max MPU freq 720MHz or 1GHz?

Started by graffiti, April 08, 2015, 06:28:34 PM

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graffiti

Hi,
The webpage for the AM3352-SOM states "Texas Instruments AM3352 Cortex-A8 processor running at 1000MHz", but looking at the schematics I see that the VDD_MPU voltage is stated as 1.25V (within 4%).
According to the OPP figures for the AM335x this voltage is sufficient to run the MPU at 720MHz, but for 1GHz operation ('Nitro OPP') VDD_MPU should be 1.325V nom (min 1.272V, max 1.378V).

Any comments? Are people successfully running the AM3352-SOM at 1GHz without problems?

Thanks,
Kieran.

graffiti

doh, just two posts down I find this thread on the same topic:

https://www.olimex.com/forum/index.php?topic=4291.0

I guess that confirms my concern, although I'm still interested to hear if people are actually managing to run it at 1GHz?

bruceuk

Second that, would like to know how to run at 1Ghz

Chester Gillon

Quote from: graffiti on April 08, 2015, 06:28:34 PMAny comments? Are people successfully running the AM3352-SOM at 1GHz without problems?
I had a quick test of "overclocking" the AM3352-SOM.


When set at 1GHz a SDRAM test was left running for one hour without any errors being reported.


[The test program is a bare-metal application which runs in on-chip RAM so can perform a complete test of all the SDRAM and uses a Code Composer Studio GEL script to set the CPU frequency - haven't investigated how you set the CPU frequency when the AM3352-SOM is running Linux.]


When the CPU frequency was stepped above 1GHz then:
- At 1.3GHz the SDRAM test fails on the first iteration, in that some SDRAM errors are reported and eventually the program crashes.
- At 1.25GHz the SDRAM test ran for 5 minutes without any errors reported (didn't leave running for longer in case caused any damage)


So, you can run the AM3352-SOM at 1GHz without any obvious error, but this was a test with a single board at room temperature so can't guarantee operations across device / temperature / voltage variations.