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Postby pasitolonen » Thu Nov 17, 2016 12:00 pm

Hi.

The current setup is as follows. In my car I have a dog crate (for two dogs) and two external fans (12 V) that keep crate cool during the summer time. My intention is to build a system that regulates the temperature so that the external fans will be turned on only when necessary i.e. when measure temperature is above the certain level.

Requirements:

- external temperature sensor(s)
- temperature display, possibly simple 7-segment
- on/off temperature set up buttons +/-
- battery back up and cooling fan for Pi
- relay control board for external fans

I'd like to get your recommendations/ideas for hardware setup for this project.

Thanks!

Pasi

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Postby Jake » Fri Nov 18, 2016 9:17 am

Hi,

Temperature - https://www.modmypi.com/electronics/sen ... re-sensor/
Tutorial demonstates how to measure temperature - you could of course use that value to trigger another script when temp. hits a certain level - https://www.modmypi.com/blog/ds18b20-on ... spberry-pi

Relay board for fans - https://www.modmypi.com/raspberry-pi/br ... lay-board/
Relay board Wiki - https://github.com/modmypi/PiOT-Relay-Board/wiki

Panel mount temperature meter (standalone) - https://www.modmypi.com/electronics/pan ... 70%C2%B0c/

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Postby BMS Doug » Sun Nov 20, 2016 12:38 am

Display + buttons:
Adafruit i2c 16x2 lcd display https://www.modmypi.com/raspberry-pi/breakout-boards/adafruit/adafruit-raspberry-pi-blue-and-white-16x2-lcd-kit/?search=16x2%20lcd

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Postby pasitolonen » Mon Nov 21, 2016 8:54 am

Jake wrote:Hi,

Temperature - https://www.modmypi.com/electronics/sen ... re-sensor/
Tutorial demonstates how to measure temperature - you could of course use that value to trigger another script when temp. hits a certain level - https://www.modmypi.com/blog/ds18b20-on ... spberry-pi

Relay board for fans - https://www.modmypi.com/raspberry-pi/br ... lay-board/
Relay board Wiki - https://github.com/modmypi/PiOT-Relay-Board/wiki

Panel mount temperature meter (standalone) - https://www.modmypi.com/electronics/pan ... 70%C2%B0c/

-- Jake


Panel mount temperature meter is exactly what I was looking for as a temperature display - simple, visible and robust! I've elaborated my original idea so that the system would operate like this.

    1. if temperature is above the level AND car battery level is ok, start fans (relay board)
    2. if temperature is below the level (+ threshold), stop fans
    3. display current temperature (panel mount temperature meter)
    4. configuration and setup through integrated web server

I already have Pi 3/B+, but I guess this project might be suitable for Zero since relay board is designed so that Zero would plug and play. Wifi connection is needed, so I'd need to add this:

https://www.modmypi.com/raspberry-pi/ac ... e-nano-usb

I found this case, but if there are any valid alternatives like a small footprint black/invisible case into which I could integrate the panel, that would great.

https://www.modmypi.com/raspberry-pi/ra ... se-pi-zero

The setup might look better in full black enclosure. Since the system is attached to 12 V cigarette lighter there is also a question how to recognize if car engine is running or not. This is because of the fact that this setup will drain car battery if left running without time-limit while engine is not running. Possible solutions in mind are

    a. motion sensor (if not moving, let's say in 5 minutes, make a wild guess that engine is switched off)
    b. sensor for car battery level (not really interested in messing up with car electronics...)
    c. something else?!?

One possible path might be this:

https://www.modmypi.com/electronics/pan ... -to-30v-dc

Constantly check if voltage is above 11 V and if not, shutdown system.

Pasi

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Postby Jake » Tue Nov 22, 2016 2:09 pm

Hi,

Regarding the case, it's the only one we have that fits a Relay board currently, you could always spray the top black!

You could use a UPS to monitor the voltage?

https://www.modmypi.com/raspberry-pi/br ... /ups-pico/

Obviously if the engines on, then Pi goes on, but if engine is off then Pi would turn off.

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Postby pasitolonen » Wed Nov 23, 2016 2:43 pm

Jake wrote:Hi,

Regarding the case, it's the only one we have that fits a Relay board currently, you could always spray the top black!

You could use a UPS to monitor the voltage?

https://www.modmypi.com/raspberry-pi/br ... /ups-pico/

Obviously if the engines on, then Pi goes on, but if engine is off then Pi would turn off.

-- Jake


Thanks. In fact, if engine is off the system should run as long as there is enough voltage available through 12 V socket. However, UPS is another option, but I think there's no need for secure shutdown rather than just switching the system off. Do you think that both UPS and relay board could fit into that box with Pi3?

Pasi

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Postby Jake » Wed Nov 23, 2016 4:38 pm

Hi

Not sure whether they'll both fit in that box, you might need to get something bigger like a Fibox and just drill holes where you need them.

I would also suggest that you don't just switch the system off without following a proper shutdown procedure. You'll quickly destroy your SD card!

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Postby pasitolonen » Fri Nov 25, 2016 12:56 pm

Jake wrote:Hi

Not sure whether they'll both fit in that box, you might need to get something bigger like a Fibox and just drill holes where you need them.

I would also suggest that you don't just switch the system off without following a proper shutdown procedure. You'll quickly destroy your SD card!

-- Jake


I couldn't find anything like "Fibox" at ModMyPi shop. There seems to be no stackable cases for Pi3 neither?

What are the dimensions of panel mount temperature display and voltage display? I'm just wondering if I were able to mount them into that relay board case and finish the case with black paint. That would be so cool having such an fully integrated solution.

If finding a proper case becomes an issue, I think I'd give it try without UPS since 12 V voltage is always on and I could shutdown system with software when input voltage drops below acceptable level.

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Postby Jake » Mon Nov 28, 2016 10:38 am

Hi

We don't sell the Fibox's as they're not specifically for the Pi, just for "electronics" - they are available from many bigger distribtors e.g. RS/Farnell/Digikey - you'll be able to find one that fits all your gear.

We do a multipi case, but it's not sealed on the sides:

https://www.modmypi.com/search/?search=multipi

To mount to your enclosure, simply cut a 45.5mm × 26.5mm rectangle and snap it in. You'll need about 35mm of space behind for the cables and body. I don't think there's enough space in that relay board case

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