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Thursday, 29 August 2013

Raspberry Pi: 3x3x3 LED Cube

If you do a web search for LED cubes, you will notice that they have been built so many times and anything less than 8x8x8 is a bit of a waste of time. Knowing all of this, and basically because I am bored out of my mind, I decided to go ahead and build one with old parts lying around at home. 

I ended up with a small 3x3x3 LED cube connected to my Raspberry Pi. I chose 3x3x3 because no extra hardware is needed. All I needed to do was find 27 LED's which I took off an old LED matrix sign board. 

The basic concept is this; the cube, in this case 3x3x3, is made up of columns (9) and layers (3).On each layer, all the cathodes are connected together and in each column, the anodes are connected together. Therefore, 12 ouputs are needed to control all 27 LED's.

By driving the layer output low and the column output high, the specific LED will turn on. Driving both the layer and column output low, will turn the LED off. By sequencing what LED is on when, you can draw different patterns. The bigger the cube, the better patterns can be drawn.

I have drawn up a schematic to show the hardware connections for the cube and the cube to he RasPi's GPIO header.

You can download a schematic here.

Take a look at this 32x32x32 LED cube that someone build.

I wrote my code in Python3.2 using the Rpi.GPIO library.


Wednesday, 28 August 2013

Recipe: Beetroot Burgers

Over the last few weeks I have been on a veggie burger quest. It all started when I tried a SexyFood burger at the Bay Harbour Market in Hout Bay. I enjoy my meat, but am also starting to find the satisfaction in non-meat products. 

These are the burger that I have been buying from SexyFood. They are great but I am not going to be able to get them when I get back home to the UK. So began my quest to create a decent veggie burger. 

I tried some the other day and it all ended in a rather big mess. The base was potato but they just all fell apart. I then kept my eye out for another recipe that had decent comments. That is when I came across The Post Punk Kitchen and this recipe. The comments went on for ages and they were all positive so I decided to give it a go. I made a few small changes but it's pretty much the same. 


  • 2 ½ cups cooked and cooled brown rice
  • 2 cups cooked and drained lentils (1 can)
  • 2 cups grated beetroot (raw) – can also use carrot but haven’t tried that
  • 1 small onion finely chopped
  • Salt and black pepper (add more pepper next time)
  • 1 teaspoon tyme
  • 1 teaspoon dry hot mustard
  • 1 teaspoon chilli powder (add more next time)
  • 1 cup breadcrumbs
  • 2 large tablespoons humus

Mix all ingredients in a bowl. Use food processor to blend. I blended about ¾ of the mixture finely and left ¼ rough to leave some texture, but do it how you prefer. Once blended, it is a relatively dry consistency but packs together well when pressed.

Use a burger press or round mold to form the patties. I cut the top rim off a yogurt container and used that as my mold. My patties were about 10 cm in diameter and around 10-15 mm thick. I wrapped each patty in cling film and put them in the freezer. The ingredients above made 12 patties.

When ready to eat, remove from the freezer and cook from frozen. After about 10-12 min they should be cooked through and ready to eat. Because all the ingredients are grated, they cook really quickly. I am not sure how well they will braai, but with a fine grid I'm sure they will be file. I'll definitely give it a go.

Eat with an avo and you will not be disappointed.

This is what I used for my mold to form my patties.