Archive for January 2013

@crockTweet: Programmable Arduino-Powered PID Sous Vide Slow Cooker

I purchased a very simple slow cooker ($20 at duty free!) a few months ago, which has four settings: High, Low, Keep Warm, and Off.

Most dishes prepared in the slow cooker will cook from 4-8 hours, depending on the setting used. There are a few issues though:
  1. There is no true control of the cooking temperature. 
  2. There is no automated way to switch from one setting to another (e.g. 8-hours of cooking on 'High' followed by 3-hours of 'Keep Warm').
A simple timer attached to the cooker's power plug would allow me to control the total cooking time, but not switch to a new setting, nor would it allow me to precisely control the temperature.

Some more advanced models of slow cookers allow for automated switching of settings, but have no way of notifying me of these things. 

Enter Arduino: an electronics prototyping system that allows the user to interface with the real world through sensors and react to this information based on scenarios coded onto the board through a programming interface.

In the case of the slow cooker, I wanted to use the Arduino to allow me to:
  1. Detect and control the temperature inside the slow cooker based on preset values.
  2. Control the amount of time the slow cooker spends at a selected temperature.
  3. Allow for a multi-step cooking (e.g. 8-hours of cooking on 'High', 4-hours of 'Low', 2-hours of 'Keep Warm').
  4. Tweet the progress (e.g. When the a new process starts or finishes).
I made a quick video of my progress as of last week:

I just finished coding everything, and I theoretically have the ability to do everything I want, except for Tweeting (still waiting for the network interface to arrive in the mail). The nice thing is that this system will work with any slow cooker, as it required no modification of the slow-cooker itself. I will be controlling its on/off state through a solid-state relay controlled by the Arduino, thereby controlling its temperature.

I will be testing everything out tomorrow morning.

Here's my Arduino code:

There is still tuning of the PID parameters to do once I hook everything up, but once that's done, I will post more.

Currently the list of items required for the project (aside from the slow cooker):
  • Arduino UNO Board
  • LCD 20x2 Display
  • DS18B20 Temperature Sensor
  • 20K POT
  • SPST Buttons
  • Breadboard
  • Assorted Resistors
  • Assorted Wires
Stay tuned!

Stuff to read about:
Friday, January 25, 2013
Posted by Konstantine

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I was born in Poland, raised in Ukraine, identify myself as Russian and now reside in Canada. How's that for an identity crisis?

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