Arduino based, Solenoid controlled small garden irrigation

The aim of this application is to keep the garden plants alive, when we are on vacation.

This uses a solenoid valve, controlled by Arduino UNO for feeding the micro irrigation kit.

Equipment inventory

Solenoid valve	1	Electronically controlled water valve
Arduino UNO	1	The main microcontroller
Single channel Relay	1	To control the current through solenoid
Power supplies             5V for Arduino              24 V for solenoid             Optionally 12V for relay	1 1 1
Drip irrigation water feeder tube		Length varies according to the number of plants / pots to be irrigated
Plumbing accessories		To connect the drip irrigation system to main water inlet.

Arduino library

         Time Library (http://www.pjrc.com/teensy/td_libs_Time.html)

         Time Alarms Library(http://www.pjrc.com/teensy/td_libs_TimeAlarms.html)

          DHT11 Library(http://playground.arduino.cc/Main/DHT11Lib)

Connection block diagram

Arduino Code

#include <Time.h> #include <TimeAlarms.h> #include <dht.h> int pin = 10; dht DHT; #define dht_dpin A0; void setup() {   pinMode(pin, OUTPUT);   pinMode(13, OUTPUT);   digitalWrite(pin,LOW);   digitalWrite(13,LOW); // don't want the LED on pin 13 glowing   Serial.begin(9600);   setTime(22,37,00,27,9,2015); // set the date time of your Arduino     Alarm.alarmRepeat(6,0,0, EarlyMorning); // 6:00am every day   Alarm.timerRepeat(3600, Hourly);  // timer for every 2 hours     Serial.println(""); } void loop() {   Alarm.delay(1000); // wait one second between clock display } void EarlyMorning(){   // first thing in the morning open solenoid for 2 mins   Serial.println("Early morning");   solenoid(2); } void solenoid(int min) {   digitalWrite(pin,HIGH); // Open solenoid   delay(min * 60 * 1000);   digitalWrite(pin,LOW); // shut solenoid  } void Hourly() {   Serial.println("Hourly");   // check during daytime only   if( hour() >= 8 && hour() <= 17 && ChkTemp())       solenoid(1); } bool ChkTemp() {   DHT.read11(A0);   // if temp > 30 and humidity > 75%   return (DHT.temperature >= 30 || DHT.humidity >= 75   ); }

Further improvements, to control the solenoid hourly reoccurring function additionally based on moisture level present in the soil rather than just atmospheric temperature and humidity levels.