Introduction: DIY 4x4 Arduino Synth Pad
This project takes an Arduino Uno and a variety of other components and turns them into a synth pad which can play a variety of different tones, record those tones and play them back and teach a user how to play new songs.
Step 1: Tools and Components
1. Soldering Iron
3. Wire Strippers
4. Wire/ Resistors
5. Knife / Scissors
6. 3MM LEDs
7. Adafruit Trellis
9. Button, Switch, and Potentiometer
10. 10 segment LED Bar Graph
11. Piezo speaker
12. Enclosure for parts
Step 2: Putting Together/soldering Adafruit Trellis
The Adafruit Trellis is a 4x4 LED button array. It does not come with LED's attached so you must solder them yourself.
1. Get 16 3mm LED's of any color you want (we chose blue).
2. On the Trellis there are 16 spots for the LED's to be connected, each spot having two holes, one for the positive lead and one for the negative lead.
3. One at a time take the LED's and insert the leads into the appropriate holes, making sure the positive lead (slightly longer one), is in the hole marked with a small plus sign.
4. Hold the entire Trellis upside down while applying pressure to the LED so that it seats flat against the face of the Trellis, while holding this position apply a small amount of solder to the spots where the two leads of the LED poke out, securing it in place (we used two sets of hands for this process to make is easier on ourselves).
5. Repeat this process for all 16 LED's making sure they are secure and in the correct orientation while avoiding excess solder and burning other components which are already attached to the Trellis.
6. Once all LED's are firmly secured to the Adafruit Trellis, cut off the excess portion of the leads that stick up above the bead of solder with your wire cutters, making the whole unit nice and neat.
7. Finally, along the middle edge of the Trellis on its underside you will find 5 gold rectangles which you can solder wire to, attach wire to all of these spots (SDA, SCL, GND, 5v), except for the one labeled int, you may want to color code the wires, for instance using a black wire to connect the ground.
Step 3: Wiring the Synth Pad
In this wiring diagram, the Adafruit Trellis is the big square at the bottom and it is where you play the different notes. The LED bar graph, which is the white and red square in the upper left, indicates the pitch of all of the notes and is adjusted by the potentiometer in the upper right of our diagram. Here the red LED just indicates to the user whether or not there is power in the circuit and the piezo speaker, black circle in the center, plays the different notes. The large green button, when pressed plays back whatever series of notes have been played. The toggle switch in the bottom right switches between the free play/ record setting and the learning function where the top 4 LED's on the Trellis flash repeatedly and when selected begin to play a preprogrammed song while lighting up the corresponding buttons for each note, so that the user can learn how to play that song also.
Step 4: Putting the Synth Pad in an Enclosure
For our purposes we used a cardboard box to house all of the hardware. Measure appropriately sized holes for each of the components you need access to (see picture in introduction), making sure there is also a hole in the side to connect the power cord to the Arduino. For the Arduino and the breadboard, we used Velcro to secure them to the inside of the box so that they could easily be removed and reassembled. Keep in mind that you need something to support the Adafruit Trellis when the buttons are being pressed, in this case we used a cut in half water bottle but pretty much any sturdy object can be used.
Step 5: Programming the Synth Pad
There are obviously many different ways to code this synth pad, our code is attached.
We used the Arduino pitches.h file, also attached.
Step 6: Success!
You have completed the project! There is much more that can be done with this synth pad! The possibilities are endless!!!