Category Archives: Hobbies


The speed of changes of modern tecnology never ceases to amaze me. Got myself a MicroMite – a single chip PIC-32 with MMBasic firmware…..

Result? – add a 47uf tantalum cap, power up at 3.3v an away we go. 100% functional computer with a simple yet powerful Basic interpreter built right in. Amazing. Needs a $5 TTL – USB serial converter but thats it! My TRS-80 had less power than this puppy will get you started including where to source the bits.


Arduino 2!

Well the Arduino project has grown again. I think Arduino must be Italian for spontaneous growth! Here a picture of the latest state.

It now sports a few additions.

– Freetronics Ethershield – It has an integrated prototyping area which holds a “Dead on RTC – DS3234” which is running (as is the Ethershield) on a SPI bus. I had minor moment when, while testing, either the ES or the RTC ran (not both). A bit of digging and the ES needs SPI MODE 0 while the RTC needs MODE 3. The RTC now means that my wife can turn the system off when it rains. Previously you had to turn it back on around the time you started watering but now its agnostic about the startup time.

– Freetronics LCD shield. The buttons on the shield are used to manually start the watering cycle if required.

The stuff which was on the Sparkfun prototype area has all moved to the breadboard including the run LED and the water on LED as well as the driver for the relay. I ran out of digital pins on the Arduino, the LCD uses 7, but the analog pins work fine.

Naturally, if you add ethernet to anything then a web server is required. You can check out the status of my watering system at The other great use of an ethernet interface is you can sync the RTC to NTP on the *net. Its REALLY important that your watering is synced to UTC.

What next? I think a rain sensor is coming as well as the aforementioned connections to the staghorns. Biggest issue there is hiding the ugly black Irrigation pipes!.



Now this is fun. Bought an Arduino / Sparkfun  UNO experimenters kit from Little Bird Electronics. Talk about easy to get running. The little workhorse is now driving the irrigation system in both the upper and lower greenhouses. Here is a pic

I built a 240V -> 24VAC transformer into a jiffy box – its 72VA so I added a 6A fuse. This drives the bodgy little power supply on the left and is switched by the relay into the . 24VAC becomes 12VDC and this then drives the Arduino and the relay. The heatsink on the 7912 voltage regulator is an old Pentium 1 heatsink. Most of the wiring on the breadboard is to

  • accept input from the single switch which either starts or stops the timer
  • drive the piezo which plays a small tune on water on and off
  • drives the servo on the right which provides visual indication of the timer cycle
  • drives the flashing “power (yellow)” and “water on (red)” LEDs
  • holds a single transistor to drive the relay

This is the business end

$19.50 24VAC solenoid from Bunnings and some poly pipe fittings. This irrigation setup is fed by a tank and the valves work OK with this pressure. The fine solenoid cable back to the Arduino is just inserted 100 mm underground using a spade to cut the turf and (this is important) a “stick” to shove the cable to the bottom of the cut. Its not really terminated with insulation tape, there is some soldering and heat shrink under that.

At the moment the Arduino is simply turning it on for 15 minutes every 11 hours and 45 minutes. Future improvements will include

  • A more permanent board for the interfaces
  • LCD for cycle indications
  • A RTC (real time clock) for timing.
  • More relays for different circuits. I need to connect Jacq’s staghorns on the eastern deck into regular watering.

Most of this, of course, is dependant on me not sacrificing the Arduino into the next project……   THIS! Muah-ha-ha