Open Hardware Multi-Voltage USB UART board released

During the past 16 years I have been playing a lot with a variety of
embedded devices.

One of the most important tasks for debugging or analyzing embedded
devices is usually to get access to the serial console on the UART of
the device. That UART is often exposed at whatever logic level the main
CPU/SOC/uC is running on. For 5V and 3.3V that is easy, but for ever
more and more unusual voltages I always had to build a custom cable or a
custom level shifter.

In 2016, I finally couldn't resist any longer and built a multi-voltage
USB UART adapter.

This board exposes two UARTs at a user-selectable voltage of 1.8, 2.3,
2.5, 2.8, 3.0 or 3.3V. It can also use whatever other logic voltage
between 1.8 and 3.3V, if it can source a reference of that voltage from
the target embedded board.

Rather than just building one for myself, I released the design as open
hardware under CC-BY-SA license terms. Full schematics + PCB layout
design files are available. For more information see