- I-Button reader (for ButtonImmobilizer)
- CourtesyLightController? (dimming interior light after you leave..)
- RealTimeClock? (nice to have real-time for datalogs)
- possibly other functions (???)
Can be bundled on a low power consumption board (that needs to be on all the time).
There is a good chance that RadioBoard (under desing now) will provide the hardware necessary for these function as well.
There must be some atmega just right for the job:
..... write your thoughts here ....
Atmel has a small board called the butterfly. It has an LCD display and is inexpensive. It would be just the thing for a dashboard display to give time, WB02 display etc.
Suggestion: 8 MHz Atmega128L, driven at 4 MHz, mostly sleeping, making his own 3..5 V from the battery with SW-driven switching regulation.
You need a PNP (from VBatt), an NPN (driving the PNP), 2 base resistors, a BE resistor for PNP, an LC and a flyback diode for the switching regulator. Around 100Hz you have enough time to measure and switch the transistors.. Also a 5.1V Zener parallel with C in case you get the program wrong :-)
Note: The atmega ADC can be made to measure it's own supply voltage...
why not have the 5.1V Zener go to the base of a NPN and have the NPN Emitter going to reset. That way if you go over voltage the system is reset and the switching stops. So bad code would just loop.