Questions about FlexRAM

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Questions about FlexRAM

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Contributor III

Hi

I'm using S32k144.

I got two questions studying  EEE

 

1. FlexRAM is slower than SRAM

 

Please see this picture . (it's from AN11983 p11)

help.PNG

When I see flash memory map, I think FlexRAM is also contiguous addresses.

but this is saying non-contiguous...

and is that why the FlexRAM is slower than SRAM?

FlexRAM is not static RAM?

 

2. "a background pattern of all ones" ???

help2.PNG

I saw "a background pattern of all ones" several times in NXP documents..

But I have no idea what it means since I'm not native English speaker,,

 

Please explain to me

 

Thanks

Best regards,

Phillip

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NXP TechSupport
NXP TechSupport

Hello Phillip,


A1

Please refer to the RM, rev.12.1, Section 31.3.2 SRAM accessibility

"To supplement the main system RAM, FlexRAM can be used as system RAM. However,
FlexRAM accesses involve additional system latencies."

This is because FlexRAM is not tightly coupled with the core.

As you can see below, the FlexRAM is a slave on the Crossbar switch.

danielmartynek_0-1599463845985.png

The SRAM_L and SRAM_U regions are contiguous, mapped right next to each other.

But FlexRAM starts at 0x14000000.

danielmartynek_1-1599464169821.png

 

A2.

That simply means that the FlexRAM is initialized with all ones, like each 32b word is written with 0xFFFFFFFF.

 

Regards,

Daniel

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Contributor III

Thanks Daniel. I understood.

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NXP TechSupport
NXP TechSupport

Hello Phillip,


A1

Please refer to the RM, rev.12.1, Section 31.3.2 SRAM accessibility

"To supplement the main system RAM, FlexRAM can be used as system RAM. However,
FlexRAM accesses involve additional system latencies."

This is because FlexRAM is not tightly coupled with the core.

As you can see below, the FlexRAM is a slave on the Crossbar switch.

danielmartynek_0-1599463845985.png

The SRAM_L and SRAM_U regions are contiguous, mapped right next to each other.

But FlexRAM starts at 0x14000000.

danielmartynek_1-1599464169821.png

 

A2.

That simply means that the FlexRAM is initialized with all ones, like each 32b word is written with 0xFFFFFFFF.

 

Regards,

Daniel

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