We've looked at a fair number of USB-to-serial adapter boards, and even made one ourselves (but then the chipset went obsolete-sorry!). We've now found these DEV-09783 units by SparkFun to be quite nice. The brains of this board is the FTDI FT232RL in 3.3V configuration, a really solidly proven adapter chip, and SparkFun has packaged it into a nice and tidy bread-board friendly unit.

What makes this particular unit especially stand out is that it matches the function of the native FTDI USB Cable that is popular with Arduino users. Instead of having to get a whole bulky cable, add this adapter to a own USB-to-Mini-B cable for a less expensive and more flexible alternative! It also has blinky LEDs, which the FTDI cable doesn't have!

An important advantage with this board is that it brings out the DTR pin as opposed to the RTS pin of the FTDI cable. The DTR pin allows an Arduino target to auto-reset when a new Sketch is downloaded. This is a really nice feature to have and allows a sketch to be downloaded without having to hit the reset button. This board will auto reset any Arduino board that has the reset pin brought out to a 6-pin connector.

The adapter pins match the FTDI cable in that the pins labeled BLK and GRN match to the colored wires on the FTDI cable. The cable black wire GND, green is CTS. Use these BLK and GRN pins to align the FTDI basic board with your Arduino (or other microcontroller) board.

• [Support Software]: FTDI FT232RL Drivers (link)
• [Support Software]: FTClean (USB device port cleaner)
• [Data Sheet]: SparkFun FTDI Basic Breakout Board (3.3V)