Now that the system was starting to stabilise, I could look at other power optimisation approaches, since the unit was still taking more than 700ma, most of which goes on the Pi, the wifi adapter and the webcam. 

As luck would have it, I was reading an article about the Raspberry Pi and power reduction techniques for that, one of them was to replace the old, linear regulator on the board with more modern and more efficient switching regulators, this invalidated the warranty, but it reduced the power consumption and by doing so, also reduced the heat output, since the wasted power was released as heat.

With all this hardware, we're going to need some software to bring it all together. Rather than start with WinAVR or Atmel Studio, I decided to use the Arduino framework, since it gives a good boost to a project with its libraries of base functions, so we can start coding our project, not a basic framework for IO. This will also help to keep the children engaged as we get things working more quickly.

Given that this is a chicken house controller, we had better start controlling something. There is also an expectation that the new gadget will do what the off the shelf ones at £70 do and we have spent a lot more than that already. So, we're going to need a lifting mechanism. Luckily, I have a couple of geared motors from "Robby the Robot", who was a previous project that has since been broken down.

Shortly after kicking off development in anger, it became apparent that the SPI programming interface wasn't quite working as I had hoped, it would drop out or fail randomly and in some cases, I had to power cycle the Arduino to get the system talking properly.

After a bit of debugging with the scope, I determined that the SPI programming interface signals were quite noisy, since they come from the Pi, through the interface board, over a jumper cable, onto the main board and across to the Pi. 

It's a fact that if you have chickens, you are going to attract rats, since there is a supply of water and food, but rats come out at dusk when they blend into the background, which makes it hard to deal with them and keep their numbers in check. You can't use poison, since the chickens will eat it too.