STM32H7S7L8H6H Unable to use Ethernet (RMII) and SDMMC2 at the same time?

[sk-st]

Hello,

i try to configure a STM32H7S7L8H6H in CubeMX and it seems that, when Ethernet RMII is configured, SDMMC2 is unusable because there are some pins like PC1 which can't be remapped. Can this be true?

This chip is designed for external memories and i want to use microSD and eMMC.

What is the STM32H7S7L8H6HU chip? Is it a improved stepping?

[AScha.3]

Hi,

we talking about STM32H7S78-DK - right ? or making new board ?

There is SDMMC1 connected , you can use for microSD .

>Can this be true?

Yes, if you cannot remap to other pin, because this has already other function you want - this combination not possible then. Maybe you can remap this occupied pin to other pin, then use for the function , that you cannot remap to other.

But for sure - not all combinations of alternative use of pins are possible - that's life . 

+ about PC1 : seems, you can use PB2 for RMII :

+

btw

You know, Cube can show you, what remaps are possible for a pin ?

Just in CubeMX (in view of cpu outline) : press + hold Strg (Ctrl) on keyboard, then click mouse on a pin -> all possible remap positions blinking then.  Helps a lot, to find possible remap combinations.

[sk-st]

I found a solution but CubeMX has some pitfalls.

When a pin is relocated, let's say from ETH and ETH is then disabled, the relocated pins are still allocated/not available for other functions.

[sk-st]

STM32H7S7L8 can't use SDMMC2 together with LTDC/RGB and Ethernet (RMII).

This is because SDMMC2_CMD can be routed to:

- PA0 but this is needed for LCD_G3 which can't be relocated.

- PD7 but this is needed for ETH_RMII_REF_CLK.which can't be relocated.

As well with the signals SDMMC2_D2 and SDMMC2_D3.

It seems that STMicroelectronics did not have a usecase for

- LTDC RGB

- ETH RMII

- SDMMC1 SD

- SDMMC2 eMMC

with the BGA225 Package when designing the GPIO AF routing.