I like the idea of a micro with sram and eeprom inside and no external memory access for security.
I am designing a 5v system and wish to use the internal RTC and battery backup the rtc and sram, the battery is not a problem the swithc over circuit;
Does anyone know a more elegant circuit than 2 diodes ?
Also the voltage drop particularly to the cpu when running on 5v.
Does the AVCC have to be supplied during battery backup?
Exactly what needs to be disabled/switched off for minimum power consumption on battery power.
What are the traps, hints for lowest possible battery consumption.
The circuit will use the internal 8 ch A/D and I2c bit banged to one device and rs232.
Do the peripherals have to be isolated during power down? or is it just simply write a 0 to the port while running on battery? on the assumption that the rest of the circuitry is then at 0 volts.
Any help appreciated