AHC - AHC Humidity Control
==============================

This is a demo project I build to monitor and control the humidity in my
daughters room. The software runs on an arduino (uno) board, reads the
humidity from a dht21, and turns on or off a humidifier connected to a relay
module.


  Features
==============================

 - can read humidity from a dht21, dht22 or dht21
 - can read temperature from a ds18b20
 - three operation modes: always off, always on, or automatic
 - web interface to set the target humidity, and change operation mode
 - zabbix agent, to monitor temperature, humidity and output state


  Software requirements
==============================

This project uses the following libraries:

 * EtherCard library
   original: http://github.com/jcw/ethercard
   note: I've altered the ethercard library, to be able to listen on
         multiple prots. Unless it has been merged into the main line,
         please use my version here:
         http://github.com/mrbig/ethercard/tree/f/multi_port

 * DHT library
   http://arduino.cc/playground/Main/DHTLib

 * OneWire library
   http://playground.arduino.cc/Learning/OneWire
   http://www.pjrc.com/teensy/td_libs_OneWire.html

Download the above libraries, and place them under the sketchbook/libraries/
folder. Then make shure you have restarted the arduino ide.

I've build my project using avr-gcc 4.7.2. If you exeperience problems with
older versions of avr-gcc, please try to upgrade first.

  Hardware setup
==============================

This project uses the older Ethernet Shield v1.1. You can obtain it for
several sites for relatively cheap, or the software could be easily modified
to support the new wiznet ethernet shield. Ethernet related code is in the
ethernet.ino file.

The hardware uses currently three io pins:
 - one for the dht
 - one for the one wire communication
 - one is set for output, and is set to high, when the humidifier should be
 turned on.

If any of the input is not working the code will ignore it.

You can set the pins of the above inputs/outpus in the config.h file. This
is where you can set the mac and ip address of the card also.

  Zabbix agent
==============================

There's a self contained zabbix agent implemented in zabbix_agent.ino. The
code makes it easy to add new handlers for the agent: you should place a new
item in the zabbix_config array, where each item is a structure of
ZabbixConfig. These contain the name of the item, and the callback method. 

To respond call the sendZabbixResponse() method. To send an error (when the
monitored item is temporarily not available) call the sendZabbixError
method.

The agent support the 1.4.x passive agent protocol. For unhandled items
automatically the ZBX_NOTSUPPORTED answare is returned.