OMAP L138 with 375MHz Clock

Alexey Tsirlin

Other Parts Discussed in Thread: OMAP-L138, OMAP-L137, OMAPL138

Hi.

I have noticed that TI released the new OMAP-L138 processor with 375MHz clock. I am using LogicPD development kits with 300MHz processors. Is it possible to overclock those processors to 375MHz? If is understood correctly from the PLL datasheet it is impossible to achieve 375MHz clock with 24MHz crystal which is used in the kit and I must replace the crystal to 25MHz for example, am I right?

Another question is regarding uBoot and Linux. Are there available precompiled binaries for 375MHz clock?

Thanks, Alexey.

over 14 years ago

0 tlee over 14 years ago

TI__Guru 62975 points

Alexey,

You are correct that it is not possible to reach 375MHz with the 24MHz crystal, but you should be able to achieve 372MHz. I believe that the frequency is configured in the boot-strap (UBL) code and uBoot/Linux binaries should work without recompile. You may want to check with the Linux forum to make sure: http://e2e.ti.com/support/embedded/default.aspx

-Tommy

0 Radek Semerad over 14 years ago in reply to tlee

Prodigy 110 points

Hi,

I have the similar question but about 372MHz on OMAP-L137 EVM board with Xtal frequency 24MHz and silicon revision 2.0.

can I use the following dividers/multipliers without having to worry about my chip?

Prediv=2

Pll multiplier=31

Post divider=1

PLLDIV1=1 (default)

PLLDIV2=2 (default)

PLLDIV3=4

PLLDIV4=4 (default)

PLLDIV5=3 (default)

PLLDIV6=1 (default)

Thank you

Radek

0 Mukul Bhatnagar over 14 years ago in reply to Radek Semerad

TI__Guru* 83865 points

This looks ok.

FYI there is clocking spreadsheet calculator

http://processors.wiki.ti.com/index.php/Programming_PLL_Controllers_on_OMAP-L1x8/C674x/AM18xx

Even though this spreadsheet was made for OMAPL138 family, the PLL0 clocking structure /constraints are similar on both OMAPL137 and OMAPL138 , so you should be able to leverage this in conjunction with the device datasheet.

Regards

Mukul

0 Radek Semerad over 14 years ago in reply to Mukul Bhatnagar

Prodigy 110 points

Thank you.

I am stil a bit confused when comparing information about PLL multiplier between SPRUG84c.pdf OMAP-L137 reference guide and SPRS563D.pdf Omap-L137 Datasheet.

Is it true that PLLM in Tab.6-5, line No.5 in OMAP datasheet equals to register value PLLM:[4-0] plus one (chap. 8.4.5 in Reference Guide)?

If it is right then PLL register setting values in table 7.6 (and also e.g. in tab.7.5, 7.8) in Reference Guide are misleading and should be decreased by one (as it is for PLLDIV3 Register Setting in the same table].

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OMAP L138 with 375MHz Clock