STM32H7S7L8H6H XSPI instability

[Ondrej Meca]

Issue
Higher ambient temperatures cause communication malfunctions with XSPI memories.

Details
Our design is heavily adopted from STM32H7S78-DK which also has the same issue described below.

The application uses memory-mapped mode for both Flash and RAM as the main operational units. These memories are configured in the bootloader and everything generated using CubeMX. According to the datasheets, all three components (CPU, Flash, and RAM) are specified to operate reliably under the given conditions, and they do function correctly under normal temperatures.
The problem arises when the ambient temperature increases from 25°C to 60°C. These temperatures are within the acceptable operating range for all components, as stated in their specifications. Upon reaching higher temperatures, the memories start to exhibit failures. However, further investigation revealed that the issue is not with the memories themselves. When the memories alone are heated, they continue to operate reliably, even at elevated temperatures.
The issue was traced to the CPU. When the CPU is heated, the failures begin around 55°C. At this point, the CPU starts to malfunction in its communication with the memories. This leads to the CPU entering an undefined state, with fault reports showing inconsistent and varying results.
Lowering the temperature restores normal operation.

Investigations

• All supply voltages (VCAP, 3.3V, and 1.8V) remain stable during the issue.
• Heating only the memories while keeping the CPU cooled does not cause the problem; the memories operate reliably under these conditions.
• When heating only the CPU, the problem appears immediately, confirming the issue originates from the CPU.
• Same issue happens on STM32H7S78-DK

Specifications

CPU - STM32H7S7L8H6H
XSPI1 - APS256XXN-OBR-BG
XSPI2 - MX25UW6345GXDI00

STM32CubeMX ver 6.13.0
STM32CubeMX package STM32H7RS v 1.1.0

VCC 3.3V
XSPI1 & XSPI2 1.8V

CPUCPLK 600MHz
HCLK 300MHz
XSPI1 & XSPI2 176MHz with no prescaler

ZIP

schematics, layouts, scatter file, mxcube configs & clocks, option bytes

[taste]

@STOne-32 Since it is the last day of September know is the article available? If not yet please provide a new ETA so I can update my internal action due date. 

[taste]

With mid-October now passed, I'm eager for an update on the article explaining the use of XSPI on the STM32H7. Could you please share a revised availability date? This information is important for my scheduling, and knowing when to expect it would be greatly appreciated.

[STOne-32]

Dear @taste ,

On top of the Article, which is cooking, we planned an official Product Errata-sheet as well for STM32H7RS and planned to be public on web in next couple of weeks, then to trig the Article.

Thank you for the patience.

Regards,

STOne-32.

[STOne-32]

Dear all,

We just released the New Errata sheet here : STM32H7Rxx/7Sxx device errata - Errata sheet

Next step is the Knowledge Article, thank you for the patience.

Regards,

STOne-32.

[taste]

Thank you for releasing this information, it is good to have more details. It also raises questions of course, what to do when not booting at 25-30 degrees Celsius but at a much higher temperature. This can easily happen when rebooting after running at full load in higher ambient temperatures. I hope the knowledge article addresses this.
Are you planning a new silicon revision to fix this bug? 

[austinb]

I just wanted to ping here again and see if we have any updates on the knowledge article. I share the same concern as @taste here, knowing that it is very likely a system boots at temperatures other than 25-30 degrees.

[STOne-32]

Dear @austinb @taste ,

I would propose you to contact your local FAE or official ST office & support to discuss your application use case and understand the constraints.  

The Main purpose of the Errata is to do this operation only on-time at manufacturing production of the boards and then save the values to be used during the whole application life, in general at Manufacturing assembly of the MCUs the temperature is controlled, and we stay in Ambient Values not exceeding 30°C or let's say from  10 to 30°C.  

Hope it helps you

STOne-32.

[taste]

@STOne-32  This helps for sure, indeed during manufacturing we do have control over the temperature. If calibrating just once to adjust to the board specific characteristics is sufficient this is a workable procedure. We will also test if this works over th efull temperature range of our product.