Frequently Asked Questions

Documentation Help

General help regarding this documentation can be found in Documentation Help.

General Questions

Connecting TTL Terminal

How to connect a terminal to your module see TTL Converter Terminal Connection.

Enabling USB Bootmode

For instructions on how to enable the USB (Serial Downloader) boot mode on your module, please refer to: Enabling USB-Bootmode.

Select Function of USBOTG port

The function of the USBOTG port can be selected via the U-Boot environment variable otg_mode.

Variable setting

USB port function


USB host port (for connecting USB devices like memory sticks or ethernet/serial converters)



USB device port (for using the module as a USB gadget)

none (or empty)

USBOTG port deactivated

The setting of this variable does not affect the Serial Downloader mode.


setenv otg_mode host

Updating Single Files

How to update single or multiple files on our modules without re-flashing the whole module see Updating Files.

UUU on Windows 7

If you want to run uuu on a Windows 7 host have a look at Running UUU on Windows 7.


UUU USB Failures

If you’re experiencing USB connection failures with uuu see UUU USB Failures.

Compile Errors on Modern Kernel

If you have compile errors on a Host-System with modern Kernel (>=5.4) see Compile errors with modern Kernel on Host.

Requested init /linuxrc failed

Use init=/sbin/init on the Kernel Commandline.