This cable is a USB to Serial (TTL level) converter cable. Identical functionally to the FTDI cable, it is one of the easiest ways to connect a TTL interface device to USB and fits directly to many boards.
The cable uses FTDI's FT232R chip, which is powerful and well documented. The device is housed inside the USB 'A' connector and is terminated at the end of a 1.8m cable with a 0.1" pitch header socket which provides access to transmit (Tx), receive (Rx), RTS# and CTS#. These lines all operate at 3.3V levels. Also brought out on the header are VCC (5V) and GND.
FTDI's royalty-free VCP drivers allow for communication as a standard COM port and D2XX ‘direct' drivers provide DLL application programming interface. UART interface support for 7 or 8 data bits, 1 or 2 stop bits and odd/even/mark/space/ no parity. 3.3V CMOS drive outputs and 5V safe TTL inputs makes the TTL-232R easy to interface to 3.3V devices.
