Anelok: rework plan, battery update, left-shift, Anelok in China
Werner Almesberger
werner at almesberger.net
Sat Feb 14 13:35:08 UTC 2015
Just a few minor items for this week:
- I made a plan for reworking existing Anelok boards to make the
whole system run at 3.3 V:
http://downloads.qi-hardware.com/people/werner/anelok/tmp/boost-rework.pdf
More details:
https://gitorious.org/anelok/anelok/source/aeaccf8b538ae2f46c894dea5afe7037b7359ce6:doc/boost-rework/README
This looks reasonably simple. Losing the Vsys pad isn't nice but
not really a problem at this stage.
In the boost-rework branch, I changed the schematics and the layout
to reflect the modifications, and they still agree with each other.
I haven't actually implemented the rework yet, so there may still
be surprises, such as the idea not working at all.
- meanwhile, the battery is busy discharging and has just passed the
300 hours mark:
http://downloads.qi-hardware.com/people/werner/anelok/tmp/cr2032-300h.png
Not sure if the slight drop towards the end is a first sign of
weakness or whether this merely reflects the cooler weather of the
last couple of days. We'll see next week or so.
The effect of temperature is noteworthy. If we assume that the
difference between highs and lows is about 10 K, that would mean
a temperature coefficient of roughly 5 mV/K.
This may not seem like much but the voltage change caused by a
temperature difference of 10 K would then be the same as that
caused by a current difference of 2.5 mA or 20+/-10% of the
expected idle current (display on, LED off, not doing much else).
- items on the screen are now arranged in a more logical way in
left-handed mode. Here is an illustration:
http://downloads.qi-hardware.com/people/werner/anelok/tmp/handed.pdf
On top is the usual right-handed configuration. So far, switching
to left-handed simply rotated the entire screen content. This
caused the position marker (the little white blip) and the icon bar
to end up far from the finger, which looked a bit counter-intuitive.
The bottom drawing shows what it looks like now: position marker
and icon bar get moved to the left and the main display area starts
after them.
- last but not least, the folks at Canaan Creative (Xiangfu et al.)
have made a few Anelok boards. Some first impressions:
http://downloads.qi-hardware.com/people/xiangfu/anelok/tmp/brd-with-UBB-front.jpg
http://downloads.qi-hardware.com/people/xiangfu/anelok/tmp/brd-with-UBB-back.jpg
http://downloads.qi-hardware.com/people/xiangfu/anelok/tmp/Anelok-booting.jpg
Looking great ! Plus, it proves that the available design information
is sufficient to build working devices from it, i.e., that I didn't
hold back or simply forget something.
- Werner
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