Ethernet design requirement with STM32H755

[MK.111]

Dear Experts,

We have a design with STM32H755 having 3 Ethernet ports. Out of which 1 is over RMII controller the other two are over SPI interface.

My queries are as follows,

1. We want to run all 3 three Ethernets at the same time, How to handle this software?

2. Can LwIP handle the 3 Ethernets stack at the same time?

3. Any suggestions to breakout and utilize both cores (M7, M4) at the same time?

4. Any suggestions for the Ethernet to SPI controllers which can be interfaced with this chip?

I'm hoping to get better inputs from the experts as I'm new to this platform.

Thanks

[Tesla DeLorean]

The platform is likely to get swamped.

This type of implementation typically uses an Embedded Linux Platform.

A secondary alternative would be to use a programmable switch, managed by the STM32

As the complexity rises you probably want to consider commercial TCP/IP stacks. Something with some rigor would be needed for military, aerospace or health applications. Green Hills Software offer a particularly robust implementation.

[Pavel A.]

1. Like having any other peripherals work at the same time. This is exactly your job to design.
2. Yes. LwIP supports multiple interfaces.
3. Perhaps one core will be able to manage all interfaces (with proper design), LwIP running on this core as well.
4. With a multiport switch such as Microchip KZ series, you can operate all three ports over the built-in ethernet controller alone. These switches can send a packet out of specific port and redirect incoming packets from all ports to the controller.

--pa

[MK.111]

Hi Tesla DeLorean,

Glad to see your quick inputs.

1. Does this chipset supports Embedded Linux or FreeRTOS? Any reference or helpful links please?

2. The requirement is to realise the Ethernet one with RMII and other 2 with SPI interface. So the managed switch is eliminated here.

-Thanks​

[MK.111]

Hi Pavel A,

Glad to see your quick inputs.

1. My doubt is about which platform supports this? Freertos or Embedded Linux or any?

4. The requirement is to realise the Ethernet one with RMII and other 2 with SPI interface. So the managed switch is eliminated here. Any Ethernet to SPI chips which can be ported on STM32H755?

-Thanks​

[Tesla DeLorean]

SPI functions in materially the same way on STM32 as anywhere else. You'll just need to port the driver code, and tune the hardware interfacing code to use the STM32 peripheral implementation.

[Tesla DeLorean]

The STM32MP1 is ST's Embedded Linux platform.

The H7 could probably run uCLinux, although I'm generally of the opinion this is a half-baked approach, and running full Embedded Linux on an appropriate platform, with an active development community and team is the way to go, everything else is a heavy lift.

[Pavel A.]

> So the managed switch is eliminated here.

Some KZ switches have SPI interfaces. But it is your choice. Well, use a SPI part such as Wiznet or Microchip.

> Freertos or Embedded Linux or any?

As "Tesla DeLorean" wrote, H7 cannot run a normal Linux, so - either FreeRTOS or other RTOS of this sort.

Would you like advise on challenging and declining unreasonable requirements?

  

--pa

[Tesla DeLorean]

>>So the managed switch is eliminated here.

Was thinking a board/chip level implementation, rather than external. There have to be SoC solutions that have a better fit than cramming down packets on a STM32H7 at wire speeds.

[Tesla DeLorean]

>>The requirement is to realise the Ethernet one with RMII and other 2 with SPI interface.

Yeah, I think going back to the brainstorming stage would be advisable if you haven't designed it yet. There seems to be "We could do it this way" without a "Should we do it this way" conversation. There are companies whose entire business is around SoC, Linux/MPU, network switching IP solutions, and ST is not one of the names in that domain.