Sous-WeMo

A small script to control a Belkin WeMo switch for sous-vide cooking.

Usage:

Install the required python modules:

sudo pip install -r requirements.txt

Usage:

usage: souswemo.py [-h] [--list] [--mon] [-s 'Switch Name'] [-t TEMP]
               [-T TIME] [-f FUDGE] [-a ACCURACY]

A WeMo switch controller for sous-vide cooking

optional arguments:
    -h, --help        show this help message and exit
    --list            List available WeMo switches
    --mon             Monitor current temperature without controlling a switch
    -s 'Switch Name'  WeMo Switch Name
    -t TEMP           Target Temperature suffixed with either C or F
    -T TIME           Timer in minutes
    -f FUDGE          Fudge factor. Pre-emptively turn switch off/on. Provide value w/ suffix: C or F
    -a ACCURACY       How often to check the temperature in seconds (default 15)

Example:

./souswemo.py -s 'Slow Cooker' -t 60C -T 120

List Switches:

./souswemo.py --list
Starting WeMo listen server
Available switch names are:
['Big lights', 'Little lights', 'Slow Cooker']

Requirements:

• Waterproof DS18B20 One Wire temperature probe. (or other probes supported by the w1thermsensor Python module) Follow these instructions if using a RaspberryPi.
• A GPIO Interface, such as on a RaspberryPi or Beaglebone. VirtGPIO may also work but hasn't been tested.
• Python2.6 and modules listed in requirements.txt

Example:

./souswemo.py -s 'Slow Cooker' -t 75C -T 360
Finding WeMo switches
Turning Slow Cooker Switch on
Device on switch Slow Cooker Switch is at target temperature 75C
Press Enter to start the 360 minute timer
Current temp: 76.062C @ 01:51 PM - Switch Slow Cooker Switch is False

Timer started, start time: 01:51 PM
Current temp: 76.187C @ 01:51 PM - Switch Slow Cooker Switch is False
Current temp: 76.062C @ 01:52 PM - Switch Slow Cooker Switch is False
Current temp: 68.812C @ 01:52 PM - Switch Slow Cooker Switch is False
Turning Slow Cooker Switch on
...
Current temp: 74.875C @ 01:57 PM - Switch Slow Cooker Switch is True
Current temp: 74.937C @ 01:57 PM - Switch Slow Cooker Switch is True
Current temp: 75.0C @ 01:58 PM - Switch Slow Cooker Switch is True
Turning Slow Cooker Switch off
Current temp: 75.0C @ 01:58 PM - Switch Slow Cooker Switch is False
Current temp: 75.0C @ 01:59 PM - Switch Slow Cooker Switch is False
Current temp: 75.062C @ 01:59 PM - Switch Slow Cooker Switch is False
Current temp: 75.062C @ 02:00 PM - Switch Slow Cooker Switch is False
...
Current temp: 74.687C @ 07:50 PM - Switch Slow Cooker Switch is True
Current temp: 74.75C @ 07:51 PM - Switch Slow Cooker Switch is True
Turning Slow Cooker Switch off
Timer 360 mins reached. Switch Slow Cooker Switch is now off
Average temperature was 74.8357018545 with a 30 second accuracy

Troubleshooting:

Q: My switch isn't found but I can see it in the WeMo app.

A: Try increasing the discovery timer

Q: It can't find my temperature probe.

A: Make sure your probe shows up in: /sys/bus/w1/devices/.
If not, check you've added dtoverlay=w1-gpio to your /boot/config.txt (RaspberryPi)

Extra notes:

The WeMo switch gets turned off/on as soon as it hits the target temperature, this can cause a slight fluctuation either side of the target temp.

You can choose to either tweak the accuracy (how often the script checks the temperature), or use -f "Fudge Factor" to pre-emptively trigger the switch slightly earlier.