Sensors in the Pyra

Would you be interested in an air pollution sensor, given that we can add one without changing much?

  • Yes

    Votes: 10 32.3%
  • No

    Votes: 21 67.7%

  • Total voters
    31

OppositeDay

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First off, hello to everyone in the Pyra community! I found out about the Pyra just about 3 days ago, read the wiki in pretty much its entirety, lurked (and posted) on the irc a lot, and just created my forum account. I plan to use the Pyra as a phone replacement that, unlike most phones, is not locked down in any way, has a hardware killswitch for the baseband modem, is mostly open, and runs full-on GNU/Linux.

While I was going through the homepage for about the hundredth time, I noticed the part about sensors. Quoting: "a pressure-, humidity- and gas -sensor." While the pressure and humidity sensors aren't all that uncommon, I found the gas sensor part very interesting. I've always thought that a mobile device one can expect to carry with themselves most of the time should have an air pollution indicator, especially indoors. You can imagine my disappointment when I went on the Wiki and saw that the relevant sensor here (Bosch BME280) had no such capability. However, I did find out about the Bosch BME680, a sensor that's about the same size (3mm*3mm vs 2.5*2.5 on the 280), doesn't cost much more, and (I think) could replace the 280 without a redesign of the PCB. It has (open) Linux drivers, and measures VOCs (Volatile Organic Compounds) in the air.

Again, despite it being relatively uncommon, I think the ability to detect hazardous air pollution is quite valuable to have on a portable device that you carry with you pretty much all the time, as a smartphone replacement (which is my use case, and I imagine that of many others as well). Is such a switch plausible, without incurring much additional cost? Would it require a PCB redesign (in which case I might as well forget it), or would it fit the current design? Would it work well in the Pyra's current case, or would it require significant/prohibitive changes? And most importantly, does anyone else like this idea, given that it's convenient to make the switch?
 
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OppositeDay

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This thread needs a poll.
Wasn't sure how to phrase the question at first, hope I did it right.
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Well... welcome to the forums!


Yeah, at this stage, changing anything is a big no. It does seem interesting to have one of those chips.

I was hoping that we wouldn't need to change anything but the model number of the pressure+humidity sensor, since they're probably the same chip with an extra sensor spliced in, or at least very similar in design. They're also nearly the same size.
 

FBnil

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Sprimo and atmotube come to mind. I've read a bit, but it seems you can use the chip only as an alcohol-tester/breathalizer and to know if some paintthinner has been used in a room.
What I would want is O3 (ozone), NO2 (nitrogen dioxide) and CO (carbon monoxide) detectors, which the BME680 apparently does not show. It's like the atmotube, which only has a gauge from 0 to 500 or so... to give "air quality" without specifying what.
Hey I'm getting sleepy... anyone kno...
 

Alperoot

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Well, you could always mod one yourself but I'm weak at the hardware side of things, so I don't know if it's possible or not.
 

levi

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Regarding the poll, I don't see the need for the Pyra to have one - you can always plug one in via usb if you want to. But then again, I'd rather personally have a discrete sensor with a data logger that I can wear on my cycling shorts, and download to my Pyra later when I'm back home. Bagsy not hanging my Pyra off my belt via a flimsy clip. I guess I may end up using my Pyra on the bus and the train, when I'm not on my bike, and numbers from there would be interesting, but a discrete data logging unit would suffice for that as well I think.
 

OppositeDay

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Sprimo and atmotube come to mind. I've read a bit, but it seems you can use the chip only as an alcohol-tester/breathalizer and to know if some paintthinner has been used in a room.
What I would want is O3 (ozone), NO2 (nitrogen dioxide) and CO (carbon monoxide) detectors, which the BME680 apparently does not show. It's like the atmotube, which only has a gauge from 0 to 500 or so... to give "air quality" without specifying what.
Hey I'm getting sleepy... anyone kno...
Do you know of any other such chip that can detect O3/NO2/CO? I'd at least like to mod one in myself, if possible.
 

DaMummy

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It might not be doable at this stage of the project, but I must say, this is how one should ask for features in the future.
 

Bernd

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I think that adding this kind of sensors will add costs to an already expensive device.
Changeing the layout isn't that good too.
Because if the chematics get changed in this stage, the Pyra will be never ready.

Most components are bought too.
 

kabaiakh

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If we're wishing for sensors... Geiger counter.

I'd rather have something like this:
If I do remember the documentaries I watched when kid, it allows you to explore the wider world, live wonderful adventures, make very good friends && eventually get massive superpowers to save the universe.

It would bring a fine addition to an already exceptional device.
Don't you think ?
 

PCXT

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Sensors can be used, but IMHO additional ones as external adapters. This is dictated purely as fault prevention, they like to fail and it'll be easier to replace external adapter than internal parts.
I designed Geiger counter plug-in for HP LX, unfortunately never built as after radiation monitoring in my country shut down I made a stand-alone one. As far as I remember, it's relatively simple thing. Tubes are easily accessible from military surplus (used an old known STS-5 tube). 9V->400V converter can be made drawing ca. 25mA from batteries.
 

rygD

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Would have loved to see that. Maybe you will go back to it one day. It has inspired me to try to find new ways to put my LX back into use.
 

PCXT

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The thing is very, very simple, as I remember:
1. There is a 6F22 battery with ground on LX's serial port GND.
2. There is a transistor-based switch to switch battery on, switching the sensor on. It is driven by LX.
3. Converter based on MC34063, STP6NK60Z MOSFET, UF4007, gives 400V. Warning: Use UF4007 or better. Use X2-grade AC (e.g. 275V) capacitor or it'll blow up.
4. 400V powers tube. This is for STS-5 tube. Tubes DZG/DOG/DOB need lower voltage, but are for different radiation and have awful sensitivity.
5. Tube's other end is driving Zener regulator, then transistors to digital levels, then speaker (to click) and input of LX's port.
6. A whole counting is made by LX.
So you need 2 GPIO pins: one to turn the thing on, second to get pulses. You count pulses in unit of time. This can be done by AVR, RPi or anything having GPIO.
 

FBnil

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Do you know of any other such chip that can detect O3/NO2/CO? I'd at least like to mod one in myself, if possible.
not really, most of the things are small black-box devices, like your 9volt smoke detector.

CO detectors have a limited lifespan, not more than 7 years (as the spot where CO bonds to gets saturated over time). And do not require americium (slightly radio active) like a smoke detector does (well, one kind of them)

All I can say is... read this part (lots of work to make your own):
https://www.quora.com/How-do-I-make...-detector-What-chemical-components-do-we-need
 

netlinker

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I just checked the datasheets of both. If the drawings of the pin spacing and pinout are already correct for the BME680 it just fits and nothing needs to be changed at all.

In case Ed didn't already order the BME 280's, it could be something to take into consideration.

In my oppinion, it's a matter of two factors:
1. Powersupply:
The 680 needs a higher current for heating the VCO sensor
2. Clearances:
One needs to check, if nearby components are a problem, as the sensor is 0.5mm larger in each direction, even tough the pinout remains the same.
 
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