This weeks blog post is fun version of the DIY Drum kit using the BeagleBone Black, and is something that you can make with friends, at your local maker-space. The STL files for the 3D printed parts are attached to the blog post below at it take about 3 hours to print all the files, I would suggest printing the finger in you favorite color filament first, so that you can add coins and breadboarding wire while the other Beaglebone case parts are printed. Here you will need a friend to help you out to hold the coins and the breadboarding wire while you add hot glue..
The electronic components you will need are
- Beaglebone black
- Adafruits 12-key Capacitive touch breakout - based on MPR121 -https://www.adafruit.com/products/1982
- Beard-boarding wire
- 10K Potentiometer
- USB sound card
- Portable speakers
As you see in the video below the Potentiometer besides the sound card is used to traverse between folders on the Beaglebone which have different sets of sounds like Drums , bass guitar sounds etc..
https://youtu.be/CXhqjeKqedM
If you are looking for another version with more controls check out - Pocket Version of the DIY Drum kit
Here are the steps you will need follow to complete the build
#1 3D print the STL's attached
The parts for 3D printing were designed in 123D design, and you should see 3 STL files in the zip attached below(Fingers.stl,BeagleboneBottom.stl and Beaglebone Top.stl)
Here are some suggested setting to 3D print the parts
- Layer height - 0.2mm
- Infill - rectilinear
- Infill density - 25 %
- Nozzle temperature if you are using the same Filament - 205 C
Note: for the BeagleboneBottom.stl, you will have to add supports as part of your slicer settings
#2 Using Hot glue to add the coins and Breadboarding wire
Here is where you will need a friend to help you out, collect a couple of 10 cents if you like in Canada or based on where you live you will need a coins with a diameter of 18mm.
Add the wires below the coins and using a multimeter run a quick continuity test for all the 5 coins to the tip of the wires.
#3 Soldering components - Capacitive touch breakout and the POT
Now solder some breadboarding wire to the POT
And also solder the ends of the wires from the hand to the MPR121, in my case i have solder another set of wire from the MPR121 to the hand, as I plan on using the breakout board on another version of this project.
#4 Checking if the Capacitive touch Breakout and Sound card are detected by the BeagleBone
Connect the USB sound card to the beaglebone
And connect the MPR121 breakout to the expansion headers on the beaglebone, that is
- Connect the VCC of the key pad to 3.3V , pin#3 on the P9 header
- GND to GND to pin#3 on P9
- SCL on the key pad to pin#19 on P9 header
- and SDA to pin#20
Now connect the Beaglebone to your computer and use the cloud 9 IDE to run the commands below, or use a LAN cable to ssh into the beaglebone to run the following commands
root@beaglebone:~# lsusb
you should see your audio card detected as C-Media Electronics,Inc. CM108 Audio Controller
root@beaglebone:~# i2cdetect -r 1
here you should see the MPR121 detected as 5a , as shown in the screen shot below.
#5 Connecting the Pot to the Beaglebone
Connect the potentiometer to the beaglebone at
- Connect +ve to 1.8V , that is pin #32 VDD_ADC on P9 header
- Connect GND to GNDA_ADC , that is pin #34 on P9 header
- Connect the middle pin of the POT to analog pin #33 on P9 header
#6 Clone the Github repository and run the python program
this is currently a work in progress , and is based on Adafruit's python library for the MPR121, I have currently forked the repo and made some modifications specifically for the beaglebone..(I will have more updates in a couple of days -- stay tuned)
#7 Connect 3D printed Lid to the Top
One you have tested the code add MPR121 breakout the top 3D printed as shown in the picture, the top should snap fit with the base, but add some hot glue if required.
