GTach - Retro styled OBD-II/ELM327 based Tachometer

Created: 2025 08 08

Overview

GTach is an experimental embedded application under development for Raspberry Pi deployment with a Pimoroni HyperPixel Round 480×480 circular touchscreen display. The project implements real-time tachometer functionality via an ELM327 OBD-II adapter.

Notice: This software is experimental and in early development. Fitness for purpose is not guaranteed.

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Table of Contents

• Requirements
• Development Setup
• Build and Deploy
• Running GTach
• Project Structure
• Version History

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1. Requirements

1.1 Deployment

• Raspberry Pi Zero 2W
• Pimoroni HyperPixel Round display (480×480)
• ELM327 OBD-II adapter (Bluetooth SPP)

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2. Development Setup

git clone https://github.com/William12556/GTach GTach

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3. Build and Deploy

3.1 Transfer install script to Pi

scp install.sh root@gtach.local:/opt/gtach/

3.2 Build wheel and transfer to Pi

./build.sh && scp dist/gtach-0.2.22-py3-none-any.whl root@gtach.local:/tmp/

3.3 Install on Pi

/opt/gtach/install.sh /tmp/gtach-0.2.22-py3-none-any.whl

3.4 Retrieve log from Pi

scp root@gtach.local:/opt/gtach/gtach-debug_PI.log ~/Documents/GitHub/GTach/

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4. Running GTach

4.1 Basic usage

gtach [OPTIONS]

4.2 Options

Option	Description	Default
--config PATH	Path to configuration file	Auto-detected
--debug	Enable debug logging	false
--version	Print version and exit	—
--validate-config	Validate configuration and exit	false
--validate-dependencies	Check runtime dependencies and exit	false
--transport MODE	Transport: tcp, serial, rfcomm, simtcp, simbt	None
--obd-host HOST	OBD TCP host	localhost
--obd-port PORT	OBD TCP port	35000
--serial-port PORT	Serial device path	None

4.3 Examples

# Run with debug logging (Pi)
gtach --debug 2>&1 | tee /opt/gtach/gtach-debug_PI.log

# Simulated Bluetooth transport
gtach --transport simbt --debug

# TCP transport to emulator
gtach --transport tcp --obd-host ELM327-Emulator.local --obd-port 35000

# Validate dependencies
gtach --validate-dependencies

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5. Project Structure

ai/           Governance framework
src/          Source code
tests/        Test suite
docs/         Technical documentation
workspace/    Development artefacts (issues, changes, design, requirements)

Return to Table of Contents

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Version History

Version	Date	Notes
1.3	2026-05-20	Updated CLI options in §4
1.2	2026-05-07	Removed macOS runtime support
1.1	2026-05-06	Updated build/deploy workflow
1.0	2025-08-08	Initial README

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Copyright (c) 2026 William Watson. MIT License.