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Online temperature Graph

Measuring temperature with a DS18b20, and graphing it online at Open.Sen.Se.

This is the basic principle of the flow of data from the Thermometer to the graph. 
  • The Arduino is needed to talk to the 1-wire sensor (The Imp can't talk 1-wire)
  • 3.3V to 5V - The Imp runs on (and tolerates) only 3.3V on the serial pins. Remember to shift level on the serial line
    • I just run the Arduino off the 3.3V supply from the Imp - The Arduino runs fine on 3.3V

Connecting the DS18b20 to Arduino

There are many many guides to this on the internet. 
Here is the tutorial I used to get it working.

Connecting Arduino to Electric Imp

Biggest issue here is the level conversion. A normal Arduino runs on 5V the Electric Imp runs on 3.3V
Please note: There are a lot of guides to "level shift hacks" out there, and not all are safe to use. 
If you have little electronics knowledge, I recommend you get a "proper" level shifter from someone like Sparkfun.

Using a Logic Level Converter

https://learn.sparkfun.com/tutorials/using-the-logic-level-converter/hookup-examples
Connecting the Electric Imp to Arduino via the Logic Level Converter (From Sparkfun)


Powering the Arduino from the 3.3V from the Imp Breakout board


I solved it by just powering the Arduino from the 3.3V output on the Electric Imp Breakout Board. 
The Arduino works fine on 3.3V, but there is probably a limit to how many mA you can draw from the Imp Breakout Board.
Use at your own risk.

  • Program your Arduino as always
  • Disconnect the Arduino from you computer. And from any other powersource, should it be so
  • Connect Pin5(TX) on the Imp to Pin0(RX) on the Arduino
  • Connect Pin7(RX) on the Imp to Pin1(TX) on the Arduino
  • Connect GND on the Imp to GND on the Arduino
  • Connect 3.3V on the Imp to 5V on the Arduino

Getting your Imp up and running

There are many good tutorials for this at the internet too. Watch out for old ones, though. Electric Imp recently changed the IDE, and if you find any confusing references to "The Planner" - The example you are reading is old and most likely obsolete.

From Electric Imp to Open.Sen.Se

Open.Sen.Se is still in beta and you have to ask for a developer access. 
Open.Sen.Se has gone to greath lengths to make it easy to connect sensors and stuff. The Imp, though, is not specifically mentioned, but the code examples here should help you on. 


Code


Interesting folders:
  • illutronTempAndLightToOpenSenSe 
    • device, agent and arduino code for this guide
  • LightSwitchFromOpenSenSe
    • This example show how to receive data from Open.Sen.Se and use it in the Electric Imp

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