The ArduinoTrack shield is designed to be used in one of two distinct modes. Originally designed as an Arduino Shield, the ArduinoTrack can used as such, but plugging it into the headers on a separate Arduino or Arduino clone board. In this mode of operation, the firmware file ArduinoTrack_Modem is installed onto the ArduinoTrack board, and the Atmel ATMega328p processor serves as a limited-functionality KISS modem capable of transmitting APRS.
In this scenario, the host Arduino would be programmed with the ArduinoTrack firmware file, and would handle the core logic to decode the GPS data stream, interface to any sensors such as the on-board BMP180 temperature/pressure sensor.
Alternatively, because the ArduinoTrack Shield has an Atmel ATMega328p processor embedded into the shield itself, it is possible to write a modified version of the firmware directly to the shield, and use it as a stand-alone tracking system. This configuration has the advantage of cutting weight and power consumption by roughly 50% over the stacked Arduino/ArduinoTrack Shield, while maintaining virtually all of its features. In this mode, the ArduinoTrack_Combined firmware is applied directly to the shield.
| Feature | Arduino/Shield | ArduinoTrack_Combined |
| Programmed and updated via easy-to-use Arduino IDE: | X | X |
| Simpler operation and programming: | X | |
| More available I/O pins: | X | |
| More CPU cycles and RAM available to customize firmware: | X | |
| Smaller and lighter: | X | |
| Less power consumption | X |
For use as a stand-alone APRS tracking beacon, most users opt to operate the ArduinoTrack in the _Combined mode, and consequently assembled ArduinoTrack kits that are sold by Custom Digital Services, LLC are pre-loaded with the _Combined firmware out-of-the-box.