AVR-Chat

Does the 8-bit AVR (e.g. ATMega88PA) have a means to sense the removal of
power and to execute 

a save-state operation to EEPROM before the supply voltage drops below the
critical level necessary

to change the EEPROM?

 

I am using an on-board regulator to supply 5 volts to the AVR.  The
regulator has 200 msec or more of hold-up time after power is removed.

 

I could certainly add hardware to allow sensing a drop in Vcc below, say, 4
volts, which could be used to trigger the save-state operation.

 

But I would like to avoid adding hardware.

 

I am using an ADC input to the AVR to sense a thermistor voltage.  That
voltage does not change very quickly.

 

However, a drop in Vcc would immediately be reflected as a drop in the
thermistor voltage and, providing that the 

AVR was still alive, the save-state operation might work.

 

Any ideas?

 

Thanks,

 

Benny Smith

Inchworm Solutions LLC

Santa Rosa, CA



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