OpenAg-MVP

Code and instructions for building the 'brain' of the controled environment hydroponics unit. It is mostly a collection of python code that runs on a Raspberry Pi (or similar device). See the OpenAg forums for discussion and issues:

The MVP (Minimal Viable Product) is a simplified version of the MIT OpenAg Food Computer.

##Changes

6/21: Added logging of sensor data to CouchDB

Architecture:

The MVP brain is mostly python scripts involed using cron as the scheduler.
Python and cron are built into the Raspbian OS, and the Raspberry library to manipulate GPIO pins is already loaded.

The Python is modular so additions and changes can easily be made without affecting the whole system.

• Scheduling Control (cron)
  • Image capture (webcam.sh)
  • Log Sensors (logSensors.py)
  • Turn lights On (setLightOn.py) _ Tirm lights Off (setLightOff.py)
  • Check Temperature (adjustThermostat.py)

shelf is used for persisting variables (target temperature, prior fan state). These variables must be initialized before the python code will correctly run, this is done by running the Python file /home/pi/python.setup.py. NOTE In my setup, the python icon runs version 3, while clicking a file runs 2.7.9; due to significant differences between versions you have to have consistency with what is run.

Data storage is in a csv formatted (without header) flat file (/home/pi/Documents/OpenAg-MVP/data.txt)

For more information on Cron see:

Hardware Build:

Fan: There are two fans, one for circulation and one for exhausting excess heat These can run off the Raspberry's 5V or from a external 12V transformer

Temperature/Humidity Sensor A si7021 sensor on an I2C bus is used for temperature and humidity. See the following for (instructions)[https://learn.adafruit.com/adafruit-si7021-temperature-plus-humidity-sensor/overview] on use and wiring.

Webcam A standard USB camera is used for imaging (though the Raspberry Pi camera is an option). See here for instructions

Relay A set of relays controled by GPIO pins is used to turn lights on and off (120V), and the exhaust fan (12V)

Pin Assignment:

Refer to the following diagram for the Raspberry's pin names:

Code follows the board number convention.

• '3 - SDA to si7021'
• '5 - SCL to si7021'
• '29 - light relay (relay #4)'
• '31 - (reserved for relay #3)'
• '33 - (reserved for relay #2)'
• '35 - GPIO13 fan control (relay #1)'

Build Activities

Assumptions:

1. NOOB install of Raspbian on Raspberry Pi
2. The Raspbian system has been configured
   • for localization (time, timezone)
   • wifi is established and connected
   • I2C has been enabled
3. 32G SD card to hold data
4. Sensors and relay are wired to the Pi. If you try to run the code without sensors, some of it will error out (I/O Error, I noticed in the getTempC() function). This will ripple up to error out the cron job for logSensorData.py.

Software Build Steps

• Install fswebcam

sudo apt-get install fswebcam

• Download code from Github. Click on the zip file to open it, and move the files to the appropriate location.

  • Right click on the file OpenAg-MVP-master.zip and select 'Extract Here', this will create a directory 'OpenAg-MVP-master that contains the files.
  • Drag the sub-directory 'OpenAg-MVP to the 'Documents' directory
  • Drag the sub-directory 'python' to the 'pi' directory
  • if it does not already exist, create a sub-directory in OpenAg-MVP called "webcam". This will hold the camera images. If it does not exist, the cron job will fail.

• Make webcam.sh executable

  • from the file manager, go to the /home/pi/Documents/OpenAg-MVP directory
  • right click on webcam.sh and select Properties from the menu
  • select the Permissions tab, and on the Execute drop-down select 'Anyone' and hit 'OK'

• initialized shelf with the persistent variables. Double click on the file /home/pi/pythin/setup.py, and Python will open. Click on Run menu, then Run Module sub-menu and run the file. NOTE There needs to be an easier way to set-up cron for new people. The slightest typo will cause it to either not run, or run with errors. Google cron to see how to change the time settings. These will get you going, but you will likely want to change them at some time in the future.

• From a terminal, type:

crontab -e

• Select the second editor option
• Scroll to the bottom of the file and type the following:

*/1 * * * * python /home/pi/python/adjustThermostat.py

This checks the temperature and adjusts the fan every minute

0 6 * * * python /home/pi/python/setLightOn.py

Turns lights on at 6AM (change for your needs)

30 22 * * * python /home/pi/python/setLightOff.py

Turns lights off at 10:30PM (change for your needs)

*/20 * * * * python /home/pi/python/logSensors.py

This logs the temperature and humidity every 20 minutes

1 6-22 * * * /home/pi/Documents/OpenAg-MVP/webcam.sh

This takes an image every hour between 6am and 10pm; avoiding pictures when the lights are out.

CouchDB Install

• Do the usual stuff before making changes

sudo apt-get update

• Don't run an upgrade (sudo apt-get upgrade). Some of the Python code is version 2, and the upgrade will leave you only with version 3; so some of the code will break. Leave things alone so version 2 will be happy.

• build couchdb

sudo apt-get install couchdb -y

The -y will accept all the questions with yes

Modify the default.ini initialization file to allow outside access

sudo leafpad /etc/couchdb/default.ini

_ Under HTTPD,change: binding_address = 0.0.0.0 _ Reboot so this takes effect

Add a database to hold the sensor output

curl -X PUT http://localhost:5984/mvp_sensor_data

In the Python file: logData.py, uncomment the line for logDB

Bill of Materials:

• Raspberry Pi
• 32G SD card
• SI7021 temperature/humidity sensor
• Wire or jumpers
• Relay

Testing:

Individual files can be loaded into Python (double click on the file) and the functions called from the command line. Follow the basic Python code testing processes. testScript.py will go through the main functions and run them. There should be no exceptions, though you will see errors if the si7021 sensor is not correctly wired.

The commands in the crontab file can be run from a command line window:

python /home/pi/python/adjustThermostat.py python /home/pi/python/setLightOn.py python /home/pi/python/setLightOff.py python /home/pi/python/logSensors.py /home/pi/Documents/OpenAg-MVP/webcam.sh

DS18B20 thermometer (optional)

This is a One-Wire sensor. Follow instructions at: https://learn.adafruit.com/adafruits-raspberry-pi-lesson-11-ds18b20-temperature-sensing This is more than Python code, you need to: Add the following to /boot/config.txt

dtoverlay=w1-gpio

Then reboot your Raspberry Then execute the following commands:

sudo modprobe w1-gpio sudo modprobe w1-therm

To Do:

1. Add exception handling to the Python code
2. Add a watchdog to the Raspberry
3. Fix the cron email notifications
4. Automate the build process
   • file movement (clone process?)
   • crontab loading

Future Development (in no priority):

• GUI interface for setting persistent variables (could be local)
• Web interface for charting of data
• Possible move of data to database
• Add a paristolic pump for when have to be away for a while and need to refill the reservoir (Could be a separate board using Particle).
• Light control for controlable LEDs