The Compass Board is a small board containing the HMC5883 3-axis compass module by Honewell. The chip can be configured to 8 different sensitivities, from 0.9 to 8 Gauss full-scale, with read-outs up to 160 times per second. There is a “CompassBoard” class in the JeeLib library to interface with this sensor and read out all three on-board compass axes.
This board uses an I2C bus running at 3.3V as interconnect. There is room for a Port-compatible 6-pin header and there's a 4-pin header on the other side which can be used to tie the Compass Board to an RBBB, Arduino, or similar, running at 5V. This is possible because the board also contains a 3.3V regulator and level converters. Note that unlike most "JeePlugs", there is no second 6-pin headers, so physically daisy-chaining it with other I2C modules is only possible by connecting it in parallel, or placing it at the end of the chain.
The Pre-assembled version comes with the SMD-sized HMC5883 chip and other supporting components already soldered onto the board. Note that no 6-pin headers are included.
As connectors you can use a Plug Headers set with 10 male and 10 female 6-pin headers, which makes it easy to connect multiple plugs and JeeNodes in a “standard” way. Or you can solder the board directly in place for more permanent use.
Note: this new Compass Board replaces the Heading Board, which is no longer available.