External RAM for NUCLEO-H753ZI

[Clod]

Hi everyone,

I'm working on a project using NASA's Core Flight System (cFS) running over RTEMS RTOS, and I need approximately 8MB or more of external RAM for the workspace/heap.

Currently, I'm using a NUCLEO-H753ZI board (STM32H753ZI), which only has 1MB of internal SRAM. I've been looking for an easy way to add external RAM, but I'm running into some challenges.

My questions:

1. Is there an easy way to add 8MB+ of external RAM to the NUCLEO-H753ZI?

   • I've looked into FMC-based SDRAM shields/expansion boards, but I haven't found any off-the-shelf solutions that work well with this board.

   • Is there a shield, module, or expansion board I should know about?

2. If adding RAM to this board is not practical, which STM32 board would you recommend instead?

   • I need: 8MB+ RAM, Cortex-M7 (or similar performance), and preferably existing RTEMS/cFS support.

   • I've seen mentions of STM32H745I-DISCO or STM32H747I-DISCO having onboard SDRAM, but I'd like community input on the best choice.

My stack:

• OS: RTEMS 6.1

• Framework: NASA cFS (Core Flight System)

• Requirements: ~8MB heap/workspace for cFS tasks and buffers

What I'm looking for:

• A development board that's ready to use (onboard external RAM, not requiring custom PCB design)

• Ideally maintains STM32H7 architecture (for compatibility with my current toolchain/drivers)

• Good community support and existing BSP/drivers

Any suggestions or recommendations would be greatly appreciated!

Thanks in advance,

                    Claudio

[Chris21]

Apparently there exists a board referred to as  STM32H753I-EVAL2 with lots of RAM.  Does not appear to be in stock at the moment, though.

[Chris21]

Maybe you could use: https://www.st.com/en/evaluation-tools/stm32h757i-eval.html ?

 

[Clod]

Greati nput! Thanks a lot!

[mƎALLEm]

Hello ​@Clod and welcome to the ST community,

To my knowledge there is no available RAM extention shield for that board but (as you said) I recommend to use the available ST boards such as STM32H745I-DISCO or STM32H747I-DISCO. The hardware was exhaustively tested and alidated.

Adding an SDRAM is not an easy task. You need to ensure the signal integrity, otherwise you will face data corruption and communication issues with the external memory.

For more details:

AN4803 “High-speed SI simulations using IBIS and board-level simulations using HyperLynx® SI on STM32 MCUs and MPUs”

How to avoid signal integrity issues on the STM32H7R7/S7

Hope that helps.

[Clod]

REally useful feedback. I appreciate!

[Pavel A.]

In addition to the previous reply: the main interface for adding SDRAM is FMC.

It allows adding a lot of RAM but requires many pins and careful board work (not any Nucleo with a breadboard).

OSPI/XSPI memories need less pins but are slower.

The DISCO boards have several external memories so you can try and decide.

 

[Clod]

Thanks!!!

[LCE]

I recommend the H735-DK (H735 is a single-M7 core MCU with up to ~500 MHz or so), it has a HyperRam / OCTOSPI chip with 16 MB, and in memory mapped mode this works with about >= 50 MB/s write and read times.

[Clod]

I'll take a close look. Thanks a lot!