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carrotIndustries / pluto

Pluto is a programmable digital watch that re-uses case and LCD panel of the Casio® F-91W. (Hardware)
GNU General Public License v3.0
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why no sub-optimal 1 GHz antenna? #3

Open hackrid opened 8 years ago

hackrid commented 8 years ago

even if no long distances could be reached, wouldn't this be a good feature?

it would also free up board space for a barometric pressure sensor. the watch housing is not hermetic which should make pressure sensing inside the housing possible. not ?

carrotIndustries commented 8 years ago

I guess you're thinking of the the CC430 MCUs? We've thought of them as well, but couldn't find a suitable antenna. Since I've got no experience in designing antennas, the only choice would have been a chip antenna. All of these were way too large to fit inside the plastic frame. Aside from the antenna, the RF part requires an extra crystal, extensive decoupling and a balun.

The ez430 Chronos at least has a special rubber dome above the pressure sensor, so I guessed that a pressure sensor doesn't work through the rubber seal on the back of the watch.

hackrid commented 8 years ago

your right, the crystal and the balun might be a show stopper.

I'm no RF expert, but even a really bad antenna design might work for a few meters.

the ez430 Chronos is "30m water resistant" which makes it more hermetic and thus might need a membrane for the pressure sensor.

hackrid commented 8 years ago

what are your thoughts regarding NFC?