What sets the SparkFun Thing Plus Dual-Port Logging Shield apart is its ATtiny841 microcontroller. Acting as an arbiter, the ATtiny841 automatically switches the shield into SPI mode when you power up your Thing Plus. If you power the shield from your computer by connecting it via USB-C, the ATtiny841 will put the shield into SDIO "thumb drive" mode, allowing your computer to read and write data quickly. If you have both your Thing Plus powered up and your computer connected, you can switch between the two modes by giving the ATtiny841 some simple commands over I2C.
The ATtiny841 can also be configured to automatically default to SPI mode or SDIO "thumb drive" mode if both power sources are powered up simultaneously. This gives you full control over the mode of operation, ensuring flexibility and ease of use.
The USB2241, which provides the USB interface, supports FAT32, exFAT and NTFS on cards up to and including 32GB. Please note that cards larger than 32GB are not supported.
Key features of the SparkFun Thing Plus Dual-Port Logging Shield include a Thing Plus / Feather-compatible footprint and breakout pins, a push-push microSD socket, and a simple I2C command set to switch modes and set the default mode. The shield can be powered by Thing Plus / Feather 3.3V, USB-C 5V, or both. It also offers full power control, power source voltage sensing, an activity LED (for SDIO "thumb drive" mode), and a configurable power LED.
For further information, you can access the schematic, Eagle files, board dimensions, hookup guide, datasheet (USB224x), Thing+ Info Page, Arduino Library, and GitHub Hardware Repo.
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