🎸 Guitar Pedal Relay Bypass (PIC12F675)

A silent switching system for guitar effects pedals. This implementation uses a Microchip PIC12F675 microcontroller to control a relay and photoFET, providing a reliable "soft-switch" experience.

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📖 Context

This code is the result of an extensive research series on relay bypass systems. To understand the electronics and the logic behind the code, visit the Coda Effects blog (www.coda-effects.com):

• Relay Bypass: conception and step by step guide - Original logic and step-by-step build guide.
• Relay Bypasswith anti pop system: noiseless and clickless true bypass - Addition of the photoFET for silent operation.
• Relay Bypass: final code - Final version of the code (like the one here!) with explanations.

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✨ Features

• Soft-touch switching: Compatible with momentary (Normally Open) footswitches.
• Non-latching Relay Support: Optimized for standard 5V non-latching relays.
• Debounced input: Software filtering to prevent accidental double-triggering.
• Low power consumption: Minimal current draw, ideal for battery-powered pedals.
• Status LED: Integrated LED control with the bypass state.

🛠 Components

• MCU: PIC12F675
• Relay: 5V Non-latching relay (Takamisawa NA05W-K).
• photoFET: TLP222A.
• Switch: Momentary SPST (Normally Open).
• Voltage: 5V DC (regulated from the pedal's 9V supply).

🚀 Compilation & Flashing

This code is written in C for the XC8 compiler.

1. Open the project in MPLAB X IDE.
2. Ensure the configuration bits are set for Internal Oscillator (INTOSC) to free up GP4/GP5.
3. Disable MCLR in the config bits if you want to use Pin 4 as a general I/O (otherwise, pull it to VDD via a 10k resistor).
4. Flash the hex file using a PICkit 3/4 or any compatible programmer.

⚖️ License

Licensed under the MIT License. You are free to use this in your own builds or commercial products. See LICENSE for details.

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Created by Coda Effects