What is it?

A Samsung HCS-12SS59T 12 character vacuum fluorescent display connected to a custom driver board which takes away all the difficulties of using such a display. The driver board does everything for you, from step-up voltage generation to having a microcontroller that translates between the display and an easy to use I2C interface.

Why did you make it?

I like weird and wonderful displays and this display deserves a spot in cool DIY projects. Unfortunately it is not exactly plug-and-play for use in Arduino, MicroPython or Raspberry pi projects.

What makes it special?

Everything is handled on-board, from generating the required voltages to handling the display control signals. All you have to do is hook up this module via I2C using the QWIIC / Stemma QT connectors on this board. There is two of them allowing for easy daisy chaining with more displays or other QWIIC/Stemma QT boards.


The hardware design files can be found in the hardware repository and the firmware can be found in the firmware repository.

How to use the device

The device can be connected to a microcontroller via the standardized QWIIC interface.


The device is compatible with a supply voltage of 3.3 volt. The I2C interface requires a working voltage of 3.3 volt as well.

I2C interface

The default I2C address is 0x10. The address can be changed by bridging the address jumpers on the board. This allows for modifying the I2C address in the range 0x10 up to 0x2F.

Register map

RegisterNameBit 7Bit 6Bit 5Bit 4Bit 3Bit 2Bit 1Bit 0
0System controlReserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)LED stateTest modeDisplay enable
1Display offsetOffset bit 7Offset bit 6Offset bit 5Offset bit 4Offset bit 3Offset bit 2Offset bit 1Offset bit 0
2Scroll lengthLength bit 7Length bit 6Length bit 5Length bit 4Length bit 3Length bit 2Length bit 1Length bit 0
3Scroll modeReserved (0)Reserved (0)Reserved (0)Loop enableMode bit 3Mode bit 2Mode bit 1Mode bit 0
4Scroll speed HISpeed bit 15Speed bit 14Speed bit 13Speed bit 12Speed bit 11Speed bit 10Speed bit 9Speed bit 8
5Scroll speed LOSpeed bit 7Speed bit 6Speed bit 5Speed bit 4Speed bit 3Speed bit 2Speed bit 1Speed bit 0
6Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)
7Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)
8Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)
9Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)Reserved (0)
10 - 255Data (ASCII)Reserved (0)ASCII bit 6ASCII bit 5ASCII bit 4ASCII bit 3ASCII bit 2ASCII bit 1ASCII bit 0


Front of board
Front of board