DIY Bluetooth Fridge Monitor | OVERLAND BOUND COMMUNITY

DIY Bluetooth Fridge Monitor

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Aaron Niemi

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Spokane, WA
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Cost about $40 bucks in parts:

1 - Seeeduino (3.3v Arduino Clone) (Seeeduino 4.2 (CFAPN15062) from Crystalfontz )
2 - DS18B20 Temp Sensors (One-Wire Temperature Sensor (WRDOWY17) from Crystalfontz )
1 - BLE BluTooth Module ( )
1 - 12v Buck Converter ( )
1 - 5k resistor to pull-up the temp sensor (it goes between the pwr and data lines, see pic on the following post)

Currently, the App measures the inside temp of the fridge and the outside temp. If the inside temp gets above 40 deg F then it will sound an alarm. If the outside temp gets above 100F it will sound an alarm. If you leave Bluetooth range, it says "goodbye" so you know it's disconnected. I'll probably add other/different features as I think about them.

I used the MIT App Inventor (http://ai2.appinventor.mit.edu/) to build the Android App.
Let me know if you're interested and I'll share my Arduino Sketch and .apk file for the App.

98716
 
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Aaron Niemi

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Member

Member III

2,805
Spokane, WA
First Name
Aaron
Last Name
Niemi
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11381

Here's a photo of the hardware fully assembled.
IMG_20190519_092545.jpg

In the top section is the bluetooth module and a 5k resistor on the "one-wire" temp sensor.
There are two temp sensors daisy chained together (there can be up to 32).

Here's a sensor
IMG_20190521_193625.jpg

in the bottom of the box is a seeeduino (arduino uno clone that has switchable power)
It's power cord is cut off and a buck converter is spliced in to drop the voltage from 12v to 5v so it doesn't smoke the seeeduino.
IMG_20190521_194630.jpg

I attached the Arduino Sketch (StayCool.zip). I hacked it together from a couple sources as you'll see from the code. But it works well so far.
There are some AT commands you have to run on the bluetooth module to get it setup initially, they're in it's datasheet, but if I can figure it out, anybody can.

I uploaded the MIT App Inventor project as well: StayKoolBro_aia.zip You can import it into your own App Inventor account

Holler if you have any questions, I'm happy to help.
-Aaron
 

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britz

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I'll go ahead and order the goods, if I take my time, I can probably do it, but don't be surprised if I start whining. I'm going to try to link this to the Costway thread.
 

Aaron Niemi

Rank V
Member

Member III

2,805
Spokane, WA
First Name
Aaron
Last Name
Niemi
Member #

11381

I'll go ahead and order the goods, if I take my time, I can probably do it, but don't be surprised if I start whining. I'm going to try to link this to the Costway thread.
Awesome! Also get a 5k resistor (forgot to add it to the list) you may already have one laying around. (or I can give you one next time I see you).

I'm sure you can do it, and I can definitely help.
 
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Aaron Niemi

Rank V
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Member III

2,805
Spokane, WA
First Name
Aaron
Last Name
Niemi
Member #

11381

I'm going to add an SDCard to the build so I can log the temps to a file over time.
That'll be in the next feature iteration.
-Aaron
 
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Aaron Niemi

Rank V
Member

Member III

2,805
Spokane, WA
First Name
Aaron
Last Name
Niemi
Member #

11381

Cool stuff Aaron. I have the arb monitor. It doest do outside temp. And cost twice the cash.
Thanks!
Is the ARB one BlueTooth? How far can you get before it disconnects? Does it also have alarms? I'll have to look it up and see what specs it has.
It's way more fun to build it yourself! :)
-Aaron