I have a project that will run inside a vehicle that checks the temperature every minute and takes action based on it. The device will sleep for 5 minutes, wake up for a second, and go back to sleep, to maximize battery life. The settings will be stored in either a micro SD card or an EEPROM IC.
I wanted to make a separate "controller" Arduino that will have a Bluetooth interface that will only be powered when the vehicle is on, to make changes to the settings.
Is there any way to connect both Arduino's to the same EEPROM chip or SD card reader? I could hook up the two Arduino's together over Serial, but since the controller doesn't know when the primary board will be awake, it will constantly be sending an "update" command without knowing if it was received. It's like asynchronous information sharing, which is why I thought having a shared/common data storage would make the most sense if it was doable.