A USB to UART adapter built around the CH340G controller. USB 2.0 compatible. Driver built into modern Linux operating systems (Ubuntu, Mint, Debian, ...) so should work out-of-the-box. All pins are broken out on a 10 pin IDC connector. Compatible with UEXT if you don't need SPI or I2C support. Full ESD and overload protection on all channels. On board 3.3V power supply, all output voltage levels are 0 - 3.3V. Voltage regulator able to supply up to 800 mA of current at 3.3V.
A self test application is available on the Github repository. Simply tie RXD and TXD together, then run the application to test it. The blue and white LEDs will flash. Requires Mono to run.
Update for Rev. 1.3: the LEDs are now flashing brighter (lowered resistors and swapped out TI buffer or a more powerful one). The TVS-diodes have also been changed to a type with lower capacitance, to support full speed USB. All modifications are pin compatible with Rev. 1.1 of the board.
Many thanks to Laurent Segers for the collaboration in this project!