Internal pressure sensor

Stroller stroller at
Sun Oct 4 17:55:18 CEST 2009

On 4 Oct 2009, at 16:14, tom wrote:
>> > On Wed, Sep 30, 2009 at 06:04:30PM -0400, tom wrote:
>> >> actually i think they should already be built in...they are so
>> >> cheap...
>> >
>> >   Depends on what you mean when you say cheap. I see it listed at  
>> just
>> > under USD 10 for one sensor or the price of a 1.3 mpix camera
>> > module. It's
>> > also not as small as you would like for something you throw in
>> > mostly for
>> > fun.
>> Is the 1.3 mpix camera module also $10 for a single unit? That seems
>> remarkably good value.
>> One would expect a pressure sensor to be much cheaper on the 1000, of
>> course.
> well, my thought was just: marketshare. more features out of the box  
> > more customers > more competition.
> and i dont think 10$ make adifference, not yet talking about  
> largeqty-volumes.  eg rfid: nokia announces it since years, but FR  
> could be fo sorry, maybe im just to optimistic...

1) Please don't top-post in reply to a bottom-post. It makes the flow  
of the conversation difficult to read.

2) Please don't post to the list in HTML. Plain-text is preferable.

3) The costs of production were discussed a LOT on this list in the  
past, when the Openmoko team was still active. To be honest, even if  
the component is only $1 then it may be too expensive, as many more  
design and testing costs are added to the total production cost by the  
addition of the component.

Customers will be dissatisfied if it doesn't work as expected. A large  
increase in market share is needed to make the addition worthwhile.  
Therefore the addition of a camera may be worthwhile, whereas the  
addition of a barometric sensor is not.

However a camera requires retooling of the Freerunner's case, a  
surprisingly cost-prohibitive change. I think the cost of creating a  
new case for the Freerunner is considerably more than $10,000. I would  
imagine that a camera requires other components to make it work and is  
more complex from the design point of view. There have historically  
been two major complaints about the Freerunner - lack of a camera and  
of 3G. Either might enlarge its market share considerably, but both  
were rejected on cost grounds.

This barometer is self-contained and connected to the i2c bus, a  
_relatively_ simple addition. If there is demand for the barometer -  
although I'm inclined to agree with Rask that there wouldn't be - then  
it might it be justified to add it were Brazil ever to go into  
Freerunner production.

A 1.3mp camera would produce complaints that it's a poor specification  
compared to the iPhone. Hardly anyone would be grateful for the  
addition of the barometric sensor.

TBH, if the Freerunner were in reliable, long-term production, I might  
be able to imagine a market for Freerunners amongst hang-glider  
pilots. I think a person might be able to make a living adding  
Christoph's sensor and selling Freerunners with varioaltimeter  
software installed. The software would have to be closed-source,  
however, to make a livelihood out of it and realistically it might  
take a year to get the software to an acceptable quality for  
commercial sales (and still longer to build-up market share). The  
author might need to write anti-piracy measures into the code, and  
what is to prevent a determined attacker from patching the kernel to  
report a different IMEA number to the altimeter software?


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