Home Automation 101

This project started with the challenge to integrate as many Home Automation functions as possible into a Raspberry Pi platform. The requirements were rather simple technically, but challenging due to the sheer number of I/O's required:
- Eight relays for zone heating.
- Eight relays for zone cooling.
- Eight relays for irrigation.
- Eight analog inputs for measuring zone temperatures.
- Eight analog inputs for measuring soil humidity.
- Eight digital inputs for presence detectors.
- Sixteen digital inputs for security sensors.
An off the shelf solution was possible, but required too many components:


The cost was not the main concern, but the implementation. The first prototype used to develop the software resembled a small jungle.
Raspberry Pi in the lower left corner, two USB IO cards from eBay, two 16 relay boards from eBay also. Needed to add ADC channels, but we ran out of space.

So we built the Mega-IO card.

Stack of three Mega-IO cards...
The small tower gives all the relays needed, and more than enough analog and digital channels. It also leaves the Raspberry Pi connector available for another card, if we ever need one.
Technically, the Mega-IO card is not a HAT, because it's form factor is too big - it occupies all the real estate on top of the Pi. In all other aspects is HAT-compliant, so we'll call it an X-HAT (eXpanded HAT).

We developed a command line utility which accesses all the IO functions, available for download HERE.
The easiest way to develop browser software for the Mega-IO card is using the Node Red, a drag and drop visual tool which runs on the Raspberry Pi and can be used for wiring the internet of Things. Click HERE to download a Raspbian operating system image which includes Node-Red and the following examples for accessing Mega-IO functions.
(Alternately, you can download and install Node-Red yourself following the instructions at https://nodered.org/docs/hardware/raspberrypi)

More details in the Kickstarter campaign or on the manufacturer's page.
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