This AVR Sensor Board V3 node has been built using a different voltage regulator, together with modified values for the battery sense resistor divider, to allow it to be powered directly by the car battery. It has a bi-directional serial connection to the existing car PC and zombie mode is entered (by sensing the 5V supply from the USB serial lead via a resistor divider) when the PC is not running.
The node operates as a car battery voltage sensor regardless of zombie mode.
When not in zombie mode the node enables the RFM69 receiver and the serial connection to the PC. This allows the following features:
The car PC based APRS tracker is modified so that whenever it transmits an APRS position update it also sends a suitably formatted location string on the serial connection to the UKHASnet node. The node software then transmits this string as the payload of a UKHASnet format packet.