I'm getting at is that x-loader, produced by TI, is incorrect. Why? It specifically calls out this board in the above code.

0 Jeff Culverhouse over 14 years ago in reply to MATT GESSNER

TI__Genius 9190 points

Hey Matt,

Sorry, miss read the question. I haven't looked at that portion of the x-loader code, but it looks like it is saying to do that if AM3517EVM is NOT defined.

0 MATT GESSNER over 14 years ago in reply to Jeff Culverhouse

Expert 1435 points

AAARRGGHH!

Sheesh... I feel so foolish now.

Thanks for pointing that out :)

Processors

Processors forum

Does CONTROL.CONTROL_PBIAS_LITE register exists on AM3517?