In the first week of March, I’ve been asked to run a community art project in Rotherham indoor market with the art organisation ROAR (Rotherham Open Arts Renaissance).
They want a large frame loom weaving with interactive electronic elements that will be jointly made with members of the public. I have designed similar projects before and I am familiar with capacitive touch sensing using micro-controllers. The challenge with this type of project is setting up the hardware so it can be easily used by the participants as I am often not present for the entire duration of the project.
So this week I have been hacking together a system for this project. I decided to try and get the capacitive sensing running directly from the micro-controller – I’ve used MPR121 sensors in the past as they make the process much simpler and you can run multiple sensors through I2C addressing, meaning you can hook up 48 sensor points instead of being restricted to the number of pins on the micro-controller. However, this increases the cost of the components (a major consideration for this type of small community project) and would be fiddly (i.e. fragile) to set up with the type of controller I want to use. I’m using Adafruit Flora micro-controllers for this project – an Arduino based board that has been designed for e-textiles – I’ve selected this board not because the pins can be stitched but because they are large and flat so can be connected with crocodile clips.
So, a lot of this week was spent building and testing the capacitive sensing and outputs (strips of LEDs and piezo buzzers) and working out the code to get the inputs to respond to the outputs.
This is a process of running through the available start-up guides and tutorials, testing parameters, merging code together, testing, adjusting, testing again (a little bit of past experience also helps!). There are also considerations about how to power the system and how they will be integrated into the piece – in this case each ‘module’ (that is set up and pre-programmed Flora) should be low-powered enough to run from LiPo batteries (also a pretty safe option) and they should be easy enough to stick to the frame with some tape – though this will be worked out during the set up as I’ve not built the frame loom myself.
The other consideration is that the delivery of the project is going to be done without my being there for most of it – so once the system is working I had to think about how to make it robust and simple to use. I have set up the Floras so the resistors are solidly connected to the correct pins and then its just a matter of the participants using crocodile clips to connect the boards to the weaving.
I think I’m going to have to write this project up, together with a similar project I ran last year, and publish it on the Instructables. This will serve as a reminder to myself as well as sharing my experiments.