Unit 8Nixie – 8-Digit I²C Display Controlled by MSX0

Have you ever imagined what it would be like if M5Stack released a Nixie tube display in the Unit form factor?

Unit 8Nixie is a prototype that brings that concept to life. It is a compact 8-digit Nixie tube display module that fits perfectly into the M5Stack Unit ecosystem.At its core, it is controlled via I²C commands from the MSX0 Stack — a development board that runs MSX BASIC on M5Stack CORE2.

The motivation behind this project started with the announcement of MSX0 Stack. While exploring M5Stack products, I became fascinated by the design consistency and the ease of use of its Unit modules.

Since the MSX0 is based on a vintage MSX 8-bit computer running at 3.58 MHz, high-speed device control is not ideal. Instead, I realized that I²C-based peripheral control was a great fit — offloading complex tasks to microcontrollers in each Unit.

Meanwhile, I had a long-standing dream to create something with Nixie tubes, especially the compact JRC B-5853S, which fit surprisingly well into a Unit-sized enclosure.After building a 1-tube prototype in 2024, I found it visually underwhelming. So I aimed higher: a full 8-digit display.

Designing the enclosure to fit 8 tubes and sockets in Unit form factor was a challenge, but ultimately rewarding.The key components inside the Unit 8Nixie include:

HV5523 / HV513: high-voltage shift registers for cathode/anode control

• HV5523 / HV513: high-voltage shift registers for cathode/anode control

ATtiny402: microcontroller acting as I²C slave

• ATtiny402: microcontroller acting as I²C slave

External HV unit: a 172V generator enclosed in a UnitProto housing, powered via Grove connector

• External HV unit: a 172V generator enclosed in a UnitProto housing, powered via Grove connector

With a simple MSX BASIC script, you can send display commands over I²C and trigger beautiful digit transitions on the glowing tubes.A retro-inspired concept, built with modern modular components — and compact enough to join your M5Stack lineup.

https://github.com/Ninune-wa/Unit-8Nixie