The ConnectCore 6UL 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 6UL is based on standard U-Boot v2017.03 plus NXP patches at

Supported interfaces

The U-Boot for ConnectCore 6UL supports the following interfaces:

  • UART5 for console (115200/8/N/1)

  • DDR3

  • NAND Flash

  • uSD card (on USDHC2)

  • 10/100Mbps Ethernet on SMSC LAN8720 PHY (RMII)

  • I2C multi-port

  • One-Time-Programmable (OTP) bits

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.

Carrier board version and ID

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