Hi! I am working on a design that uses an SD card and an STM32U5 MCU. In trying to educate myself more thoroughly about SDIO bus design, I've come across LVS (low voltage signaling), which is part of the UHS-I spec and required for reaching SD speeds above 25MB/s.
I've not designed for this before, and an interested in examples that demonstrate the level-shifting part of this. I'd be particularly interested in solutions that allow the MCU to run at 3.3V, rather than 1.8V, though it's possible that this is an unusual thing to want (I'm still fairly ignorant about this...but keen to learn!)
I'm wondering, then, if there are any ST eval boards that demonstrate this in any form? I found this forum post that suggests a few solutions, but most rely on the MCU being run at 1.8V.
(I am further aware of the notion that some MCU's have a VDDIO domain that allows the MCU to run at 3.3V but allow some peripheral to be run at a different/lower voltage. Unfortunately the U5 series uses this domain on pins PG[1:15], and none of these pins include the SDIO/SDMMC peripherals, so I cannot use this approach unfortunately).
Thanks so much!
