Which protocol to implement on a home brewed diving computer ?

[Robert Helling]

Hi,

> On 17.03.2015, at 11:33, Thomas Schrein (mailinglists) <tsx508 at schrein.de> wrote:
> 
> One option (may be you better say vision ;-) in our project is to use the odico electronics to control a rebreather using CANBUS (the controller has it build in already) and therefore the high pressure sensor would act as an CANBUS node with its own buildin controller, in particular a STMF1x, less then 5€ each.  The electronics could be sealed with casting resin.
> For our rebreather approach we accept the existence of wires, so we don't need to care about energy and communication. The pressure sensors cost about 80€, plus the adapter for the high pressure, plus the wiring, but that costs are not a big deal to run a rebreather.
> My fellow, Marco, also doesn't care to much building even an self made pressure sensor with build in electronics . He has a degree as mechanical engineer and he's really gifted for job!
> So we don't care too much to get it water tight.
> 
> From my point of view a logger could be designed like this:
> - located at the high pressure hole of the first stage
> - length about 5 - 10 cm, cylindrical
> - collecting data for pressure + time
> - as an option: collection depth+temp
> - energy by an AAA or 1/2 AA lithium 3v cell than could be replaced once a year
> - communication via radio (bluetooth, ...)
> - shop price < 200 €


80 Euros for the sensor sound like a good price. May I ask which sensor this is? When I did my research I found that you can buy sensors that already have the correct fitting to go into the HP port of a first stage (UNF 7/16”). For prototyping the logger I would have started with something like http://www.exp-tech.de/sparkfun-logomatic-v2-serial-sd-dataloger-fat32 <http://www.exp-tech.de/sparkfun-logomatic-v2-serial-sd-dataloger-fat32> That has everything including battery recharging logic (and is a USB mass storage device).

Best
Robert

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Robert C. Helling     Elite Master Course Theoretical and Mathematical Physics
                      Scientific Coordinator
                      Ludwig Maximilians Universitaet Muenchen, Dept. Physik
                      Phone: +49 89 2180-4523  Theresienstr. 39, rm. B339
                      http://www.atdotde.de

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