SparkFun Thing Plus Dual-Port Logging Shield allows accessing the microSD card over both SPI and USB-C. This board is designed to be mounted on or under one of the Thing Plus boards. An ATtiny841 microcontroller on this board acts as an arbiter that automatically puts the Dual-Port Logging shield into SPI mode. ATtiny841 will put the shield into SDIO "thumb drive" mode. The Arduino code can access the microSD card normally by powering the shield from the computer and connecting it via USB-C. Data can be logged and read from the microSD card over SPI using the Arduino SD library. This dual port logging shield features footprint and breakout pins, a USB2241 ultra-fast USB 2.0 media controller, and a push-push microSD socket. The logging shield is ideally used in power source voltage sensing and power LED (configurable).