GSoC 2008

Andy Green andy at
Tue Mar 25 11:54:13 CET 2008

Hash: SHA1

Somebody in the thread at some point said:
> Am Di  25. März 2008 schrieb Andy Green:
> [...]
>> It means that a perfect solution is predicated around
>>  - 16 bit integer arithmetic -- ha "no float" is too easy
>>  - per-sample short processing rather than large batching
>>  - multiply is expensive (but hey shifting is cheap :-) )
> Divide?
> Hey, for normalizing vector direction of gestures to different orientation of 
> NEO, we will need trigonometric calculations, no?
> Anyway, it shouldn't be much harder than trainable OCR of PALM (Tealscript?), 
> and i think we can compare the power of PalmCPU to that of MPU.
> If anything else fails, MPU has to buffer the G-meter data, and recognition of 
> the actual gesture has to be done on main CPU. (no real option)

Well it depends entirely on the algorithm and how smart we are.  If we
can bend the algorithm to use right shift instead of divide, or small
precomputed tables for the key actions, we can do it on a pretty weak

Ultimately the "gesture recognition" action is about eating 200 3-byte
packets of data a second and issuing only one or two bytes per second
about any "gesture" that was seen.  I guess one way or another we use
ringbuffers to keep averages of actions in each axis and try to match
that against templates.  Depending on the algorithm it can be the kind
of thing that can be done on a 16MHz MPU.

- -Andy
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