Wireless Guitar Signal Transmitter
A transmitter and a receiver that transmit wireless the guitar signal.
info
Author: Salomia Andrei-Gabriel
GitHub Project Link: link_to_github
Description
This project implements a wireless guitar transmitter based on two Raspberry Pi Pico 2W boards, enabling basic audio transmission over Wi-Fi from a guitar to an amplifier. Additionally, the system allows for volume control, using two buttons to increase/decrease volume level and a mute button.
Motivation
I am passionate about guitar, and I wanted to see if it is possible to create a basic wireless transmitter using low-cost components. Through this project, I am exploring how can I interact with real-time audio while also making my first steps in the world of embedded systems.
Architecture
-
Transmitter (Pico 1):
- Audio input from electric guitar (6.35 mm jack)
- Signal filtering using capacitors
- Analog-to-Digital Conversion (ADC)
- Check for volume changes requests
- Transmit data via Wi-Fi (UDP)
-
Receiver (Pico 2):
- Receive audio data over Wi-Fi
- Digital-to-Analog Conversion using MCP4725 DAC (I2C)
- Signal filtering using capacitors
- Output to amplifier
-
Volume Control:
- 3 buttons to apply volume control
- 3 LEDs indicating the volume settings
System Diagram
Log
Week 28 Apr - 4 May
- Started the documentation for the project, cloned the repository and created the KiCad schematic for the transmitter and receiver, which I'll probably modify later.
Week 12 - 18 May
- Completed the schematic for the transmitter and receiver, including all the components needed for the project. Built the hardware and tested some basic functionalities, such as the ADC and DAC.
Week 19 - 25 May
- Completed the software part. I initially set out to implement some effects, but after completing the wireless transmission part, I realized it would be impossible to create some good sound effects/modulation. I adapted the original effects to just some volume settings. I also tweaked the filters a bit and modifided the schematic as I had made a mistake in the previous version.
Hardware
| Device | Purpose | Usage |
|---|---|---|
| Raspberry Pi Pico W (2 pcs) | Main microcontrollers | Used for Wi-Fi audio transmission and reception, real-time effect processing |
| MCP4725 DAC Board | Digital-to-Analog Conversion | Converts received digital audio into analog output on the receiver side |
| Breadboard HQ 750p (2 pcs) | Prototyping | Assembles and connects the circuit components temporarily |
| Step-Down Converter MP1584EN (2 pcs) | Voltage regulation | Converts 2x18650 battery voltage down to 3.3V for Pico and peripherals |
| Battery Holders for 4 x R6 (2 pcs) | Power supply | Supplies portable power for the transmitter and receiver |
| Jack 6.35mm Connectors (2 pcs) | Audio interfacing | Used for guitar input and amplifier output |
| Buttons (3 pcs) | User input | Selects between different audio effects (mute, tremolo, clipping) |
| LEDs (3 pcs) | Visual feedback | Indicates the currently selected audio effect |
| Capacitors: | ||
| - 100nF | Signal filtering | Used in low-pass filter |
| - 4.7nF | Signal filtering | Used in high-pass filter |
| Resistors: | ||
| - 3.3K Ohm | Signal filtering | Used in low-pass filter |
| - 680K Ohm | Signal filtering | Used in high-pass filter |
| Jumper wires (set) | Connections | Breadboard wiring between all components |
| Headers 1.27mm (2 pcs) | Pico connection | Allows mounting the Pico onto the breadboard securely |
Schematics
Bill of Materials
| Device | Usage | Price |
|---|---|---|
| Raspberry Pi Pico 2W | Main microcontroller (2 units) | 2 × 39,66 RON = 79,32 RON |
| Breadboard HQ 800 Points | Prototyping (2 units) | 2 × 4,56 RON = 9,12 RON |
| Suport de Baterii 4xR6 | Power supply (2 units) | 2 × 3,99 RON = 7,98 RON |
| Modul DC-DC Step-Down MP1584EN | Voltage regulation (2 units) | 2 × 6,49 RON = 12,98 RON |
| Kit Rezistoare 250 buc Plusivo | Biasing, Filters | 14,99 RON |
| Set Fire Mama-Tata pentru Breadboard | Connections | 7.99 RON |
| Header Pini 2.54mm 40p | Mounting Pico on breadboard | (2 pcs) 2.56 RON |
| Buton 6x6x6 | User input | (2 sets of 3) 0.72 RON |
| [LED-uri 5mm și 3mm roșu/verde/galben] | Visual feedback | (12 pcs) 4.68 RON |
| MCP4725 Breakout DAC Board | Digital-to-Analog conversion | 38,86 RON |
| Jack Audio 6.35mm ACJM-IH | Guitar input and amplifier output | (2 pcs) 15,24 RON |
| Condensator FG28C0G1H472JNT06 (4.7nF, ceramic C0G) | Low-pass filter | (10 pcs) 5,92 RON |
| Condensator K104K10X7RF5UL2 (100nF, ceramic X7R) | High-pass | (3 pcs) 2,89 RON |
Software
| Library | Description | Usage |
|---|---|---|
| embassy | Async framework for embedded Rust | Provides async executor, time, networking, and hardware abstraction |
| embassy-net | Embedded async networking stack | Used for UDP communication and network stack setup |
| static-cell | Safe static memory allocation | Used for statically allocated network stack and queue |
| heapless | Fixed-capacity data structures without heap | Used forSPSC queue |
| embedded-hal-async | Async hardware | Used for async I2C communication with the DAC |
| cyw43 | Wi-Fi driver | Enables Wi-Fi connectivity on the Raspberry Pi Pico 2W |