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Hardware
Ardor is built around a Raspberry Pi 4, a Codec Zero audio board, a touch display, and simple hands-free controls.
Parts for a full pedal
- Raspberry Pi 4B.
- Raspberry Pi Codec Zero audio board.
- Raspberry Pi Touch Display 2.
- The Ardor minimal guitar input buffer board.
- Four momentary footswitches.
- One rotary encoder for master volume.
- A guitar input jack and a stereo audio output jack.
You also need a microSD card and a suitable power supply. Download the ready-made release image before you build the pedal.
Disconnect power before you wire or change the pedal. Raspberry Pi control pins use 3.3 V logic. Do not connect a higher voltage to a control pin. Connect the guitar to the input buffer before you connect it to the Codec Zero.
What each part does
| Part | Purpose |
|---|---|
| Raspberry Pi 4B | Runs the pedal software and the browser manager. |
| Input buffer | Protects and buffers the guitar signal before the Codec Zero. |
| Codec Zero | Converts the buffered guitar signal to digital audio and sends audio to the output. |
| Touch Display 2 | Shows presets, the signal path, controls, and the tuner. |
| Footswitches | Choose the four preset slots in the active bank. |
| Rotary encoder | Sets the master output volume. |
Guitar input buffer
The buffer project is a separate, minimal KiCad board. It sits between the guitar jack and the Codec Zero. Connect the guitar jack toGUITAR_IN. Connect GUITAR_OUT to the Codec Zero input. Share ground, and follow the schematic for power.
You can order the board with its SMD parts already fitted. Upload theGERBER-buffer.zip, BOM-buffer.csv, and CPL-buffer.csv files from the JLCPCB production folder to the JLCPCB assembly service. Review the parts and placement before you order.
The JLCPCB files cover the SMD parts. They do not include jacks, wires, or enclosure parts. Add the signal, power, and ground wires or connectors to the labeled board points after assembly.
Enclosure
The repository contains OpenSCAD files and 3MF meshes for a printable enclosure. The enclosure has space for the display, four footswitches, and the rear encoder.
- Outer size
- 180 × 150 × 55 mm
- Wall thickness
- 3 mm
- Corner radius
- 8 mm
- Display
- RPi Touch Display 2
- Viewable screen
- 125 × 74 mm
- Footswitches
- 4 × 12 mm, corner-inset
- Encoder
- rear-center rotary
- Fixings
- M3 heat-set inserts
Controls
Connect each footswitch and the encoder to the Raspberry Pi control header. The pedal uses the first four footswitches for preset slots. The encoder controls master volume. The display connects through the display cable. The Codec Zero connects through the Raspberry Pi header.
Use the assembly files in the repository for the physical wiring. Test each switch and the encoder before you close the enclosure.
MIDI and expression control
An optional control circuit can add a TRS MIDI input and an expression pedal. These controls can choose preset slots, change banks, open the tuner, or control an effect parameter.
| MIDI message | Action |
|---|---|
| Program Change 0 to 3 | Select preset slot 1 to 4 in the active bank. |
| CC 0 / CC 32 | Select bank 0 to 99. |
| CC 20 ≥ 64 | Open the tuner. A value below 64 closes it. |
Software
The release image contains the pedal software, the browser manager, starter presets, and the audio setup. Follow Getting Started to write the image to a card. You do not need to build the software for a normal setup.
Advanced: control pin map
Use this table when you make a control board. The physical pin numbers refer to the Raspberry Pi header.
| Function | GPIO | Physical pin |
|---|---|---|
| Footswitch 1 / slot 1 | GPIO5 | 29 |
| Footswitch 2 / slot 2 | GPIO6 | 31 |
| Footswitch 3 / slot 3 | GPIO13 | 33 |
| Footswitch 4 / slot 4 | GPIO16 | 36 |
| Encoder A | GPIO17 | 11 |
| Encoder B | GPIO22 | 15 |
| MIDI input (UART4 RX) | GPIO9 | 21 |
| Expression ADC alert | GPIO25 | 22 |
Footswitches and the encoder connect to ground. The Raspberry Pi uses internal pull-up resistors. The pedal reads footswitches through gpio-keys and the encoder through rotary-encoder.
Advanced: audio, display, and control buses
- The Codec Zero uses I2S for audio.
- The Codec Zero uses I2C for control.
- The HAT EEPROM pins are reserved by the Codec Zero.
- The Touch Display 2 uses the DSI display connection.
- MIDI input uses UART4 RX on GPIO9.
- The expression pedal alert uses GPIO25.
Check the assembly files before you change the display or the audio board. A different board can use different pins.