Tuesday, 28 April 2015

Bud-watch 2015 - part 2

This is a continuation from Bud-watch 2015

The great question on that page, was when the buds would finally open and declare the arrival of spring. The answer this year was just a little bit before the 13th April, when the photos below were taken:

The rhubarb leaves are expanding nicely:

This is one of the first apple buds, photoshopped onto a black background because the greenhouse behind clashed, just toooooo much:

The strawberries are well into their stride.

The apple buds are starting to open. 

The cherry is just beginning to open its buds.

...and the wildlife is on the march too. :-)

There is now a bit of a question about whether a frost will come and knock off all the flower buds, but hopefully now we are just heading right into summer. If there is no frost, it's good for us. If there is a hard frost then it's good for the garden centres, who will be selling oodles of replacement vegetable plants to keen gardeners. One way or another, it's all good. Happy spring to you!

Sunday, 26 April 2015

Raspberry pi temperature sensor

Today we've been having a go at another Raspberry pi project. This one is an O'Reilly "Raspberry Pi Cookbook" recipe.

Just like last time, the process went quite well, but getting the right colours of wires connected to the right terminals was really quite hard. I'm noting it here to help others who may be attempting the same project.

I used this temperature sensor from ebay, with the part number (DS18B20) as listed in the book. The three wires were coloured yellow, red and black, even though the documentation stated that they should be output lead: red (VCC), green (DATA) , yellow (GND).

The wires have to be connected from the pi, to the breadboard, to the temperature sensor as in the diagram in Figure 12-16 in the book.

Below is the bird's eye view of the breadboard. The temperature sensor colours go red, yellow, black from top to bottom. That was the hard part, and once we got it right, we were pretty much there. The pi wires are red at top left, white at bottom left, and black in the middle on the right. The resistor was only 1kΩ, as that was what we had handy and it didn't seem to matter which way it faced.

Below are a few more angles to show the detail:

This photo below also shows the jumpers attached to the raspberry pi, as in the Raspberry Pi Cookbook diagram. The positions are made clear in the book. 

We took the python programme from the website that comes with the book at raspberrypicookbook.com and saved it on the pi as temperature.py.

We controlled from a laptop connected to the pi via putty over the wireless internet. 

It worked just fine except that the very top line of the programme was missing so that it was not automatically run as a python script. We added "#!/usr/bin/env python" to solve this problem. 

We typed "chmod +x temperature.py" just the first time to change the permissions. 

We then used "sudo ./temperature.py" to run the programme each time. This is what the output looked like.

Success! Thank you to Simon Monk, the author. That was fun. 

Friday, 10 April 2015

Good wildlife today

The butterflies are in fantastic form in our garden this week. I have no idea what this one is but it likes our plum tree. We've also had two greenfinches stripping the petals off the tree and flying off with bundles of them poking out from the sides of their beaks. It must be the busy season!

Thursday, 9 April 2015

A new kind of alpine garden

I have been setting up a curve of block paving in the garden with the plan of taking out a few bricks further down the line to plant alpines.

This is a very similar to the planting scheme that Geoff Hamilton used to use in Gardeners' World many years ago when he planted alpines in the gaps between paving slabs in a patio. I'm using block paving because it is cheaper and also easier to make into curves.

I have one plant in a gap so far, and I'm growing a whole lot of mixed alpines from a seed packet from Chiltern Seeds. I'm hoping to fill in lots and lots of little holes with these mixed alpines, so that in the end the bricks are almost entirely obscured.  This is an exercise in cheap-skate, low maintenance gardening!