A question popped up on the Raspberry Pi forum a little while back asking whether the BUB could be used to connect to the serial port on the Raspberry Pi’s GPIO header. The answer is yes; it works quite well! The BUB is essentially a breakout board for FTDI’s FT232 chip that translates between a USB connection and a TTL-style UART. This is the chip that was on the pre-Uno Arduino (USB translation is handled in software on a second microcontroller on the Arduino Uno). The BUB (and BUB II) are used to communicate with most Modern Device and Jee Lab controllers, except for the BBLeo.
The BUB has a few other features that make it a bit more flexible than Just Another Breakout Board. For example there’s a polyfuse to help protect your computer if you accidentally draw too much current, and a jumper to change logic levels from 3.3 to 5 volts. The BUB I also has a handy breakout area that allows you to reroute the signals to any of the pins on the header. This is useful for connecting to devices with different pinouts like the Raspberry Pi or Parallax Propeller.