There are two versions of the JARVAS hardware: a base station board that supports WiFi (using an ESP8266 ) and is designed for easy debugging, and a small, low-cost tag module. The system requires at least one of the anchors have WiFi support so transmit location data to a server, however all other anchors and tags in the system may use either the larger base station board or the small tag board.
The tag board hosts an Atmega32U4, a single-cell LiPo/Li-Ion connector, a few debugging LEDs, and the DWM1000 radio module. It is essentially a purpose-built version of the popular SparkFun Pro Micro or the Adafruit Atmega32U4 breakout with a DWM1000 module built in.
In total, it measures 1.5"x0.9" without the programming tag.
Note that while we call this this "tag", it is completely capable of being used as an anchor as well, provided that there is at least one anchor in the system which supports WiFi.
The tag comes with a break-away section for initial programming. The section at the top contains test points for the 3.3 V and GND rails and an ICSP header. This ICSP header can be used to program the Atmega32U4. If you choose to install the Arduino firmware, as described here, you can program this board directly over USB through the Arduino software. Once you verify that everythings is working, this top section can be broken off to reduce the size and height of the PCB.
The anchor is the larger, more debug-friendly, and WiFi-supporting version. It is extremely similar to the tag except for the addition of an ESP8266 WiFi Module and using an off-the-shelf Arduino Pro Micro instead of having an Atmega32U4 on-board. This means that no programmer is required to get this board up and running. The downside, though, is that it is significantly larger and costs more.