anelok: first light

Werner Almesberger werner at almesberger.net
Tue Sep 24 12:28:46 EDT 2013


Felix wrote:
> Awesome!! From idea to some kind of prototype in less than 2 weeks!!

Well, there's still a lot missing ;-)

> Btw, I don't how well will handle a cr2032 a current of almost 10ma;

10 mA is just the display. There's also MCU, memory card, and
possibly RF. Most of them have low duty cycles, though.

> I know
> the lcd only will be on for sort period of time (~2min?),

2 minutes is quite a lot. I don't think you'd want to spend more
than a minute on entering a password. Probably a lot less.

> but it'll
> interesting to know what life battery cand we expect with this consumption.

I did a first estimate a while ago:
http://lists.en.qi-hardware.com/pipermail/discussion/2013-September/010189.html

> Say for example, the screen is on 10 times a day for 2 minutes, with 210mah
> from a cr2032, and a sleep consumption of 0.1 mA we can expect:

I think we should be able to achieve a standby current < 10 uA.
The components that draw battery power directly are the MCU, RF,
and the boost converter. Each of them should be able to idle at
less than 1 uA.

> It's a bit low, no?

Well, with half the daily power consumption, I estimated about two
months of daily use on a battery. According to Amazon.com, a pack of
ten CR2032 should cost about USD 2-3 and would last almost two years.

- Werner



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