The ConnectCore 8M Nano platform uses U-Boot (Universal Bootloader) as its primary bootloader. U-Boot is an open-source project. You can find standard documentation about commands, environment variables, Flattened Device Tree support, and more at

About this guide

This guide only describes specific changes made to the standard U-Boot by Digi International.


U-Boot for ConnectCore 8M Nano is based on standard U-Boot v2020.04 plus NXP patches at

Supported interfaces

The U-Boot for ConnectCore 8M Nano supports the following interfaces:

  • UART1 for console (115200/8/N/1)

  • LPDDR4

  • eMMC for storage (on USDHC3)

  • uSD card (on USDHC2)

  • 10/100/1000Mbps Ethernet on Atheros AR8031 PHY (RGMII)

  • I2C multi-port

  • One-Time-Programmable (OTP) bits

  • USB device for Fastboot communication

U-Boot has not fully implemented device tree support. Although U-Boot source code contains a device tree, not all drivers make use of this information. Changes you make to the U-Boot device tree may not have any effect if the modified nodes and properties are not supported by their corresponding drivers.

Fastboot support

Fastboot protocol is a mechanism for communicating with bootloaders over USB. It is designed to be used across a wide range of devices and from hosts running different operating systems.

Fastboot enables you to boot and control your device, including:

  • Running any U-Boot command on the target from your host machine

  • Downloading images and files directly into RAM

  • Programming and erasing entire partitions from eMMC

To start Fastboot on your device, run the fastboot command:

=> fastboot <USB interface>

This leaves the device awaiting communication from the host through the selected USB interface. You can use UUU NXP tool in your host machine to communicate with the device.

See the UUU release repository for additional Fastboot documentation.

Carrier board version and ID

Digi uses non-volatile media to store the carrier board version and ID. See Carrier board version and ID.