A musical instrument ball is fitted with a micro-controller, accelerometer and a musical instrument shield. Here we're going to program this ball to play drums. But you could use it as any of the instruments present in the musical instrument shield. We're using it as drums because beats are easier to manipulate.
What we'll be needing : -
1) Arduino Uno
2) adxl 345 3-axis accelerometer https://learn.adafruit.com/adxl345-digital-acceler...
3) Sparkfun Musical Instrument Shield https://www.sparkfun.com/products/10587
4) Radio Wave Transmitter and Reciever ( I've used this http://www.aliexpress.com/item/2-4G-Wireless-Link-... You could buy anything that works for you)
5) Acrylic material
6) An american football
7) A switch
8) A 3.7 volt, 5000mah LiPo cell
9) A LiPo charger regulator (something like this https://www.sparkfun.com/products/11231 ) I've used a chinese made product
Step 1: Setting Up the Ball
Remove the strings and cut open the ball. Stitch the two zips at two opposite ends of the ball.
Cut open the bladder at one end and insert an acrylic cylinder. The cylinder is open at one end to insert the arduino
Seal the cylinder and the bladder with super glue.
After the glue dries up . Inflate the bladder and immerse it into water. See if air gaps are present and fix them.
Step 2: Setting Up the Accelerometer, the Midi Shield and Audio Transmitter With Arduino
Break open the audio transmitter box and take off the antenna. I've just used a wire antenna in my project. I've connected both the accelerometer and the audio transmitter to 5 volt arduino pinout.
We're using I2C connections for connecting the arduino to the accelerometer. Connect the sda of the accelerometer to analog pin 4 and scl to analog pin 5.
Put headers on the musical instrument shield and stack it over the arduino. Solder the accelerometer on the shield and stick the audio transmitter on top of it using glue to make the whole setup robust.
Here's the code for the arduino : -
Step 3: Setting Up Everything Inside the Ball
To setup everything inside the ball. I've used two circular disks which just slide into the cylinder perfectly.
Stick the two cylinders to opposite ends of the electronic equipment. Also stick the battery charger to the bottom of the arduino.
Make holes on one of the sides for wires and slide everything into the cylinder.
Make sure the dimensions of the disks are such that they set into the cylinder just right. Electronics inside the cylinder should not wobble when you move the ball around.
Also, make sure it is convenient to take out the battery. Cover the end with wires with soft foam and seal everything up.
You can unzip the ball and charge it anytime you want.