Raspberry Pi Zero Guitar Pedal

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Introduction: Raspberry Pi Zero Guitar Pedal

About: We are MAD about guitar pedals.

Pedal-Pi is a lo-fi programmable guitar pedal that works with the Raspberry Pi ZERO Board. The project is totally Open Source & Open Hardware and made for hackers, programmers and musicians that want to experiment with sounds and learn about digital audio.

You can code your own effects using standard C and get inspiration from the ready-to-use effects from the forum, like the Clean/Transparent, Booster/Volume, Distortion, Fuzz, Delay, Echo,Octaver, Reverb, Tremolo, Looper, etc.

Specifications.

  • Based in Raspberry Pi Zero (1GHz ARM11 core).
  • Analog stages using MCP6002 rail-to-rail operational amplifier.
  • ADC: 12bits / Sampling Rate 50Ksps (MCP3202).
  • Output Stage: 12 bits (2x6bits PWMs running in parallel)
  • Pi Zero:
    • 1GHz ARM11 core.512MB of LPDDR2 SDRAM.
    • Micro-SD card slot.
  • Interface:
    • 2 Configurable push buttons.
    • 1 Configurable toggle switch.
    • 1 programmable blue led
    • .True Bypass Foot-switch.
  • Connectors:
    • Input Jack, 1/4 inch unbalanced, Zin=1MΩ.
    • Output Jack, 1/4 inch unbalanced, Zout=100Ω.
    • Power supply: power taken from the Pi Zero board (micro-USB).

Step 1: Step 1: Get the Components and the PCB.

The electronic components are all through-hole and easy-to-find. You can see the complete list of components here:

For the PCB you can find in the forum a PDF with the transfer files so you can do the PCBs at home, also in the EletroSmash Store there are PCBs for sale:

Step 2: Step 2: Soldering the Circuit.

There is manual that explains how to build the Pedal-Pi step by step with photographs and detailed information:

There is a topic in the forum for any additional question.There is also a Flickr gallery with high-res photos of each step.

Step 3: Step 3: a Closer Look to the Circuit.

There is a detailed analysis of the Pedal-Pi Circuit in the forum:

This hat has three parts:

  • The Input Stage: Amplifies and filters the guitar signal making it ready for the ADC (Analog do Digital Converter). The ADC sends the signal to the PI ZERO using SPI communication. In the forum the topic "Using MCP3202 ADC with Raspberry Pi Zero" gives more details about the ADC-Pi ZERO connection.
  • Pi ZERO: It takes the digitalized audio waveform from the ADC and does all the Digital Signal Processing (DSP) creating effects (distortion, fuzz, delay, echo, tremolo...). In the forum the topic "Basics of Audio DSP in C for Rapsberry Pi Zero" can assist you to learn the basics.
  • The Output Stage: Once the new digital waveform is created, the Pi Zero creates an analogue signal with two PWMs combined, the signal is filtered and prepared to be sent to the next pedal or the guitar amp. For more info check the topic "PWM Audio on Raspberry Pi Zero".

Step 4: Step 4: Start Programming!

Check the "How to Start Programming Pedal-Pi" guide. It is a short guide to start coding this Raspberri Pi Zero guitar pedal. The aim is to understand the basic ideas and then progress as fast as possible through a series of examples.

You are very welcome to upload your ideas and pedals to the forum!

Step 5: Step 5: Create Your Own Sounds.

The best way to progress is to take the basic examples from the forum and try to modify them to fit your taste or set-up. Just changing some values or parameters can make a great difference.

Once you have understood the basic examples, you can think about how to create your own new pedals (reverse delay? reverse-echo?) or mixing some of the examples (fuzz+echo? distortion+delay?). There are tons of unexplored effects to be discovered ;) !

There is a cool review by Blitz City DIY in YouTube: Pedal Pi Kit Review - A Raspberry Pi Zero Guitar Pedal

Audio Contest 2017

Participated in the
Audio Contest 2017

2 People Made This Project!

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30 Discussions

0
SylvainB13
SylvainB13

Question 2 days ago

Hello, great job ! Does it work with the low frequencies of a bass guitar ? Thanks for the answer :-)

0
Antzy Carmasaic
Antzy Carmasaic

1 year ago

Great project! It's amazing what all you have managed to do on Arduino and now on a rpi. I looked through all of your pedals and found that Pedal-Pi is the best option(Due is more complex and less powerful?). Have ordered the parts from Aliexpress(hope they all fit) and looking forward to making the PCB. I do have a few queries which I hope you can answer:
1. Do these have PTH? I do see that you have posted front and back image exports for home-fabrication.
2. Do you have gerbers available? I would like to make them on my CNC mill and can't do that with image files.
3. The board holes for stomp switch are pretty small for the pins for that part. Shouldn't they be elongated slots? It looks like the board in the Blitz City DIY video have correct holes.

0
ElectroSmash
ElectroSmash

Reply 1 year ago

Hi,
1. Do these have PTH? I do see that you have posted front and back image exports for home-fabrication.
Im not sure what is PTH (Plated Through-Hole?). If is that yes, the board has plated pads.
2. Do you have gerbers available? I would like to make them on my CNC mill and can't do that with image files.
Sorry no gerbers available :( We post the front/back copper transfers in the forum:
https://www.electrosmash.com/forum/pedal-pi/237-pedal-pi-native-files-and-pcb-transfers
3.
The board holes for stomp switch are pretty small for the pins for that
part. Shouldn't they be elongated slots? It looks like the board in the
Blitz City DIY video have correct holes. I use the standard parts from KiCAD (which is the open software ECAD that we use for PCB development). The DIP parts have "elongated" pads, but resistos and caps are round. Liz from "Blitz City DIY video" used the standard PCB that we use.

1
Antzy Carmasaic
Antzy Carmasaic

Reply 1 year ago

Thank you for your reply. If they have Plated Through Holes, then it isn't possible to home-fabricate it easily. Since there are no gerbers, I think the only way forward is to recreate the PCB from the copper transfers you have shared. That way I can add vias instead of PTH holes and export as gerber too to make it on my CNC. I'll probably make it on Eagle, so if you are interested, I could send it to you so it could be shared with a larger audience(not everyone uses KiCad :)

0
superlofo
superlofo

Reply 9 months ago

Hello,
I tried to do it without success, too bad :-(
I really want to test this project.
Could you, please, give me the files to create the PCB ?
Thanks

0
craighissett
craighissett

1 year ago

I absolutely love this pedal kit!
I'd love to chain three together under one acrylic top piece. It would be great fun!

0
ElectroSmash
ElectroSmash

Reply 1 year ago

Oh that would be so cool! :o

0
craighissett
craighissett

Reply 1 year ago

Oh yes! I'd probably desolder the jacks apart from the outer input and output, and directly solder them together to keep the signal as clean as possible.
It would be tremendously flexible. I'd love to give it a go one day!

0
KumanT
KumanT

2 years ago

Nice project!

0
ElectroSmash
ElectroSmash

Reply 2 years ago

Thanks!!! ;)

0
ihaveno
ihaveno

2 years ago

would it work on a different Pi?

0
ElectroSmash
ElectroSmash

Reply 2 years ago

It works for sure with the Pi Zero and the Wireless Pi Zero, the code it is developed using the BCM2835 processor libraries.

This processor is also used in the Raspberry Pi Model A, B, B+ and the Compute Module.

Looking at the pinout, the Raspberry Pi 1B+ looks compatible in theory it should work but in practise nobody tried yet.

0
JonathanC96
JonathanC96

2 years ago

Could this work with an Orange Pi One?

0
ElectroSmash
ElectroSmash

Reply 2 years ago

Ive never tried... I am afraid that it wont probably work with the Orange Pi.

0
JackS2SF
JackS2SF

2 years ago

This is stellar! Any recommendations of where in the States to buy all the parts? Think it's attainable for someone with zero programming knowledge like myself or is this too hard of a first project?

0
BlackoutXIII
BlackoutXIII

Reply 2 years ago

The BOM gives part number for Mouser... or, you can order a kit from Electrosmash (linked in the article).

0
JackS2SF
JackS2SF

Reply 2 years ago

Darn, not helpful; so only European suppliers then? Naturally I had checked the Electrosmash page as I read the article and clicked in the links already but would prefer not to order from so far away with 9 business days to ship, ouch. Worth the wait I guess but still a bummer. Thanks anyways.

0
ElectroSmash
ElectroSmash

Reply 2 years ago

We send from UK, but so far all the US shippings go pretty smooth (besides the 9 days shipping time)... If you have any question just drop us an email!

0
Batmantwo
Batmantwo

2 years ago

Any suggestions on where to buy in Australia???

0
ElectroSmash
ElectroSmash

Reply 2 years ago

We provide the Bill of Materials with Mouser references and in the forum you can find the PCB transfers so you can do all DIY at home.

We also have the PCB and complete kits in the store: http://www.electrosmash.com/store/