This blog post is about the design and creative process around the concept of an art object I'm making, to be displayed at the UK Maker Faire in Newcastle in March.
Areas of work
Thermistor for the temperature sensing: test and review the one I have, connect to second life. Temperature should change gradually, not more than 12 degrees in a day I am hoping... so this is rhythm, and will dictate the activities of the avatar that will be connected to it. http://www.maplin.co.uk/Module.aspx?moduleno=2218
A light sensor (or 2?) - test should be working - just got a better resistor and connected a piezo to it. It works. Light readings will be connected to the interrupt, so when it wakes, it will measure all the sensors, write them to eeprom, and then based on the light sensor value and it's change from the previous reading, decides whether to wake up and play.
A battery charge sensor: Very simple to make... the tutorial is online somewhere. Based on this it decides for how long it can play a piece, and wether to play a long sound via the wave shield or just a piezo based generative melody using various smaller, individual wave sounds only towards the end.
thermistor - temperature sensing: Trying with a small bead thermistor, out of 3 bought from maplins. Circuit is almost done.
Plant monitor: Built, working a bit randomly... I plan to show this to Marcus Valentine, get it working properly, measure the resistance on a multimeter (borrow one!), and connect it up to the rest of the device.
Boards and Power Architecture
How much time do I want the musical object to play stuff? Half the day yes half no? And how loud? What to play? Current idea is mornings and evenings. But at night, will it be able to charge from small 3v windmills?!
Find out how much power the whole thing draws and if a second circuit can be built to wake it up.
A solar panel capable of charging enough for power requirements. I looked on solarbotics as well as on Adafruit, but Farnell and other closer ones to the UK (i.e without a 3 week or so delivery time) are probably better.
A way of reducing the power consumption during the night (having only a small battery powered circuit with a timer chip may be a way.
I built a lady ada wave shield with Marcus Valentine's Help.
It has been running "pi", and works fine with this first test program.
Convert a lot of sample music and backgrounds to the correct format from my external hard drive load up samples via SD card reader.
Get a feel for what sounds good alongside the piezos.
Make some ambient recordings also.
Needs to incorporate interrupts and put arduino to sleep until light level changes. Depending on value of light level it chooses weather to play a melody. http://www.uchobby.com/index.php/2007/11/24/arduino-interrupts/
Data logging needs to use EEPROM functions for read/write.
Needs to be able to select and play from wave shield. If easy, play also some shorter files in different speeds, perhaps for shorter concerts.
Cast an initial drone based on average temperature.
(one that slowly moves between averages of readings taken during the night)
duration = readBatterySensor
choose a wave file to play, or a structure using various shorter wav files if there is very little charge.
read from eeprom some sensor values
play values in descending order.
play a melody with beat, melody values, according to how many sensor readings made since last time.
Problem: what if it loses all it's charge while making readings?
IronPython/Open Simulator Code
This script takes serial readings from the arduino and then sends them to a virtual avatar running via LibOpenMetaverse in the 3d world Open Simulator which is an open source world similar to second life. At the moment, it will be easy to trigger a serial call in the form of a command, such as "get readings", or to play one of the sound sources directly.
Some amplification can be done using the shape and texture of clay, wood or plastic. Shape, size and colour will be important aspects.
A suggestion from Tom Bugs is to build it all inside a tube obtained from a hardware shop. Put the solar panel on top, then speaker at bottom and hang it from somewhere. Also there is someone on youtube who has made a balafon from plant pots by securing it in such a way as to allow it to vibrate. Am trying this with wave shield and a small platform with good effect. Plastic, transparent drum skin might be best for light sensor to poke through, and for piezos.
For the Clay part, which I think will be quite important, it is possible to make a DIY kiln, but I've also asked various people and best plan seems to be to go to the art college in clifton and ask to use theirs.