Am 25.03.2015 um 14:18 schrieb Anton Lundin: > On 17 March, 2015 - Thomas Schrein (mailinglists) wrote: > >> >> >> Betreff: HighPressureLogger ... Re: Which protocol to implement on a home >> brewed diving computer ? >> Datum: Tue, 17 Mar 2015 15:58:09 +0100 >> Von: Thomas Schrein (mailinglists) <tsx...@schrein.de> >> An: Robert Helling <hell...@atdotde.de> >> >> >> >> Am 17.03.2015 um 11:48 schrieb Robert Helling: >>> Hi, >>> >>>> On 17.03.2015, at 11:33, Thomas Schrein (mailinglists) >>>> <tsx...@schrein.de <mailto:tsx...@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? >> http://www.automation24.de/prozesssensoren/elektronischer-drucksensor-automation24-pc6706-i10-374-0.htm >> >>> 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”). >> Where can I get it ? >>> For prototyping the logger I would have started with something like >>> 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). >> Looks good for prototyping. I would take a SD device only if I wanted to use >> the SD card for the data transfer to the PC. They burn about 100mA, lot more >> than the processor itself. I wourld prefer SPI FLASH. >> >> As said, we will connect that sensor to our already existing housing (odico) >> and will go diving, the logging function is only a subset of the odico >> functions. So its hard to me to plan for logger an extra prototype/proof of >> concept. >> >> Our next steps would be more focussed in >> 1. integrate the highpressure piezo sensor into a selfmade housing >> 2. build a prototype with an EAGLE designed PCB that fits in a size < 10cm >> >> What about communication? USB / radio ? >> Energy ? Rechargeable or change of the cell ? >> > > I'm kinda in the area of the fewer o-rings the better. Less failure > points. That is a upside with radio/bt.
+1 > I'm also kinda against using rechargeable cells, because of their > failure patterns in a lot of cases. One really nice path that both HW > and Shearwater took with the OSTC3/Petrel is that they just take any > AA-sized cell, and use a internal voltage regulator, so you can run them > of a regular alkaline battery or a SAFT LS14500 if you would like more > battery time. I would rather take rechargeable cells at they allow a smaller form factor. it's much easier to seal everything than have a water resistant housing... > > For the form factor, i would love something that fits on my right post > of my doubles. > > Some nice references about dir-rigged doubles can be found at Peters > site: > http://dir-diver.com/en/equipment/reg_config_doubles.html > > As you see in those pictures, theres quite a bit of room below the right > regulator, or "between" the doubles. Then you can safely store the data > logger nicely tucked away in a protected spot. > > Maybe with a 15cm cable/hp hose between the port and the "brick", > depending on the size of the brick. I wouldn't use a hp hose to connect the sensor with the 1st stage as it increase the risk of failure. I think it's better to connect the sensor to the hp port directly but place the rest of the electronic away from it. so you can have a very tiny sensor and only one hp connection and one O-ring. the 'logger' and battery can be place away at a place where size is nit critical. I also find it very annoying that most or even all wireless pressure sensors are very bulky. it also lead to people carrying the tank holding the wireless sensor :( > The problem comes when you try to use the second hp-port on a stage > bottle. That one is in a really exposed position: > http://dir-diver.com/en/equipment/reg_config_stages.html > > I don't really know how to do something sane there... /martin _______________________________________________ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
