Introduction

Note: due to an error in manufacturing, the first batch of these boards have no pinout on the silkscreen, so I am selling at a discount.

This is a board that breaks out two serial ports from a single USB connection. This is a smaller version of my Quad Serial Breakout.

It uses the FTDI FT2232H IC.

Often I have several serial devices plugged into my computer. Managing all those cables is a pain and each one takes up valuable USB ports (especially annoying on a laptop).

This board is meant to solve that problem.

Pinout and Interface

It provides a two 0.1" header strips for each of the ports. Each set of 2x 6-way header has:

5V, 3V3, TX, RX and 2x GND The full set of RS-232 control lines (RTS, CTS, DTR, DSR, DCD, RI)

All the RS-232 signals are at 3V3, but are 5V tolerant for easy interfacing.

Features

• 0.1" header pins on 0.2" row spacing designed for quick and easy cable management.
• TX and RX LEDs for those "is my thing working at all?!" moments.
• Open source hardware design.
• FTDI chipset for easy of use. Just plug in like any another USB-to-serial adapter.
• ESD protection device for USB data lines.
• Filtered chipset power supply increases resilience against EMI.

Loopback Feature

There are two solder jumpers on the board that allow connecting the TX and RX of UART1 to the RX and TX of UART2. This is helpful for testing of PC applications that rely on a serial connection - you can use one port for the application and one port to simulate your device.

This lets you test hard-to-reproduce scenarios, like hardware failures and other error conditions.

You can just do this by bridging the header pins with wires, but doing it with solder jumpers is much neater.

EEPROM

The underside of the PCB has pads for a 93C46 EEPROM that the FT2232 can use for alternative configurations and custom USB descriptors. This is left unpopulated, please select the option when buying if you want the EEPROM added.