General • Re: What percentage of MicroSD card supports SPI and FatFS

I certainly can't imagine a situation where I would use a 2TB+ SD card in Pico

Incidentally, the FatFs library also supports ExFat as an option, so this should not be a problem. However, the user-added SD card driver part must handle the SD card type appropriately. For example, older SD cards (<2GB) are addressed in bytes, while SDHC cards (<32GB) and SDXC cards (<2TB) need to be switched to 512-byte units. In addition, to handle the entire area on SD cards of 4 GB or more, the address needs to be managed in a variable type of 32 bits or more.

I was looking at what I could get my hands on from the Simplified version SD Memory Card Specifications Physical layer specification Version 1.01 (April 2001!) in order, and the changes in description are a bit fun.

The SPI compatible communication mode of the SD Memory Card is designed to communicate with a SPI channel, commonly found in various microcontrollers in market.
(Version 1.01, April 15 ,2001)

The SPI mode consists of a secondary communication protocol that is offered by Flash-based SD Memory Cards. This mode is a subset of the SD Memory Card protocol, designed to communicate with a SPI channel, found in some microcontrollers.
(Version 9.10, December 1, 2023 )

SPI Mode support for SD cards (excluding SDUC cards) should not be a problem; it could be a question of whether the SD card driver software handles the differences between SD cards correctly.

Statistics: Posted by 0yama — Wed Jul 10, 2024 1:37 pm

---