# OSIRIS: replacing Onkyo receiver firmware through MCU protocol research

> OSIRIS replaces the DSP-board software of Onkyo TX-NR515 and TX-NR717 receivers with its own boot loader, Linux services and DSP code. The project documents the SPI exchange between the main MCU and DSP board, including 1032-byte transfers, frame structure and command meanings recovered from stock firmware and logs.

- Type: Case study
- Targets: Firmware · Protocol
- Category: Independent reconstruction cases
- Relationship: Independent reconstruction project
- Sources reviewed: 2026-11-06
- Added to the catalog: 2026-11-06
- Original resource: <https://github.com/ubis/OSIRIS>
- Primary source: <https://github.com/ubis/OSIRIS/blob/8515cd884c55f71f1bda35e0efc1586563dfaf6a/docs/mcu-protocol.md>
- Catalog page: <https://awesomerea.org/resources/osiris-onkyo-receiver-case/>
- Record JSON: <https://awesomerea.org/resources/osiris-onkyo-receiver-case/record.json>
- Chinese version: [简体中文](https://awesomerea.org/zh/resources/osiris-onkyo-receiver-case/index.md)

## Requirements & limits

- **Prerequisites:** An Onkyo receiver with a D830 or OMAP-L137 DSP board; installation requires a DSP-board serial connection and BOOT-pin switching.
- **Limits:** The README reports TX-NR717 working and TX-NR515 working with incomplete testing; DTS, Spotify, internet radio and DLNA are unfinished.
- **License:** Original OSIRIS code is BSD-2-Clause; bundled upstream components retain the licenses stated in the README.

## Primary sources

1. <https://github.com/ubis/OSIRIS/blob/8515cd884c55f71f1bda35e0efc1586563dfaf6a/docs/mcu-protocol.md>
2. <https://github.com/ubis/OSIRIS/blob/8515cd884c55f71f1bda35e0efc1586563dfaf6a/README.md>

## More in Firmware and hardware

- [Virtual MPC Sample: rehosting Akai MPC Sample firmware in QEMU](https://awesomerea.org/resources/virtual-mpc-sample-case/index.md) · Case study
- [OpenJooki: replacing the Jooki 2 software and recovery path](https://awesomerea.org/resources/openjooki-jooki2-case/index.md) · Case study
- [Stickwalker: porting Pokéwalker firmware to the Stick S3](https://awesomerea.org/resources/stickwalker-case/index.md) · Case study
- [sony-bravia-linux: pre-Android BRAVIA platform and media behavior](https://awesomerea.org/resources/sony-bravia-linux-case/index.md) · Case study
- [VanMoof BLE: a client for S5, A5 and S6 bicycle protocols](https://awesomerea.org/resources/vanmoof-ble-protocol-case/index.md) · Case study
- [open-picpak: reconstructing the PicPak frame's BLE protocol and device behavior](https://awesomerea.org/resources/open-picpak-case/index.md) · Case study

## 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.