ElectroSmash, who are a website focused in electronics for audio circuits, contacted us recently to tell us about their pedalSHIELD. It is a programmable Arduino controlled guitar pedal, with all  software tools and programs open source.

Software

It’s aimed at guitarists, as well as hackers and programmers, and is programmed in C/C++.  Users can program their own effects, or download ready effects from the online library.

pedalshield-arduino-guitar-pedal-diagram

Shield

The shield, works in three stages, firstly amplifying the guitar signal and sending it to the microcontroller for sorting. It then does all the Digital Signal Processing, adjusting the signal and incorporating effects like delay, echo, distortion etc…

Finally once the waveform’s processed, the signal’s extracted from the microcontroller’s digital-to-analogue converter and arranged, ready to send to the guitar amplifier.

pedalSHIELDThe shield includes a summing amplifier which is good for any delay effects.

The shield uses 2 ADCs and DACs in unison to meet a higher bit resolution (2 x 12bits). It is possible, however, to use 1 DAC and 1 ADC without the need for changes.

Materials

pedalSHIELD is available to buy online. You can order only the PCB, and use the Bill of materials to build up the kit yourself.

Or, you can order the full kit, which includes everything you need to build the pedalSHIELD. The full kit includes a custom 3D printed cover, by

Schematics

Schematics are available publicly and are created using KiCad. Below is the pedalSHIELD in action.


Things to note: The shield can be programmed in Linux, Windows and Mac. The shield will only work with the Arduino Due. It is suitable for bass players but capacitors C1, C4, C6, C7, C10, C11 need to swap from 0.1uF to 0.5uF. Basic knowledge of C is needed. You can listen to all the already programmed effects at soundcloud.

Specifications:

  • Based in Arduino Due
  • Configurable sampling time from 8kHz to 192kHz
  • More than 2200 instructions per sample at 48kHz
  • Microcontroller: 1. 84MHz 32bit Atmel SAM3X8E ARM Cortex-M3. 2. 96KB RAM, 512KB Flash Memory. 3. Intergrated sampling up to 1Msps.
  • Interface: 1. 3 Configurable potentiometers. 2. 2 Configurable switches. 3. Blue power-on LED PWM controlled. 4. True Bypass Footswitch.
  • Connectors: 1. Input Jack, 1/4 inch unbalanced, Zin=10MΩ. 2. Output Jack, 1/4 inch unbalanced, Zout=1KΩ. 3. Power supply: power taken from Arduino Due board.

Source: ElectroSmash