Monthly Archives: September 2014

Screenless programming language: assembling the plug panel

Never seen so many VGA ports, ironic perhaps. It’s great that it’s transparent, but I’m regretting the material choice for the panel – acrylic is horrible to work with and leaves behind lots of microplastics pollution I have to carefully collect up. Lesson learnt for next time, lots more soldering to do now – then more testing with the Raspberry Pi. Following on from the previous post, the instruction blocks will plug in to these 9 pin plugs.

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Migrations in django 1.7

For the wild cricket tales project I’m using django again, the all new 1.7 version which has amongst lots of other shiny things has an all new migrations system. This is so you can change the underlying database ‘model’ for your site and it automatically tracks your changes and applies them to the data (via python scripts it generates and you can tweak if needed).

However, if you trash them (my 0001_initial.py was deleted – not sure what by, or why I didn’t have them in version control but that’s another question) it’s helpful to know how to start again from scratch – the official documentation doesn’t have much to say on this topic yet. This is what I cobbled together, and it requires that your current database matches the code state exactly:

Delete all existing migrations:

rm my-app/migrations/*

Remove references to them from the database – presumably you need to be a little more selective here if you are running more than one app:

sqlite3 db.sqlite3 "delete from django_migrations"

Create new starting state:

python manage.py makemigrations --empty my-app

Fake the initial migration – this will leave the migrations system assuming that the current database state match the code but won’t actually apply the changes (i.e. making the tables again):

python manage.py migrate --fake

I’m still a little unclear how migrations in source control work across development/production servers etc, but time will tell…

Symbai field site testing

Some photos from Shakti Lamba who is currently testing Symbai in the Chhattisgarh state in north eastern India.

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The whole system is solar powered, and provides it’s own networking via the Raspberry Pi synchronisation node shown here. The android tablets also recharge from the same power source. The Raspberry Pi networking is a direct descendant of the experiments we carried out in London during the Sonic Bike workshop.

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Here are three of the tablets syncing their data – photographs for people to identify each other (names are used differently to western culture), audio recordings of verbal agreements (a requirement in preliterate societies), and information of who knows who.

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More on this free software project, links to source etc over at foam kernow.

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Wild Cricket Tales

We have a brand new citizen science project starting with the wild crickets research group at Exeter University! These researchers are examining how evolution works with insects in their natural environment, rather than in lab conditions. In order to do this they have hundreds of CCTV cameras set up recording the burrows of field crickets, resulting in many hundreds of hours of footage. This footage needs to be watched in order to determine the various events that make up the life story of the insects. Each individual it turns out has quite distinct characteristics, and we thought it would be fun to open up this process and make it into a citizen science project – partly to get some help and speed up the job, but also the vast quantity of material (hundreds of thousands of hours in total) has it’s own appeal – and it would be great to be able to use it for a creative project like this.

Here is an example of the footage, rather sped up – check out the frog and the sudden switch to daylight mode:

This is the first interface sketch – my plan is to focus on the individual insects and visualise the information coming together by displaying their characteristics, along with which players are their ‘biggest fans’, i.e the people who’ve put the most time into tagging them:

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The video tagging interface itself is the focus of the first prototype I’m working on at the moment. I’ve got a database set up for storing relationships between crickets, their movies and events that people create based on a combination of django and popcorn.js. Below is the first attempt, the buttons add new events as the movie plays that get recorded on the database, and displayed on the timeline bar at the bottom. Currently all players can see all the events globally, so that’s one of the first things to figure out how to handle.

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Building a screenless programming language for the Raspberry Pi #6

Following on from the last in this mini series, the giant 16 byte multiplexer is finished and tested – lots of head scratching due to shorts and wonky solder joints (it’s amazing how sensitive CMOS logic is, interference on accidental free pins causes strange effects) and I’ve replaced the breadboard with a new interface board between the Pi and the multiplexer.

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Now it’s time to think more about the ‘front end’ – here are some prototype programming blocks made from the ‘holes’ from a hole saw (I’m chopping up bits of driftwood). These include a central drill hole, which we can use for an indicator LED.

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This is the minimal circuitry needed for each programming block – it’s just a 4 bit identification code (reconfigurable via jumpers) and the LED, mounted around the 7 pin VGA style plug.

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Here it’s mounted in the block after a bit of hollowing out. To be fully kid-proof I’ll probably eventually set the internals in epoxy glue.

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Testing the plug/socket wiring on the breadboard. The plan is to paint the top surface of the programming block in blackboard paint so different instructions and languages can be tested and built with the same blocks. It also intriguingly makes abstraction possible, which is usually a problem with non-text based approaches, but this needs more thinking about.

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Here it is with another unenclosed block attached to the main board, and via the new interface to the Raspberry Pi. The interface will need a bit more circuitry to drive the LEDs – which will be able to be lit in different ways depending on the needs of the language, perhaps sequential in some cases, more dependant on logic in others. Also, different shaped blocks or different coloured LEDs may have different meanings in a language too.

Hindi translations in Symbai

A couple of screenshots of the hindi version of Symbai – our solar powered Raspberry Pi/Android anthropological research tool. As is usual we’re still having a few issues with the unicode but it’s nearly there. We’ve been working on this software for the last few months, making sure the data (including photos and audio recordings of verbal agreements) synchronise properly across multiple devices.

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Screenless programming language #5

Update after the last post. After many hours soldering 75% of the board is complete! The Pi can now address a whopping 12 bytes of data.

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After thinking about it for a while, and checking with the languages I’m planning to use – I’ve decided to double the number of instruction ‘slots’ by halving the bits to 4. This doesn’t actually change the core hardware at all – I’ll just scan two at a time and split them in software (part of this project has been to see how much easier it is to change software than hardware). Some of the instructions can span two addresses if needed, but this makes more efficient use of the resources. The ports on the left of the board are where the plugs for the programming ‘interface’ will come in – each one will now split to two locations.

Here’s my test GPIO software running on the Pi, constant testing has been the only way to stay sane on this project. Eventually I could replace the Pi with a microcontroller for some applications, but the Pi has been a great way to ease the prototype process.

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Screen-less programming language (#3)

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Since the last update I’ve connected the Raspberry Pi to the board, and after a bit of debugging I have a python script that polls bytes (more accurately 4 bit ‘nibbles’) via the GPIO ports from 16 addresses. I didn’t blow up the Pi, although I did cause hard resets a couple of times with wandering connections. Now comes the mega wiring phase.

Robot nightjar eggshibition at the Poly, Falmouth

As part of this year’s Fascinate festival we took over the bar at Falmouth’s Poly with visualisations of the camouflage pattern evolution process from the egglab game.

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This was a chance to do some detective work on the massive amount of genetic programming data we’ve amassed over the last few months, figure out ways to visualise it and create large prints of the egg pattern generation process. I selected family trees of eggs where mutations caused new features that made them difficult for people to spot, and thus resulted in large numbers of descendants. Then I printed examples of the eggs at different stages to see how they progressed through the generations.

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We also ran the egglab game in the gallery on a touch screen which accidentally coincided with some great coverage in the Guardian and Popular Science, but the game kept running (most of the time) despite this.

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The Poly (or Royal Cornwall Polytechnic Society) was really the perfect place for this exhibition, with its 175 year history of promoting scientists, engineers and artists and encouraging innovation by getting them together in different ways. Today this seems very modern (and would be given one of our grand titles like ‘cross-displinary’) but it’s quite something to see that in a lot of ways the separation between these areas is currently bigger than it ever has been, and all the more urgent because of this. The Poly has some good claims to fame, being the first place Alfred Nobel demonstrated nitro‚Äźglycerine in 1865! Here are some pages from the 1914 report, a feel for what was going on a century ago amongst other radical world changes:

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