STM32L4Rxxx OctoSPI with PSRAM

[AlfaHotel]

Dear All,

In "RM0432 Reference manual STM32L4+ Series advanced Arm ® -based 32-bit MCUs" in chapter "19.3 OCTOSPI implementation" and table "Table 119. OCTOSPI implementation" there are some differences in supported features between families. All families support Xcella and Hyperbus. So i would think i can use PSRAM with some limitations, like ones that have Hyperbus differential clock.

But on presentation i have found (https://www.stmicroelectronics.com.cn/content/ccc/resource/training/technical/product_training/group0/38/14/f0/84/28/e0/4b/40/STM32L4Plus_Introduction_Delta_STM32L4_Series/files/STM32L4Plus_Introduction_Delta_STM32L4_Series.pdf/_jcr_content/translations/en.STM32L4Plus_Introduction_Delta_STM32L4_Series.pdf)

on page 26, it is mentioned for "External memory Quad/OctoSPI" that only STM32L4P5xx/4Q5xx families support those.

Question: wont any PSRAM memory work with L4R series? Why? What I am missing?

Thanks

[Peter BENSCH]

Welcome, @AlfaHotel​, to the community!

the errata sheet ES0393, section 2.8.22 of the STM32L4R mentions on this question:

PSRAM not supported

Some reference manual and data sheet revisions unduly mention PSRAM while this type of memory is not supported by the device. This is a documentation issue rather than a product limitation.

Does it answer your question?

Regards

/Peter

[AlfaHotel]

Hi Peter, thank you for the warm welcome and your reply :)

I am new to the modern SRAM's so my question might be naive, but please allow me to rephrase it:

If STM32L4R supports Xcella and Hyperbus interface specification, what stops it/me from using Xcella/Hyperbus-compilant PSRAM?

Is is something i can find in spec and maybe adapt to, or is it just some silicon-magic on chip design level and I cannot do anything with any PSRAM in the world?

Many thanks