What is it?

The Onion Omega Home Media Center is a compact and neatly designed hardware project that combines the power of the Onion Omega board and the Hi-Fi audio capabilities of the TI’s PCM5100 32-bit DAC. This versatile media center provides a customizable and fully open-source hardware platform for home entertainment.

With a minimalistic but functional design inspired by commercial audio gear, it offers a seamless user experience. It aims to support Airplay, Spotify Connect, LMS, Snapclient and other lightweight protocols that can be integrated into Home Assistant, or any custom use case you may come up with.

Why did I build it

I did few audio projects in the past, some using ESP32, some using larger Orange Pi and Raspberry Pi devices. Each has its pros and cons, and each iteration I'm trying to focus on the details that were working best for me, while actually using them.

Onion is not a powerhouse compared to the Raspberry, but it is much easier to work with, compared to the ESP platform. It has both Ethernet and WiFi onboard (which both Raspberry Pi Zero and Orange Pi One don’t), also it doesn’t rely on the SD card, which makes it indestructible in the long run.

I think Onion Omega is a fun platform to tinker with (although slightly forgotten these days), with a lot of potential yet to be discovered and developed.

Onion Omega HiFi

Onion Omega HiFi is a first-in-line product that uses the legendary PCM5100 series DAC with supreme audio quality. It exposes line-level output that you can plug into a stereo amplifier. Spend as much as you need on the external amp to deliver the sound you like (personally I prefer late 80's audio gear).

Key features

Onion Omega itself

• MIPS MT7688AN CPU running at 580 Mhz
• 64MB (OM-O2) or 128MB (OM-O2P) of RAM
• 16MB (OM-O2) or 32MB (OM-O2P) of Flash storage
• 2.4GHz WiFi
• 10M/100M Ethernet
• USB 2.0 Host
• MicroSD slot (OM-O2P only)

DAC section

• PCM5100A 32bit Stereo DAC
• 2.1 VRMS Line level output
• -100 dB typical noise level

• Triple LP5907 3.3 V Ultra-Low-Noise LDO

• 5V USB-C power adapter

• Mechanical dimensions (WxHxD): 88mm x 38mm x 100mm

Other Peripheral

• Onboard USB-Serial Bridge (UART0)
• Onboard WS2812B LED and LED-Strip header
• IR reader
• TFT SPI Screen header
• External Relay Driver

Board Pinout

Audio

Screen

Other

How to use

Audio

The first thing to do is to follow the official tutorial. The only pitfall is that you need to use a firmware build before b195. I used b193 to be more specific. A full list of old builds can be found here, and instructions on how to flash custom firmware are here.

The issue with later versions is that at some point I2S was disabled in favor of PWM working on the same pins. It can be restored but requires a bit more effort.

As soon as you have proper firmware installed please follow the steps described in the project's repo.

Running pulse-server

There is quite an old write-up that I did in the past. It should be still applicable and fully compatible with HiFi Omega

Screen, IR, RGB led.

This is still a work in progress since it is not one-step instruction. Some links might help to get started

• Ledchain for MT7688
• LIRC on Onion and another one

Hardware

Back	PCB

Please visit hardware section of the project repo for board schematics and PCB designs. Note that PCBs are shared as multi-layer PDFs as well as Gerber archives.