pih2o 1.0.3
An automatic plant watering application in pure Python for the Raspberry Pi.
License: MIT license
Keywords: Raspberry Pi,Plant,Watering

.. image:: https://raw.githubusercontent.com/anxuae/piH2O/master/templates/pih2o.png
   :align: center
   :alt: PiH2O


The ``pih2o`` project attempts to provide an automatic plant watering application *out-of-the-box*
in pure Python for Raspberry Pi. The watering is triggered for all plants depending on the number
of plants which need water.

Requirements
------------

The requirements listed below are the one used for the development of ``pih2o``, but other
configuration may work fine.

The **pump** can be replaced by an electro valve if the tank water is upper than the plants
(watering by gravity). The number of **soil moisture sensors** can be easily adapted from 1 to 4.
The **transistor** is optional, the sensors can be directly connected to the 5V pin in order
to power them continuously (but it accelerate their corrosion).

Hardware
^^^^^^^^

* 1 Raspberry Pi 2 Model B (or higher)
* 1 pump and its power supply 12V DC (or electro valve)
* 1 to 4 soil moisture sensors (Arduino TE215)
* 1 Analog-to-Digital Converter (ADS1015 or ADS1115 4 Channel I2C)
* 2 transistors NPN (type BC237B)
* 1 transistor PNP high power switch (type BDX34)
* 1 zener diode (type 1N4007)
* 2 resistors of 1.5k Ohm
* 1 resistor of 10k Ohm

Software
^^^^^^^^

* Python ``3.5.3``
* RPi.GPIO ``0.6.3``
* adafruit-ads1x15 ``1.0.2``
* croniter ``0.3.23``
* blinker ``1.4``
* flask ``1.0.2``
* flask-restful ``0.3.6``
* flask-sqlalchemy ``2.3.2``

Install
-------

A brief description on how to set-up a Raspberry Pi to use this software.

1. Download latest Raspbian image and set-up an SD-card. You can follow
   `these instructions <https://www.raspberrypi.org/documentation/installation/installing-images/README.md>`_ .

2. Insert the SD-card into the Raspberry Pi and fire it up. Use the raspi-config tool that is shown
   automatically on the first boot to configure your system (e.g., expand partition, change hostname,
   password, enable SSH, configure to boot into GUI, etc.).

   .. hint:: Don't forget to enable the I2C in raspi-config.

3. Reboot and open a terminal. Install the latest firmware version:

   ::

        $ sudo rpi-update

4. Upgrade all installed software:

   ::

        $ sudo apt-get update
        $ sudo apt-get upgrade

5. Install ``pih2o`` from the `pypi repository <https://pypi.org/project/pih2o/>`_:

   ::

        $ sudo pip3 install pih2o

Run
---

Start the automatic plant watering application using the command::

    $ pih2o

The application acts as a daemon running on the Raspberry Pi. It can be controlled thanks
to an `RESTful API <https://github.com/anxuae/pih2o/blob/master/docs/api.rst>`_.

The ``pih2o`` is scheduled to wake up every given interval, power the soil moisture
sensors and take humidity measurement (or threshold if no analog input available).
Finally the sensors are powered off to extend their lifespan.

.. warning:: Running pih2o in that way use the development server of
    `flask <http://flask.pocoo.org>`_ which is `not suitable in a production
    environment <http://flask.pocoo.org/docs/deploying>`_

Define the record interval
^^^^^^^^^^^^^^^^^^^^^^^^^^

The record interval (i.e. time between each humidity measurement) is defined
in the `Configuration`_ using the `crontab syntax <https://fr.wikipedia.org/wiki/Cron>`_
which is summarized here::

                      ┌───────────── minute (0 - 59)
                      │ ┌───────────── hour (0 - 23)
                      │ │ ┌───────────── day of month (1 - 31)
                      │ │ │ ┌───────────── month (1 - 12)
                      │ │ │ │ ┌───────────── day of week (0 - 6) (Sunday to Saturday)
                      │ │ │ │ │
                      │ │ │ │ │
    record_interval = * * * * *

Pump triggering strategy
^^^^^^^^^^^^^^^^^^^^^^^^

The watering time is defined in the `Configuration`_. The rational to dissociate the pump stop
from the humidity level measured is the soil slow absorption and we want to avoid floor flooding.

Three strategies are defined to detect if watering is required by your plants depending on your
configuration and the number of sensors connected.

* ``[GENERAL][watering_strategy] = majority`` means the pump is triggered if half of sensors
  are triggered.
* ``[GENERAL][watering_strategy] = first`` means the pump is triggered if at least one sensor
  is triggered.
* ``[GENERAL][watering_strategy] = last`` means the pump is triggered if all sensors are
  triggered.

.. note:: if analog channels are available: the sensor is triggered when the humidity read from the AO
          goes below the defined threshold (in %) else if digital channels are available: the sensor
          is triggered if the corresponding DO is set to 1.

Install developing version
--------------------------

If you want to use an unofficial version of the ``pih2o`` application, you need to work from a
clone of this ``git`` repository. Replace the step 5. of the `Install`_ procedure above by the
following actions:

- clone from github ::

   $ git clone https://github.com/anxuae/piH2O.git

- go in the cloned directory ::

   $ cd pih2o

- install ``pih2o`` in editable mode ::

   $ sudo pip3 install -e .

- start the application exactly in the same way as installed from pypi. All modifications performed
  in the cloned repository are taken into account when the application starts.

Configuration
-------------

At the first run, a configuration file is generated in ``~/.config/pih2o/pih2o.cfg``
which permits to configure the behavior of the application. The configuration can be
easily edited using the command::

    $ pih2o --config

The default configuration can be restored with the command (strongly recommended when
upgrading ``pih2o``)::

    $ pih2o --reset

See the `default configuration file <https://github.com/anxuae/pih2o/blob/master/docs/config.rst>`_
for further details.

Circuit diagram
---------------

Soil moisture sensor specification used for this project (the number is up to you but the following
diagram is for up to 4 max):

==================== ==================================
Parameter            Value
==================== ==================================
Input Voltage        3.3 – 5V
Output Voltage       0 – 4.2V
Input Current        35mA
Output Signal        Both Analog (A0) and Digital (D0)
==================== ==================================

Digital sensors
^^^^^^^^^^^^^^^

Here is the diagram for digital sensors (rise to high on dry soil). Depending on the sensor type,
an signal amplifier may be necessary (not represented on this diagram).

.. image:: https://raw.githubusercontent.com/anxuae/pih2o/master/templates/sketch_digital.png
   :align: center
   :alt: Electronic sketch for digital sensors

Analog sensors
^^^^^^^^^^^^^^

Here is the diagram for analog sensors connected to an ADC1115 to measure humidity level.

.. image:: https://raw.githubusercontent.com/anxuae/pih2o/master/templates/sketch_analog.png
  :align: center
  :alt: Electronic sketch for analog sensors

Pump
^^^^

Here is the diagram for the pump (or electro valve). For better understanding the sensors
are not represented here.

.. image:: https://raw.githubusercontent.com/anxuae/pih2o/master/templates/sketch_pump.png
  :align: center
  :alt: Electronic sketch for pump