Playpi Build How to.
Below is how I built on of these, its my custom pattern based sequencer based on the Raspberry Pi and the Adafruit Trellis. The build is actully really simple and its especially handy if you don't have access to a laser cutter!
Below are the parts and tools I needed to build the step sequencer. Most of these tools and parts are quite cheep, and easy to pick up.
- A Drill Press
- A Variable Speed Rotary Tool
- A Raspberry Pi
- Adafruit Trellis Monochrome Driver PCB for 4x4 Keypad & 3mm LEDs x 2
- 32 3mm defuse LEDS (Any color you like!)
- Adafruit Silicone Elastomer 4x4 Button Keypad - for 3mm LEDs x 2
- 4mm A6 Acrylic x 3
- M3 8mm machine screws x 8
- M3 30mm hex spacer x 4
- M3 14mm hex spacer x 4
- M3 8mm grub screw x 4
- M2.5 10m x 4
- M2.5 6mm machine screws x 2
- M2.5 2mm machine screws x 2
- M2.5 4m x 4 hex spacer
- Square Rubber Feet x 4
- Small clamps x 4
- Male to Female hook up wires.
The first thing I did was to take a peace of Acrylic and mark 4 holes on the outside corners. I used of of these below to get the measurements correct on each corner.
Once I did that I took the other two peaces of acrylic, stack them. Remebering to keep the one wih the hole marks on the top. I used clamps to keep them from moving about. I put a 3mm metal drill bit in my drill press.
Note: I had little practice first on a spare sheet before I drilled though 3 sheets at once.
Note: I also though its a good idea at this point to get some safety glasses and gloves on. Acrylic can shatter very easily and the edges can be sharp!
Now for the fun part. I found it best to place an off cut of wood under the drill press. Not only did it save me drilling through me work bench, but I knew I had drilled through the last peace of acrylic as the wood shaving where pulled up though the hole!
I set the height of my drill press so the bit it just above the acrylic. I set mt drill on a low speed, pulling down slowly, but confidently I pulled down on the drill press. I did this four times until I had drilled each hole out. I ensured I had gone right though into the wood below.
Note:I knew from my practising above that pulling to hard would break or shatter your acrylic.
Now that I had that done I knew I could be confident that all the platters will stack neatly and squarely above each other.
Note: At this point I did'nt take the protective plastic off, I had not finished drilling yet!
I took a peace of acrylic, this peace was to be the bottom platter to which I am going to attach the raspberry pi.
Note: Depending on which raspberry pi I am using the (B/B+) the mounting holes are in slightly different places, but the process of getting them there is still the same. Both the modle B and B+ use M2.5 mouting holes as does the Adafruit trellis boards.
I placed the raspberry pi in the middle of my peace of acrylic. Making sure the pi didn't move about I marked the mounting holes on the acrylic.
I took another sheet of acrylic, this one was for the trellis boards.
Again I placed both trellis boards side by side in the middle of the next peace of the acrylic, all I needed to do is mark round the two mounting holes in each trellis boards. I found using the two mounting holes in the middle of the board more then sufficient at keeping the board still. I have not problems with it no matter how hard I hit the buttons.
Change your drill bit to a 2.5mm metal drill bit and drill out each of the holes you have marked.
Now we have one more hole to drill. This is the hole we will use to pass the power and i2c wires from the Pi to the Adafruit Trellis. Take the middle plate (the only the trellis is to be mounted on. Change your drill bit to a 4-6mm drill bit and drill a hole right though the middle of the middle plate.
So now you have 3 peaces of Acrlyic with lots of holes in! Before we get one with soldering we have one last things to do.
Take 4 of your hook up wires. Cut them to about 13cm.
Right its soldering time! Theres no point me rewriting the adafruit instructions on soldering your Trellis so I'm not, because its what I used when I did mine! Head over here for a bit: https://learn.adafruit.com/adafruit-trellis-diy-open-source-led-keypad/adding-leds., then do this https://learn.adafruit.com/adafruit-trellis-diy-open-source-led-keypad/tiling. Then come back to me....
Lets start putting things together!
Remove the protective film from the bottom two platters, take your two M2.5 6mm machine screws and two M2.5 4mm hex spacer and two M2.5 2mm machine screws. Use M2.5 6mm screws to attach the M2.5 4mm hex spaces to the bottom platter and the M2.5 2mm screws to attach the raspberry pi to the M2.5 4mm hex spacers. Take the M3 30mm hex spacers and the M3 8mm machince screws and screw them in around the four cornors of the bottom platter.
Now before attaching the next platter, remove the protective film and thread the four wires you soldered to the trellis thoughtthe center hole in the middle platter. using your four M2.5 6mm machine screws and 10mm hex spacers attache the trellis to the 2nd platter. Now attach the wires to the correct ports on the raspberry pi (5V,GRD,SDA,SCL). Place the 2nd platter on top of the 1st one. Take your 3M 8mm grub screws and put them though 2nd platter into the 3M 30mm hex spacers. Leave 2/3mm of the grub screw out and scerw the 3M 14mm hex spacer onto the top platter. If your in a bit of a hurry to test you can always screw in a 3M machine screw like below....
Next up is the top platter. This is where I really wanted a laser printer. It would make this job so much easier! Nevertheless I dont have one so this is what I did.
I took the top platter, placed it on top of the 2nd platter, and just maked out around the edge of each trellis button pad. I then put a blade on my rotary tool, and cut out 2 square holes. I wont win any awards for it, but I was my last peace of acrylic!
Take your 14mm hex spacers and 4x 3M 8mmscrews. You can screw the 14mm on top of the grub screws on the 2nd platter. Place the top platter on top and just put you 3M screws in.
Thats it, build complete! Simple! You can use the playpi software.Or write you own. I hope you find the guide usefull. Below is a demo of my software in action. Enjoy....