Adafruit's Latest 512MB SPI Flash Part Is SD Card Technology on an SPI Breakout Board

A compact SPI breakout hides a clever secret: It presents itself as a Class 8 SD card, complete with auto-erase and wear-leveling.

Gareth Halfacree
4 years agoProductivity

Adafruit has announced the launch of a new breakout board packing 512MB of SPI-connected flash memory, but with a difference: It's a fully-functional SD card, compatible with any libraries designed for standard-format SD card storage.

"The breakout will act just like a 512MB sized card with FAT formatting (it’s pre-formatted)," the company explains of its latest release. "You might be wondering why you’d want such a thing — after all, you can’t plug it into a computer to get the files off like microSD cards. For some use cases, such as data logging in a high-vibration device where you don’t want the SD card to come loose, or for when you need to reduce size, or when the microcontroller provides a USB mass storage interface, this chip could very useful."

The compact breakout is based on a NAND memory chip and includes a controller which handles wear-leveling and error correcting code (ECC) internally, with no need to add such code to your project — nor to manually erase blocks before writing new data, as you would with a traditional SPI flash part. An included level shifter allows the part to work on 3.3V or 5V logic, while there's a 3.3V regulator and a pull-up resistor on the chip select pin.

According to the spec sheet, the part can be clocked up to 50MHz and is equivalent to an SD card Speed Class 8 for writes — however, Adafruit warns, you're unlikely to get maximum performance through a one-bit SPI interface when compared with a fully-wired SDIO interface.

The part is now available on Adafruit for $9.50 before volume discounts, and requires no additional code beyond existing libraries for communicating with standard SD card storage devices.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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