More progress: the #RaspberryPi is now running the bridge software and communicating with the #Arduino Mega. The SD filesystem is read-only to prevent burnout and corruption in case of an unscheduled shutdown.
The Arduino, Raspberry Pi, and Teltonika TRM240 modem are drawing 660 mA at 5.11 V. The alarm cabinet now has 13.8 V with battery backup and 5 V from a DC/DC converter.
Next is to install this in the cabinet π