ANN: Freerunner Navigation Board v2

Al Johnson openmoko at
Thu Jun 17 00:43:17 CEST 2010

On Wednesday 16 June 2010, Christoph Mair wrote:
> Hi all!
> Thanks to a new triaxial gyroscope chip which became available a few weeks
>  ago I started to work on a new navigation board for the freerunner. The
>  new chip reduces the complexity which results in a single layer board
>  containing the triaxial gyroscope ITG3200, the triaxial compass HMC5843,
>  and the pressure sensor BMP085 and about seven passive components.

Nice. I had been looking at the L3G4200D with similar things in mind, but it's 
not available yet. Perhaps I should have asked about samples.

> The layout is done a final test is still pending. All drivers are tested
>  and they work.
> Currently I'm waiting for a quote about how much it would cost to assemble
>  the boards. It should be possible to get the assembled boards including
>  all costs for components, PCB and assembling for about 75€ to 80€.
> If there is enough interest I'll try to get a first "production run" done.
> Since the backside of the board is still empty, the new navigation board
>  won't replace the same amount of embedded air as the first version did.
>  Any ideas on how to fix this 'design flaw'? I'm proposing the SHT21 a
>  digital humidity sensor (from which I have a working sample) but the
>  general availability is still limited.
> The price difference between a single and a dual layer board is negligible,
> therefore it's possible to include at least a footprint for new hardware,
>  or simply a lot of solder pads for easier expansion. Suggestions?

You had the option of an ambient light sensor using the spare adc channel on 
the first board.  That sensor would still be useful.

An ear proximity sensor might be handy. A capacitive sensing element using 
conductive paint on the inside of the case might do the job. Come to think of 
it, with a multichannel sensor ic we could use the sides of the case as a 
slider or a chording keyboard.

An ANT transceiver might be nice, but I don't think they're small enough for 
that space.

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