AVR Freaks

Yesterday I had received the visit of Atmel's sales man, and he told me that the 'official announcement' will be next monday. They plan to begin with LCD AVR's then extent to all of the family in the next months, including ATmega64P, ATmega128P, ATmega16P...

Promising, but with many more registers to play with to control power: shut off totaly the digital inputs, sleeping BOD, "zero power" RTC, new sleep modes, new wake up options, down to 0.6 or even 0.4 nA. at 1V8, etc.

Alkaline cell manufacturer's wouldn't be happy.

Guillem.

> Is it possible to run a V chip with a 32kHz oscillator at a 'sleep'
> mode with less than 1uA?

That should be possible, yes. Usually, you'll run the AVR on a higher
clock though while it is awake, and use the asynchronous timer to wake
it up between sleeps. The integral power consumption ought to be the
same (as while you are awake, you get the job done proportionally
faster), assuming you can use the internal RC oscillator for the main
clock so you don't have any startup delays. (Crystals oscillators
tend to stabilize very slowly, so you'd require a larger startup delay
for them, consuming power without really using it to compute
something.)

I did something similar (just for a test) with an STK504, that's the
new LCD starter kit, running an ATmega3290. I can't tell you for sure
anymore (I didn't record the measurement anywhere), but I think I got
the current consumption *including* the LCD well under 100 µA. The
scenario was basically the same, the 32 kHz timer (which is connected
to the LCD controller there) woke up the chip every once in a while.
Keep in mind that most of the current was needed to recharge the LCD
segments, and that the wake-up rate is related to the LCD frame rate,
so it's much higher than once per second. Given that, I think you can
already get into the 1 µA range without one of those `picopower'
devices right now.

What I did, however was to aggressively turn off everything inside the
AVR that was not needed for the job. Modern AVRs allow you to turn
off the clocking of various subsystems internally, thus conserving
more energy.