Lack of other 4GB RAM alternatives for MP25x

[DMårt]

Due to the high cost of RAM. I wonder if ST have plans or other information about which 4GB RAM vendors fits MP25x products?

I know that ST have information about other RAM vendors on their wiki. Only one 4GB vendor is mention there.

I bought the 4GB RAM MT53E1G32D2FW-046 WT:C (single rank) from here when it cost 20 USD.

https://www.aliexpress.com/item/1005009146059053.html but its seems to only having the DDR density to 8bits (2 GB). Perhaps it was only a 2GB or MT53E1G32D2FW-046 WT:B (dual rank)

I'm still looking for other RAM vendors that can offer 4GB solutions for the MP25x. 

Question:

Can ST write a criteria what a RAM memory need to have to fit MP25x? Do the RAM need to follow a specific RAM standard? What do I need to know to know if the RAM memory fits the MP25x?

[Erwan SZYMANSKI]

Hello @DMårt ,
Maybe this Application Note could help you to get DDR criteria accepted for STM32MP2x designs: https://www.st.com/resource/en/application_note/an5723-guidelines-for-ddr-configuration-on-stm32mp2-mpus-stmicroelectronics.pdf

Kind regards,
Erwan.

[DMårt]

Thank you @Erwan SZYMANSKI for the reply.

So, dual channel e.g MT53E1G32D2FW-046 WT:B can work with MP25x?

If a RAM follows JEDEC standard, it's compatible with MP25x?

[PatrickF]

Hi,

maybe a mixed-up with dual-channel (STM32MP25 has 2 x 16bits channels in lockstep mode to form a 32 bits memory) and dual-rank (2 x chip select per channel, which is not supported by STM32MP25).

The MT53E1G32D2FW-046 WT:B (dual channel, dual rank per channel) could work with STM32MP25, but with half of the size accessible (i.e. 16Gbits).

The MT53E1G32D2FW-046 WT:C (dual channel, single rank per channel) will work with STM32MP25, with full size accessible (i.e. 32Gbits).

Regards.

[PatrickF]

To check which memory you get, you could use https://www.micron.com/sales-support/design-tools/fbga-parts-decoder 

On my STM32MP257F-DK, it is a 'D8DVT'

Regards.

[PatrickF · Accepted solution]

Hi,

Btw, did you look to use 2 x DDR4 16-bits 16Gbits (as on STM32MP257F-EV1) ?
Might offer more manufacturer choices and so lower price or better availability (LPDDR4 32-Gbits single-rank is almost limited to Micron as far as I know).

Furthermore, DDR4 timings are usually slightly more robust than LPDDR4 (at the expense of more power rails and PCB terminations).

Regards.

[DMårt]

Thank you! @PatrickF 

According to the rammemory, it's a M-logo and it's standing D8DVT onto the chip.

So I guess it's a copy from real china factory then.

Anyway! It's seems to work with 2 Gb density.

[DMårt]

Thank you @PatrickF ! I did not know that!

By the way! I think you should try Kingstons memories. They seems to be single rank and 32-bit density.

I will look at DDR4! Perhaps it might be a 4 GB DDR4 that fits my board.

Edit:

I look up the prices for DDR4...more expencive than LPDDR4! And only 16-bit density size.

So I'm staying at LPDDR4! 

The Kingston B3221PM3BDx might look interesting!

[PatrickF]

You should try to ask Kingston directly, seems they could be OK.
Sometimes memory manufacturers make their own tests and publish results (e.g. here).

For our DK and EV boards, we will probably not change as there is long term agreement with Micron (which allow us to sell boards at decent price).

Regards.

[DMårt]

@PatrickF @Erwan SZYMANSKI 

I have notice that there is a much lower price on dual rank memories that have the same footprint as the C-version.

Is it possible to re-route the tracks so it fitt fully 4GB of dual rank memories. Or is it a specific strategy that DK boards is using single rank? Perhaps lack of pins ?