Wiki » History » Version 4

« Previous - Version 4/6 (diff) - Next » - Current version
laforge, 07/22/2017 08:48 AM

multi-voltage dual USB UART

This is a CP2105 based dual-port USB UART.

As a very special feature, this device allows you to manually select the UART voltage levels to 1.8, 2.3, 2.5, 2.8, 3.0 or 3.3 Volts.

It is thus ideal for a lab environment, where you frequently need to interconnect with various embedded electronics devices that have UARTs at unusual voltages.

Both UART ports feature RxD/TxD/RTS/CTS signals and have TVS diodes for ESD protection.

Miscellaneous CP2105 GPIOs are available on a separate header


Annotated Pin-Out

annotated pin-out

ECI and SCI are the fancy names Silabs came up for the primary and secondary UART in their CP2105 chip.

Design Files / Schematics / Layout

The EAGLE design files for this open hardware project are available in the osmocom-small-hardware.git repository and can be checked out using
git clone git://

PDF renderings of schematics and component placement are attached below.

schematics rendered as png

Availability / Where to buy

The general idea of Open Hardware projects is that anyone is allowed to build the design. So feel free to take the design files and build it yourself, either modified or unmodified. Please make sure you always
  • attribute the original author (Attribution)
  • release any changes to the design files under the same terms (Share Alike)

A fully assembled circuit board can be obtained from

Add picture from clipboard (Maximum size: 48.8 MB)