Tag Archives: Electronics

The Garden Computer Evolving

Just over a year ago I wrote about the Raspberry Pi controller that I built in to a bucket to control the water feature in the kids fairy garden.  The bucket has gone and the controller has evolved in to something much bigger and better IMO.

The controller has gone from using 2x I/O pins for a push button and relay to having an expansion board that runs 4x 240v relays, 8x (with space for another 8) low voltage relays, and 12x Digital I/O pins.  All of these I/O are run from 2x MCP23017 i2c IC’s that give me 16x I/O’s while only using 2x I/O pins from the Raspberry Pi (RPi).  A bonus to this is it also brings a level of isolation which protects the RPi against whatever might happen in the environment.

In addition to this there is now a disused PC power supply that provides a solid +5VDC for the RPi and relay boards, +3.3VDC for some of the garden lights, and at the moment the others stay spare.

The Garden PC Enclosure
The Garden PC Enclosure


In this revision I’ve gone to a complete custom built enclosure.  It’s made from MDF and pine.  While these materials aren’t usually used I have all of the tools to work with wood and not metal.  The back of the enclosure and the door is made from MDF and the other components are made from pine including the top, sides, and divider.

The enclosure is broken in to 2 parts with high voltage (240VAC) on the right and low voltage on the left.  The main reason for this is safety.  I want to keep the separation in case of a catastrophic failure that could put 240V out to the low voltage elements in the garden.

Working through the enclosure, on the right the 240VAC enters the enclosure, goes through the circuit breaker to the connector block and breaks out to the PC PSU and HV relay board.

The PC PSU then supplies the RPi, breakout board, and relay supply boards.

On the right, there’s the PC PSU, Raspberry Pi with WiFi via USB, i2c breakout board, low voltage relay board and connector block for inputs.

The Enclosure, mounting blocks.
The Enclosure, mounting blocks.

This is an overview of the area that the computer is mounted.  The Green blocks on the side of the IBC water tank are the mounting blocks for the enclosure for easy mounting and removal.  The conduit on the wall is for network and power.  The white for network & grey for power.  The flexi-conduit is waiting for the enclosure.

The Enclosure Mounted
The Enclosure Mounted

The enclosure mounted on the blocks with everything closed up.  The blocks on the back of the enclosure have holes in them to drop on to the pins that are on the blocks on the IBC tank.  There’s also a small block on the back of the enclosure at the bottom to make sure it sits out at the same level.

The sloping top is to keep water off the enclosure and out of the seam of the door.  The top is held on with magnets that are usually used for cupboard doors.  This allows for easy removal when I need to open the enclosure.  The door hinges from the left and is held closed with the same magnets as the roof.

The last feature I’ve added is a piece of 70mm PVC Pipe at the bottom with a piece of thin MDF through the middle.  This is just a cable conduit to bring the cables in without exposing the inside to the elements.  The top half is used for low voltage and the bottom is used for high voltage.

There’s not much more really.  On the i2c controller board it has a 1-wire temperature probe which I think I killed in the construction of the board.  I want to eventually add more 1-wire temperature probes to detect inside and outside temperature in case I need to add a fan.  I’ve even thought about putting one in the water feature to keep water running on hot days to keep the algi down.

With any luck I should be able to add the fountain, sprinklers, and some lights to the controller soon.  Then I’ll be working on trying to set up OpenHAB to be able to control this and other items I have networked!


RGB LED Project Idea

I recently purchased a number of WS2812B RGB LED’s from Aliexpress with the intention of doing some fun stuff with them outside.  I failed to notice that they aren’t waterproof and would fail rather quickly.

Inspiration came to me when lying on the couch on the weekend while trying not to zone out too much with the fatigue.  |f I get some thin wire from Jaycar then I could setup a stack of them in the Lego Eiffle tower.  With an Arduino and ethernet shield I could then control it from my phone.  Seems crazy enough so I’ll give it a try.  I’ll post more when it’s done.