pigsfoot
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Joined: Sun Feb 14, 2016 11:42 am

Engineer needed to build breakout boards - Old "AirPi" project

Sun Jun 24, 2018 12:27 pm

Hi,

** Upfront disclosure ** This is a business requirement for which we are expecting to pay for a service

I run a business where we provide data to our customers on various applications and data sets ( happy to go into more detail if / when i find someone to work with ). We have a new application where we have been asked if we can start to provide external environmental air quality data.

I know there are various products already on the market but we are looking for something relatively low cost as eventually we will need to deploy several hundred sensors, with this in mind we are looking to build our own sensors based on an RPI or similar platform.

I have looked into an old project called AirPi.. unfortunately it stopped late 2015 but there is still some info around -

http://airpi.es/index.php
https://github.com/guruthree/AirPi

The sensor array on this breakout board looks like the type of thing we are after and the data it provides is perfect for our requirement.

As an initial proof of concept we are looking to build 5 - 10 boards and having spoken to our existing team we have no one with the skills required to build the boards.

Is there anyone on this forum that could help, either building the boards on the basis we just pay for a finished item or point me in the direction of someone that can help.

OR.... maybe there is another active project out there that offers a similar solution to the old AirPi project.

Many Thanks

drgeoff
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Joined: Wed Jan 25, 2012 6:39 pm

Re: Engineer needed to build breakout boards - Old "AirPi" project

Sun Jun 24, 2018 5:04 pm

You need to clarify what you mean by "build". Which ones of the following do you need?

Circuit design.
Procure components.
Assemble
Test

Do the built units merely need to prove the functionality or are you looking for prototypes that are a first approximation to the physical incarnation of later production items? Soldered breadboard or PCB?

And your location in the world can be a significant factor in finding someone suitable.

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mark3112
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Re: Engineer needed to build breakout boards - Old "AirPi" project

Mon Jun 25, 2018 6:53 pm

“we are looking to build our own sensors based on an RPI or similar platform”

I’m with drgoff, that’s way too general.

Are you looking to build a custom sensor module or a PCB housing commercially available components?

The links don’t help when you try and dig down to the details and end up with a page saying Autodesk is closing down.

I can do the Schematic/PCB layout in Altium or OrCAD and use pcbtrain.co.uk for small batches of PCB’s and the likes of TT for mass products and can easily place 0402 components on prototype boards.
You can make a real CPU in a FPGA, but you can’t make a real FPGA in a CPU.

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bensimmo
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Location: East Yorkshire

Re: Engineer needed to build breakout boards - Old "AirPi" project

Mon Jun 25, 2018 9:44 pm

If in the UK then maybe have a chat with Pimoroni. Their EnviropHAT provides half of that with newer sensors.
It doesn't do the gasses though.

As a mock up could just buy the breakout boards and hook them all up.

CharlesII
Posts: 3
Joined: Mon Jun 25, 2018 9:47 pm

Re: Engineer needed to build breakout boards - Old "AirPi" project

Tue Jun 26, 2018 12:28 am

Hello. My name is Charles.
You asked:
Is there anyone on this forum that could help, either building the boards
?
I am a HARDWARE engineer. I build circuit boards (mostly just prototypes).
I do not build sensors - I just purchase them from companies that can mass produce and guarantee some sort of accuracy and reliability.
I do not build the Raspberry Pi - again, just purchase them from others.
If you need to connect different sensors to a rPi, I can build you that board/boards.

Now I have many questions. What shape/size do you need the board [My equipment is limited to about 300x300mm size printed circuit boards, but I prefer to build much smaller ones]? Will it have a certain size constraint or airflow constrictions [fan? fans? This may mean a container - I also do 3D printing for special shapes, but it is much cheaper/easier/faster to do off the shelf boxing]? Does it need its own external power or does it get power from the attached controller [meaning - does the board need a power jack]? What is the power budget? How many sensors per board? You said:
as eventually we will need to deploy several hundred sensors
. Does this mean hundreds of sensors per rPi or just a few sensors each per hundreds of rPies? [I am assuming the latter, so therefor you are eventually looking for hundreds of sensor boards with their individual 'containers' and maybe their own power distributions.] What distances do the sensors need to be from their controlling point(s) [might have problems with noise and need added filtering]? Do the sensors need to be individually removable [for calibration or replacement] or is the entire board removable [which might require higher quality sockets and connectors]? What kind of speeds do you require in the readings, etc.?, etc.
I could go on, but you should get the idea. I live in Atlanta, Georgia USA [for time zone reference].
I build boards. I worry about the hardware.

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Joel_Mckay
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Joined: Mon Nov 12, 2012 10:22 pm

Re: Engineer needed to build breakout boards - Old "AirPi" project

Tue Jun 26, 2018 5:03 pm

Our company also does turn-key manufacturing (we typically won't touch less than 500 unit lots), but your project will likely be more feasible if you contact a local university industry outreach program.

This Pi foundation project already uses the BME280, and I can verify it is quite a reliable little sensor.
https://www.raspberrypi.org/education/weather-station/
https://projects.raspberrypi.org/en/pro ... er-station

In terms of aggregating just a few hundred edge servers, your team will find climbing telephone polls every 5 months far more of an issue. I often use the Pi2/3 SOM for data loggers (since the ARM6 cores), and have numerous stories about their behavior outdoors. Trust that you will need to handle a few things the pi doesn't do very well by itself.

Feel free to ask any questions,
=)

Heater
Posts: 9478
Joined: Tue Jul 17, 2012 3:02 pm

Re: Engineer needed to build breakout boards - Old "AirPi" project

Wed Jun 27, 2018 6:44 am

Joel_Mckay,

Code: Select all

...have numerous stories about their[PI] behavior outdoors.
I'd be interested to hear them.

We have a few PI up polls outdoors that have been running for a year now. Makes me wonder what we have in store.

They are in NEMA enclosures in the baking California sunshine.

A few year back I had one outdoor PI system fail. Turned out not to be a PI problem but the SD card went on fire. Almost literally, the SD got hot and smoked when I got it back on the bench and powered it up.

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Joel_Mckay
Posts: 23
Joined: Mon Nov 12, 2012 10:22 pm

Re: Engineer needed to build breakout boards - Old "AirPi" project

Wed Jun 27, 2018 9:00 am

Hi Heater,
Heater wrote:
Wed Jun 27, 2018 6:44 am
They are in NEMA enclosures in the baking California sunshine.

A few year back I had one outdoor PI system fail. Turned out not to be a PI problem but the SD card went on fire. Almost literally, the SD got hot and smoked when I got it back on the bench and powered it up.
In general, the Pi2/3 should avoid plastic enclosures in industrial settings. Or you too will discover the EMI/EMC profile from the Ethernet chip-set will just barely pass FCC+CE, and fail most other ISO testing. The new pi3 does use a metal can on the SoC, but the other chips should at minimum still use a heat-sink glued on with RTV silicone (don't trust the 3M thermal tape at all temperatures).

Keep in mind our work was mostly for equipment in the Northern oceans, and needed to pass sub -17'C testing in salt-water environments. Almost all plastics (including epoxy) allow some moisture to diffuse into the enclosure over time, and this is is why the equipment we make has large bags of Silica-gel glued into the bottom of the sealed enclosures.
NEMA level certification also doesn't really cover "slow" water-ingress along wiring insulation, and this wire-rot oxidation can even occur during storage. Those expensive weather-proof connectors do offer some protection (albeit a physically brittle one), but a flexible adhesive from Loctite is still recommended in addition to the rubber seals (or at least some Vaseline). Anti-Corrosive Zinc-Paste on the connectors is also a good idea in most cases, as even slightly corroded battery terminals can get very hot.

The sun will bleach and rot most exposed labels/glues/paints within 6 months, so your mounting hardware should take this into account. Most plastics already become very brittle at low temperatures, and not all formulations include UV resistance.

The SDCARD fire could be related to a few issues, but in general... they only fail-closed like that when the supply voltages are exceeded. I would suggest scoping the Pi rail supply under operational loads. Personally, I typically supply regulator power directly into the Pi 5v pins, and use an over sized 2A 3.3v linear LDO regulator for additional sensor chips etc....
Story time, we had a TI chip based power-supply run with bad ceramic capacitors (often an expensive choice normally avoided for filtering switching transients) that would cause ringing well over ripple spec. This ring would take out the rest of the board, and was considered odd as the inductor was purposely over-sized to reduce operating temperatures. Even though the TI chip had respectable over-current protection above the hardware load max... the de-rated high-temperature MLCC could still failed closed after a few months. We even measured a surprising 8A fault through one cap's EIA3216 package. What saved the board, was the fact that we have a design rule where the first part on every module is always a real fuse calibrated for the maximum expected load capacity (we will usually also have a lower valued external in-line fuse for users). Note that ceramic fuses that fail open are usually more reliable than the poly option, but they can also corrode open in high humidity.

Cheers,
~J~

aBUGSworstnightmare
Posts: 768
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Re: Engineer needed to build breakout boards - Old "AirPi" project

Thu Jul 05, 2018 5:57 am

Maybe OP should be more precise WHICH DATA needs to be gathered, so required sensors can be defined.

I.e. for sensing air quality (no of dust particles) one can use i.e. https://eu.mouser.com/ProductDetail/Sha ... H%252bAQ== and for environmental data (pressure, ambient temp, humidity) https://www.bosch-sensortec.com/bst/pro ... cts/bme280 . Add i.e. https://www.intersil.com/en/products/op ... 29023.html for ambient light sensing.

Breakouts for most of the sensors out there are available to start with. Once sensor setup is decided - ad gives OP the data he needs - a technical requirements documents can be made/agreed and someone will be able to make a quote on the costs for such a unit (regardless is small or high quantities).

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Gavinmc42
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Re: Engineer needed to build breakout boards - Old "AirPi" project

Thu Jul 05, 2018 12:30 pm

In some cities, especially in China air particle counts is the most important information.
Honeywell make some that seem to be better than the Sharp one.
https://sensing.honeywell.com/sensors/particle-sensors.

They need lots of indoor and outdoor versions.
Inside, add a CO2 sensor to warn those keeping windows closed.

I have been thinking about a solar powered version with LoRa and wind speed and direction.
Enough of those around and you could warn cities even suburbs in advance.
These guys would be interested? https://publiclab.org/

LoRa is going on Satellites now, so 24/7 World coverage soon for those remote sensors?
I'm dancing on Rainbows.
Raspberries are not Apples or Oranges

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