SPI mode and UHS-II mode not supported for STM32U5xx

[broilmont]

Hello,

I have  a very basic question. In the spec of the U5 series there is this:

Does that really mean that the U5 would not support talking to an SD card in SPI mode? I find it hard to believe since SPI seems to be the most basic way to interface with an SD card.

[AScha.3]

why you want use spi for sd-card, when you can have much faster sdmmc access ?

you can use spi, but this is up to you; and you have to write the low level access yourself.

its not supported by the HAL libs.

[Mike_ST · Accepted solution]

Hello,

I guess they wanted to say that the SPI mode is not supported through the SDMMC block.

You have to use a dedicated SPI block instead.

[Tesla DeLorean]

Pretty sure it supports a basic 1-bit mode at initial and normal clock rates.

What might not work are really antiquated MMC cards from before the dawn of time. Assumption that you have SD, SDHC, SDXC cards or eMMC device that will clock at 25 or 50 MHz out of the gate.

Full Size 128MB cards? who cares at this point?

Pretty sure it could do 8-bit MMC +Plus cards if you could find a socket in current production.

Only has a transceiver on SDMMC1, up to 4-bit on SDMMC2

eMMC typically doesn't need a transceiver

[broilmont]

I think this makes the most sense. The Simplified specs v6 states:

I'm guessing it's simply restating this, since in the older L4 series we have:

Anyways, it's not so much important I just found the sentence curious. I believe SPI mode can still be useful in some applications where we don't have access to numerous pins.