If you want to access all of the features on your computer's serial port, this serial adapter is for you. The adapter allows you to connect your 3-5.5 V logic circuits to a serial COM port, which operates on higher and negative voltages (EIA-232, similar to the older RS-232 standard). The adapter is available fully assembled with male header pins facing down for use with prototyping boards and breadboards.

This adapter distinguishes itself from most competing units through its five drivers and three receivers, which give you access to all eight signal lines on a DB9 connector. This means that in addition to standard serial communication, your project can also use all of the handshaking lines and status lines. Even if you do not use them for their intended purposes, you might find it convenient to be able to reset your processor using one of the extra lines. A connection detection line gives your project additional options for responding to a physical connection to a serial port. All of this connectivity comes in a compact package that is less than twice the size of the DB9 connector alone.

The first nine pins on the deluxe serial adapter correspond to the same nine pins on a COM port DB9 connector. The additional pins are the logic supply voltage, the serial connection detection pin, and an inverted version of the transmit line (which can be useful if, for instance, you have a positive-edge triggered interrupt that you want to fire in response to the beginning of the start bit). The TX line and RX lines are labeled from the computer's perspective, so the TX pin has data transmitted by the computer that should be connected to your project's receive input.

Dec 8, 2011 Update: We are now shipping a new revision of this serial adapter featuring a built-in power capacitor that makes this part less susceptible to damage from destructive LC voltage spikes. These new revisions are more robust drop-in replacements for the previous adapter version (they have the same dimensions, pin-out, and functionality).