Nucleo-L4R5 is kept in reset after downloading sketch

[PerennialNovice]

Hi,

I am experimenting with Nucleo-L4R5 and try to run the CheckVariant example sketch on it.
This sometime succeedes, but most of the time the µC gets stuck in Reset. The red LED is on. When trying to program it with STM32CubeProgramer I get the error "The core is kept under Reset!"
Doing a full chip erase and several resets is able to bring the µC back to normal operation but this just keeps happening very often.
I also tried downloading a simple "blink" example, same result.
When connecting the stuck board to STM32CubeProgrammer, fault analysis is executed and I get the message that DIV_0_TRP bit was enabled.
I suspect this is an error with stm32duino, not with the µC itself, thats why I am writing here.

[PerennialNovice]

Same behaviour on Windows and Linux (Xubuntu in VM)

[fpistm]

Hi @Pestimist
in fact this is not linked to the core.
Issue is under investigation internally as it has been reproduced using application generated thanks STM32CubeIDE.
It has been found with SWAN R5 board, see #1511
As a workaround you can simply use the mass storage upload method.

[PerennialNovice]

Thank you @fpistm for this information
mass storage upload may help here but is not available for the generic variants (I'm still trying to create the L4P5 variant). Is there a possibility to have it available for generic variants?

[fpistm]

Unfortunately not it is too specific to be added to generic upload method.

[PerennialNovice]

too bad
can I make use of the fix you proposed? How could I do that?

[fpistm]

Well you can locally change the GenL4 upload line to add: -ob nBOOT0=0 -ob nBOOT0=1

Arduino_Core_STM32/boards.txt

Line 5089 in 6479b8a

GenL4.menu.upload_method.swdMethod.upload.options=-g

I did not add it as issue seems linked to STM32L4+ and do not want impact all the STM32L4.

[PerennialNovice]

Thank you very much

[PerennialNovice]

After successfully downloading the CheckVariant sketch via SWD the µC started to behave very erratically.

First it was unreacheable, found out that Flash protection registers were changed.
Managed to get them back to normal and program the chip anew.
But the registers keep getting messed up on nearly every programming.
And the chip keeps resetting, output on terminal is as follows:

#####
NUM_DIGITAL_PINS#####
NUM_DIGITAL_PINS#####
NUM_DIGITAL_PINS#####
NUM_DIGITAL_PINS#####
NUM_DIGITAL_PINS#####
NUM_DIGITAL_PINS#####
NUM_DIGITAL_PINS#####
NUM_DIGITAL_PINS#####
NUM_DIGITAL_PINS#####
NUM_DIGITAL_PINS#####
NUM_DIGITAL_PINS#####

This happens regardless how I program the chip (Arduino IDE, Sloeber, STM32programmer, mass storage, SWD)
Even writing registers and resetting the core within STM32Cube Programmer yields the wrong entries in the registers.
seems like the chip itself is broken?

[fpistm]

Yes very strange.
Anyway, what do you want achieve? Nucleo L4R5 is already available in the core?

[PerennialNovice]

I wanted to add the L4P5 variant, did all the steps mentioned here but had no serial output after programming the CheckVariant sketch.
So I tried the sketch wit the L4R5 variant just to make sure all the rest of my setup is working fine.
That is how I ran into all these issues.

[fpistm]

So you tried to add the generic L4P5. If Serial does not work probably that generic SystemCoreConfig is not correct or ldscript as this is what is missing (and off course boards.txt entry addition)

[PerennialNovice]

Yes, but now I also want to get the Nucleo-L4R5 back working, if that is possible.
And I really would like to know what is wrong with it and how I can possibly have caused that.
I don't want to brake another board...

[fpistm]

Well, hard to tell what is wrong. You can try to use the STM32CubeProgrammer and check options bytes.
Also update the STLink Firmware of your board if needed.

[PerennialNovice]

ST-Link firmware update did not change anything.
To be honest I don't really know much about the option bytes, and there are many :)
Anything special you consider worth looking at?
Thanks for your support!

[fpistm]

You can share a screenshot of your OB then I will compare to mine.