Open Source // v0.1

Ride Connected. Open Road.

OpenHelmet is the open‑source mesh intercom system built for riders who refuse to accept proprietary lock‑in. Real‑time full‑duplex voice for up to 8 riders, on commodity hardware.

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Latency

Riders

16h

Battery

100%

Open Source

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Open Protocol Open Firmware Mesh Networking Full-Duplex Voice ESP32-S3 nRF52840 Opus Codec TDMA + CSMA Zero Lock-In Off-The-Shelf HW Schematics Open Protocol Open Firmware Mesh Networking Full-Duplex Voice ESP32-S3 nRF52840 Opus Codec TDMA + CSMA Zero Lock-In Off-The-Shelf HW Schematics

The Problem

Your helmet,
their rules.

Cardo and Sena dominate motorcycle intercoms with proprietary mesh protocols that lock riders into closed ecosystems. Want to talk to someone on a different brand? Too bad.

Bluetooth Mesh and BLE Audio promise interoperability but deliver high latency, unpredictable scheduling, and poor scaling for continuous audio. They’re fundamentally unsuitable for real‑time group voice.

OpenHelmet takes a different path: a custom real‑time audio transport built from first principles on commodity hardware.

Core Features

Built for the open road.

Mesh Networking

TDMA‑based mesh for 4–8 riders with deterministic latency and zero collisions. Every slot is guaranteed.

Full‑Duplex Voice

Real‑time bidirectional audio with Opus low‑bitrate codec, VOX activation, noise suppression and echo cancellation.

Open Everything

Open protocol, open firmware, open hardware. No reverse engineering—interoperability through standard Bluetooth profiles.

Commodity Hardware

ESP32‑S3 + nRF52840. Off‑the‑shelf dev boards and your existing helmet speakers & mic.

Legacy Interop

Bridge to Cardo, Sena, and others through standard Bluetooth HFP profiles. No proprietary hacks.

All‑Day Battery

Engineered for 8–16 hours of active riding per charge. Go from dawn to dusk without silence.

System Architecture

How it works.

20ms TDMA Frame Structure

Slot 1

Slot 2

Slot 3

...

Slot 8

CTRL

Guard

0ms 16ms voice 2ms ctrl 20ms

Development Roadmap

From prototype
to production.

Phase 1 Complete

Single‑MCU Prototype

ESP32‑S3 with TDMA mesh over ESP‑NOW, Opus voice codec, analog mic/speaker via headphone jack, and VOX activation.

ESP32‑S3

ESP-NOW Opus TDMA VOX 3.5mm Jack

Phase 2 Complete

Dual‑MCU, Production‑Grade

Nordic nRF52 with ESB radio and custom PHY control, SPI audio bridge between MCUs, noise suppression, and echo cancellation.

+ nRF52840

ESB Radio SPI Bridge AEC Noise Suppression

Phase 3 In Progress

Triple‑MCU, Consumer‑Ready

BT5.1 audio SoC for phone integration via HFP profile and audio mixing for legacy intercom bridging.

+ QCC3034

BT5.1 HFP Audio Mixing

Phase 4 Planned

Custom PCB & Enclosure

Custom PCB with integrated audio codec, battery management, enclosure design, and open‑source manufacturing files. Real motorcycle ride testing.

Custom PCB

PCB Design Battery Mgmt Enclosure Ride Testing

Transport Protocol

Engineered for
determinism.

TDMA — Voice

Fixed time slots per node — deterministic latency
Zero collisions — every voice frame is guaranteed delivery
Linear scaling — add riders without exponential overhead
8 × 2ms voice slots = 16ms total voice window per frame

CSMA — Control

Joining and leaving the group dynamically
Topology updates as riders enter and exit range
Slot renegotiation for fair bandwidth allocation
2ms control window per 20ms frame — low overhead

Quick Start

Flash in minutes.

openhelmet ~ bash

# Activate ESP-IDF environment

$ source ~/esp/esp-idf/export.sh

# Build firmware

$ idf.py build

# Flash to your ESP32-S3

$ idf.py -p /dev/ttyACM0 flash

# Monitor serial output

$ idf.py -p /dev/ttyACM0 monitor

I (xxx) omi: ========================================

I (xxx) omi: OpenHelmet - Open Motorcycle Intercom

I (xxx) omi: Opus version: libopus 1.5.2

I (xxx) omi: Free heap: 275432 bytes

I (xxx) omi: ========================================

Mesh Topology

Riders as nodes.

Every rider is a node in the mesh. TDMA ensures each voice stream gets a guaranteed time slot with zero contention.

Bill of Materials

What you need.

ESP32‑S3‑DevKitC

N8R8 variant

XIAO nRF52840

Optional — Phase 2

USB‑C Cables

Data cables, not charge-only

Your Helmet

Existing mic & speakers

Join the
revolution.

OpenHelmet is open source and actively developed. Fork it, flash it, ride with it. Contributions welcome.

View on GitHub

Get Involved

Want to test it
on the road?

We're looking for early testers, hardware tinkerers, and fellow riders who want to help shape OpenHelmet. Whether you want to flash firmware, debug RF issues, or just ride with it — reach out.

I want to help test!

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