LPC24XX Memory Accelerator Module (MAM)

[kishu306]

Hello,

   I am using LPC2468 MCU for my product and have come a setting called MAM. According to datasheet , the MAMTIM value depends on the SysClk, which is 72 MHz in my product. So, according to the datasheet , SysClk > 60Mhz, needed value for MAMTIM Register is 4CCLK. We have partially enabled the module.

   My query is to know the effect of this value and what if i assign the value lower than the needed one, for e.g. 1,2 or 3.

Datasheet has a note saying "Warning: These bits set the duration of MAM Flash fetch operations as listed here. Improper setting of this value may result in incorrect operation of the device."

Can you please elaborate what this consequence can be?

[CarlosCasillas]

Hi Kumar,

Have you ensured if the operating temperature of the LPC devices are inside spec?

Have you commented about this behavior with your distributor? Is your distributor part of the official NXP Distribution Network for your country?

https://www.nxp.com/support/sample-buy/distributor-network:DISTRIBUTORS

Hope this will be useful for you.

Best regards!

/Carlos

[CarlosCasillas]

Hi Kumar,

The MAM block maximizes the performance of the ARM processor when it is running code in flash memory. It includes three 128-bit buffers called the Prefetch Buffer, the Branch Trail Buffer and the data buffer. When it is not proper set, some instructions may be corrupted, causing unexpected behavior on the code operation.

You could also take a look at “MAM.1” section of the “Errata sheet LPC2468” document:

https://www.nxp.com/docs/en/errata/ES_LPC2468.pdf

Hope this will be useful for you.
Best regards!
/Carlos

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[kishu306]

Hello Carlos,

   Thank You !!

   We verified the errata of the MCU which you have attached as the link.

   However, it has been rectified in version B on wards & we are using version D controller.

   The question still unanswered is the impact of temperature on MAM? ( Hint: At lower temperature @ 25 degrees, the MCU runs smoothly,, however at higher temperatures > 50 degrees, it malfunctions and MCU Reboots)

Regards,

 Kishore kumar.

[kishu306]

Thank You Carlos !!

However , i have another query following your reply. I have fixed my SysClk to 72MHz and the MAMTIM value at 3. 

One of my product behaves normally but at higher temperatures, it malfunctions. Besides not all of my products behave as i mentioned. Few modules with these settings, run normally even at higher temperatures.

The catch is when i change my MAMTIM value to 4, the modules malfunctioning at higher temperatures also run smoothly. So, the question is that even when my MCU is LPC2468 in all of my modules, why is there a difference in functionality.