The Chronos is based on the CC430F6137, a sub-1GHz RF system-on-chip which directly controls the 96-segment LCD display. It is capable of beeping when buttons are pushed or sound an alarm and includes a backlight for use at night. The integrated wireless feature allows the Chronos to act as a central hub for nearby wireless sensors such as pedometers and heart rate monitors. It also includes a USB-based wireless Access Point to transfer data to a PC wirelessly. Chronos is available in three different frequency bands, 433, 868, and 915MHz, which allows it to work worldwide. Most US users will use the 915MHz version, European users will use the 868MHz version, and most other regions will use the 433MHz version. It is important to note that Chronos is a development tool and not an end product piece of equipment. Because it allows the user to modify the code running on the watch, it was not FCC certified. However, extensive hardware testing was done to make sure that it could pass FCC certification when loaded with the appropriate firmware. Real-time debugging and programming of the Chronos is possible using the eZ430 programmer. To use the programmer with the Chronos, start by removing the inner electronics from the watch case and then connecting it to the programmer. It is also possible to load new programs wirelessly to the Chronos using the wireless update feature. The built-in sensors enable a great deal of the innovative features on the watch. First is the 3-axis accelerometer which makes it possible to track movement or to control an item based on the motion of the wrist. This functionality could be used similar to an RF game controller for basic gaming applications. There is also a pressure sensor that can accurately track altitude. The altitude can be logged directly to flash, which might be useful for tracking a skier’s descent down the mountain or to monitor free fall of a skydiver. Finally, the temperature and voltage sensors can also be used to provide information about the environment as well as the battery life. The temperature is a great approximation of the ambient temperature when the watch is not being worn. If the Chronos is worn, body temperature will impact the measurement and it will be somewhere between body temperature and the ambient temperature.