# Wellue O2Ring-S: reconstructing the OxyII BLE protocol

> A protocol study and Python client reconstruct the OxyII Bluetooth LE link used by the Wellue O2Ring-S T8520 pulse oximeter. It documents GATT characteristics, framing, CRC-8 and commands for device information, live SpO2 and heart rate, and stored-file transfer.

- Type: Case study
- Targets: Protocol
- Category: Independent reconstruction cases
- Relationship: Independent reconstruction project
- Sources reviewed: 2026-11-08
- Added to the catalog: 2026-11-08
- Original resource: <https://github.com/nglessner/o2ring-s-protocol>
- Primary source: <https://github.com/nglessner/o2ring-s-protocol/blob/8a1d60367f79f97af68177242657954b0462963a/README.md>
- Catalog page: <https://awesomerea.org/resources/o2ring-s-protocol-case/>
- Record JSON: <https://awesomerea.org/resources/o2ring-s-protocol-case/record.json>
- Chinese version: [简体中文](https://awesomerea.org/zh/resources/o2ring-s-protocol-case/index.md)

## Requirements & limits

- **Prerequisites:** A Wellue O2Ring-S T8520 and a Bluetooth LE connection are required.
- **Limits:** Real-time waveform and PPG sample data have not been decoded or validated; OTA remains unexercised.
- **License:** MIT license.

## Primary sources

1. <https://github.com/nglessner/o2ring-s-protocol/blob/8a1d60367f79f97af68177242657954b0462963a/README.md>

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## About this entry

The description was reviewed against primary sources.
Original editorial content: MIT. Linked projects, papers and assets retain their own rights and licenses.