gotmilk

Hackday project for checking milk level in the fridge using a Raspberry Pi and force sensitive resistor.

The Python code posts to a specific room in HipChat - so ensure that you have a .gotmilk file in the directory or in /etc/gotmilk that has this format:

[HipChat]
token=<your HipChat API token>
roomid=<your HipChat room id>

[GotMilk]
delay=2

Writes the last status of the milk to a file \milklevel.txt so that it is possible to ssh into the Pi and see that the Milkmaid is running and monitoring.

Example contents of the file is as follows:

2014-06-05 08:01,650,2.1,Milk running low - please buy more

This is CSV data containing:

Last read date/time
Resistor value - higher values mean LESS pressure (as in less milk)
Voltage - will vary depending on the resistence in the pad (will be higher with less pressure)
Message - this is a text string message (potentially for posting to HipChat)

Messages are sent to HipChat on a specific status change only - i.e. when going from milk being okay to milk being low. Or if there was no milk and then someone bought milk.

Possible messages sent to HipChat:

Milk has all gone (or been left out of the fridge!) - This is shown if the milk has literally all gone or is too low to measure or has been left out of the fridge
Milk running low - please buy more - This is shown if the milk level is getting low
Milk level currently okay - This is shown if there is currently sufficient milk
Milk is plentiful! - This is shown if there is a lot of milk left

Notes on setting up the Pi

ensure raspbian up to date

sudo apt-get update

create main folder

cd /home/pi
mkdir gotmilk
cd gotmilk

install python dev tools

sudo apt-get install python-dev

install spi

mkdir py-spidev
cd py-spidev/
wget https://raw.github.com/doceme/py-spidev/master/setup.py
wget https://raw.github.com/doceme/py-spidev/master/spidev_module.c
sudo python setup.py install

install pip

sudo apt-get install python-pip

use pip to install requests module

sudo pip install requests

copy files over to pi

scp -r * pi@<IP ADDRESS>:/home/pi/gotmilk

setup init.d

sudo cp init.d/gotmilk.sh /etc/init.d
sudo chmod +x /etc/init.d/gotmilk.sh
sudo update-rc.d /etc/init.d/gotmilk.sh defaults

duplicate the config file

cd /home/pi/gotmilk
sudo cp .gotmilk /etc/gotmilk

ensure SPI is available

sudo nano /etc/modprobe.d/raspi-blacklist.conf

Inside this file you will see a line like this:

blacklist spi-bcm2708

You need to ensure it is commented out by putting a # in front of it:

#blacklist spi-bcm2708

Save the file and do a reboot

talis/gotmilk-hack

gotmilk

Notes on setting up the Pi