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After power cycle getting data from SRAM.

HPate.5
Associate II

I have initialized variable as below

uint8_t u8Flag1ForStoreVer __attribute__ ((section (".RAM1_region")));

So, after soft reset I am getting data back.

But also same I am getting after hard reset(Power cycle) , even aftre long time

What should be value in RAM after power on ?

I am using STM32WL controller.

10 REPLIES 10

Indeterminate ​

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HPate.5
Associate II

can we make it zero (Only incase power on) ?

And also in my case mostly I am getting same value not Indeterminate .

KnarfB
Principal III

> can we make it zero

by writing your own software.

> And also in my case mostly I am getting same value not Indeterminate .

There is no guarantee for any specific (deterministic) content and no physical "reset" line in a typical SRAM cell.

hth

KnarfB

I think "frequently the same" fits within the venn diagram I'm drawing.

Perhaps there is significant bulk capacitance in the design, and very low current draw?

I would perhaps look at the RTC or wakeup/standby related status bit. Not an active user of the STM32WL family

Perhaps there's some RAM area cleared via TAMPER ?

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Is a battery / super-cap used in the design?

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No

HPate.5
Associate II

I have tried to write zero on respective address and I am getting that.

But after power on/off , I am still getting default previous value

UPomm
Associate

Controller can supplied parasitic through the protection diodes of the GPIOs from stlink/jlink, if connected.

No its not connected