Controller

Controller/clock for mini Nixie I2C modules

STM32-based controller board that uses 4 nixie modules to display the current time. The modules can be changed at any time the board is off and swapped if the nixie tube goes bad or the user wants to insert a different nixie tube.

The board uses a STM32U031 microcontroller coupled with DS3231 RTC to achieve low power, reliable timekeeping. For High Voltage for the nixie tubes, it uses a premade nixie PSU 160-180V (available on aliexpress). It uses a single cell CR2032 battery to keep the time when the module is not connected. For communication, it uses a serial interface over the USB-C port (which also serves as the power input). The board features 3 programmable buttons and two LEDs for signalling the system status.

Note: V1 version of the board contains multiple test points and additional inputs which will be removed in the V2 version.

Building

Prerequisites:

• Rust
• cargo

To build, simply run cargo build --release

Flashing

The board is flashed using probe-rs, which can utilize a range of multiple programmers, for example an ST-Link. Connect the programmer to the J3 and run cargo run --release.

Operation

Currently, the time can only be set using the serial port and the comm.py script.

The serial protocol for talking to the board can be found in the serial directory

Planned features

V2 will have an option to wire 1 or 2 neon tubes between the hour and minute displays (since not all nixie tubes come with a comma).

It may also be equipped with the human presence sensor to only light up when it can detect a human.

A console interface is planned to utilize all features of the board (such as programming inputs, time, etc.)

The board has a second serial available on pins which may be used for wireless time access via e.g. an esp32.