Helvetios board


The Helvetios project (named like this because it’s the star 51 Pegasi, where the first exoplanet was discovered) pretends to be a game board were each hexagon cell it’s retroilluminated and has detection of the pieces over it. This way, the game mechanics could be implemented based in a two way communication with the user: the status of the cells could be showed with the illumination and the user could choose the cell by placing a piece.


The illumination is due with various RGB leds for each cell to have an uniform colour distribution, and the piece detection it’s done with a hall effect sensor, so the piece has to have a very little magnet under it.

Depending if it’s necessary to know the pointing direction of the piece, each cell will have one or three sensors and the piece one or two magnets.

One sensor solution
Three sensors solution

The cells distribution is done in various circuits, the first one has the leds and sensors. The leds are driven by a rgb led controller and the sensors are read by a parallel load shift register:

led circuit

The Helvetios board has 169 cells, to cover them the leds circuits will control 8 cells and the distribution is like this:

Led circuit distribution

To connect them all, a second circuit is needed with only connectors to drive the signals to the led controllers and read the sensors data from the shift registers. Due they are connected in cascade only a few data lines are needed to control them all:

The connection circuits in red

The central cell is the hub where the three ‘arm’ circuits converge. This is the third circuit which has the microcontroller to manage the led drivers and sensors.

Central hub circuit

With these three circuits all the board is covered and could be managed by a higher level software instance to implement the game logics and the players interfaces. This is achieved by connecting the hub circuit via USB to an embedded computer. Also an external power supply is needed for all the electronics.


The required software is divided in three parts:

  • Low level microcontroller firmware: The microcontroller will manage the led drivers to show the desired colour and read the hall sensors. It will adapt all the data to abstract a higher level software to the cell distribution of the board and it’s control. Also will manage an USB connection as a client device and will implement the USB HID protocol.
  • A ‘Gamemaster’ software to manage the data from the USB connection with the board, control the game turns and all the game flow. Also could host an AI player to play against it.
  • A frontend with the interface between the users and the Gamemaster. Could be a web server, to a quick mobile implementation or other data server ad hoc to be used by a client player app.

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