The requirements

As briefly explained in "About this blog" section, this project is not based on any other project I've found looking around because none of them meets my requirements.

More in deep, the controller has to be able to:

1. set as many watering period I want for each irrigation valve;
2. set different duration for each defined watering period (if needed);
3. water the garden triggered by specific input such as temperature, soil moisture, my cat's mood...
4. postpone the watering according to specific algorithm;
5. log information and send them to a remote site;
6. be managed through a web-based interface (possibly a mobile app too);
7. retrieve the current weather and the short term weather forecast from the web;
8. communicate wireless (I'm not going to manage any other wire along my garden);
9. be powered using the same charger used to drive the irrigation valves (I don't want to buy/change any battery every 6 months).

An Arduino is needed here to address all these nine simple requirements:

1. via software I can manage as many of watering period as I need;
2. via software I can manage as many duration as I want;
3. I can connect to the Arduino all the input I need for the implementation of my specific algorithms;
4. I can develop algorithm as complex as I want directly in C;
5. I'll use a real time clock module and an SD to be sure I can log all the info I want even in case the power is missing (I'm not going to manually set the clock everytime I lost my 220V) and I will use a wifi module to send the log (or any other info);
6. This is not hard but it will take time, I'll use some free online space (maybe in the cloud);
7. connection to the web is a must to solve this point and point number 5 and 6, I just need to use some cloud API for this (Arduino will help);
8. adding a wifi module to the arduino or (better) I'll get an Arduino YUN;
9. I'll use an adapter from 12/24V to 5V (Arduino YUN seams to be choosy).