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D-duino is a platform. Its 0.96 OLED is very useful to display some important information.

Today I successfully displayed temperature and humidity and uploaded to ThingSpeak.

Step 1:

Prepare:

D-duino x1

18650 shield x1

DHT11 sensor x1

Step 2: Connect

Connect DHT11 sensor's RED,BLACK pin to D-duino's 5V and GND.

Connect DHT11 sensor's Green line to D-duino's D4 pin

Step 3: Programming and Test ThingSpeak

Please follow this project :DHTtoThingSpeak

You need to build a new channel with 2 chart.

Remember your API key and copy it to the code.

After changing WiFi ssid and password and API key. You can upload code into D-duino.

Wait several seconds you will find the data displayed on the oled.

Here I set it upload to ThingSpeak every 60 seconds.

Not only DHT sensor but also other sensor is OK!

<p>If you were to have this run on an external battery, how long would it last? Does it have a big draw? Is there a way you could tap into the fridges electricity so it will always have power? </p>
How long depends on how to write the code.<br>Here I set it upload every minutes. So it last only several hours.<br>In fact monitor such things we do not need to monitor it all the time.<br>
<p>Wifi does consume a lot of power, so it won't last long. In this project using a 18650 shield is a good idea, because it means you can recharge the battery every day/week like your smartphone. For long duration, you need to use another radio technology. I personally use panstamps with DHT22 on &quot;battery board&quot; and a single AA alkaline battery (1.5V) goes for 3-4 month. It also monitors the battery voltage, from 1.55V to 0.9V over the weeks. Using a rechargeable 2200mAh AA 1.2V cell would only last 2-3 weeks.</p>
<p>I think the second picture in the first step shows it running off a battery (an 18650 that is labeled as 4800mAh).</p>
<p>Nice project. I too am interested in power consumption /battery life</p>
<p>I understand that bluetooth is a lot less harsh on batteries. Could you hook it up that way?</p><p>Or an example my Lyric thermostat is wifi based, but the Li-on AAA battery that is in there lasts for over a year. And that runs the wifi connection and the lcd display.</p><p>Id love to put one of these in my fridge and then get warnings if the power fails or something so I can realize it before the food gets ruined. </p>
<p>I just built something like this yesterday using Rbpi zero and a DS18B20 plus a USB WiFi module. I chose to use DS18B20 instead of DHT11 because I do not need humidity and have found the temperature accuraty more reliable. The total cost (without general cables) was ~ $18 consisting of the Rbpi zero, a MicroSD card, a DS18B20 and a WiFi module. The system can, of course be extended with DHT11 modules and several Dallas chips.</p>
<p>I agree DHT11 is not reliable. However, I use DHT22 for 5 years now, and it is uncredibly stable 0.1&deg;C precision and regularity, checked with &quot;conventional&quot; thermoter. Actually better than the 18B20.</p>
<p>easyIoT server or easyIoT cloud could be a cheaper sollution for home project. Actually it would cost only ... components price... </p>
<p>30 or 40 bucks for 1 monitor point/how about multiple sensors</p>
<p>you can make the same device (without screen) uploading to blynk smartphone app and even control AC outlets for under $10 (while still able to add multiple sensors) - download &amp; zoom to the attached picture<br><a href="http://www.blynk.cc" rel="nofollow">www.blynk.cc</a><br><a href="http://r.ebay.com/bnNOb3" rel="nofollow">http://r.ebay.com/bnNOb3</a><br></p>
good tutorial

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