Arduino Nano Fencing Scoring Box - Foil

A 3D printed box that stands in for a broken scoring machine at club training!

Electronics

1. 1x Arduino Nano ATmega328P
2. 2x 8x8 WS2812B LED matrix panels
3. 6x 1 kOhm resistors
4. 1x 330 Ohm resistor
5. 1x 1000 uF electrolytic capacitor, 10V or higher
6. 1x active 5V buzzer
7. 1x 70 x 50 mm perfboard
8. 5V 2A USB charger

Fencing Parts

1. 2x 3-pin fencing socket blocks (epee-style blocks)

Tools

1. 3D printer
2. Soldering iron
3. Small screwdrivers
4. Wire cutters and wire strippers

Fasteners

1. M3 heat-set inserts
2. M3 and M2 screws

I have attached the STL files used for this build to this Instructable, so you can download them directly here. However, this project may continue to be updated on GitHub, including changes to the STL files, firmware, and documentation. For the latest version, please check the GitHub repository

STL files

1. 1x wedge_body.stl
2. 1x wedge_lid.stl
3. 2x socket_bar.stl
4. 2x diffuser sheets

Print settings:

1. Material: PLA
2. Layer height: 0.2 mm
3. Wall loops: 3
4. Infill: 15% gyroid
5. Diffusers: white PLA, 100% infill

1. wedge_body: sloped face down on the print bed (4 - 5 hrs)
2. wedge_lid: flat on the bed, standoffs facing up
3. socket_bar: flat back on the bed
4. diffuser: flat on the bed

The socket openings are designed around the epee-style socket blocks used in this build. If you want to use separate banana sockets instead, you might want to adjust the hole diameters

Each fencing socket has three lines:

1. Blue = lamé
2. Red = weapon
3. Black = guard

The diagram also reflects the uneven hole spacing of the fencing socket. You can use this spacing to identify which hole is which.

Strip about 10 mm of insulation from each wire and wrap each wire around the socket barrel screw, and tighten the screw firmly.

After wiring, plug in a body cord and test continuity with a multimeter. Check that each socket barrel connects to the expected body cord pin.

The two LED matrix panels are chained together:

1. DOUT from panel 1 to DIN on panel 2
2. V+ from panel 1 to V+ on panel 2
3. V- from panel 1 to V- on panel 2

connect LED Panels to Arduino

1. 5V to V+
2. GND to V-
3. Data input to Arduino D6 through the 330 Ohm resistor

You can arrange the parts on your own perfboard as long as every connection matches the diagram.

- A1 and A4 each need a 1k pull-up to 5V.

- A0, A2, A3, and A5 each need a 1k pull-down to GND.

- The 1000uF capacitor goes across LED 5V and GND, negative leg (striped side) to GND.

- All GND points must be connected together: Nano, both LED boards, buzzer, and all pull-down resistors share one ground.

- Check with a multimeter that 5V and GND are not shorted before plugging in USB!

For each LED window, place the diffuser sheet between the outside cut-out window frame and the LED matrix board. The diffuser is optional, but it makes the LEDs look smoother.

The diffuser has two clearance holes so the printed screw posts are still exposed. Place the LED matrix board inside the case with the LEDs facing outward toward the diffuser, then use M2 screws through the LED board mounting holes. These screws self-tap into the printed plastic posts. Do not overtighten them.

If the diffuser looks too thin, too thick, too bright, too blurry etc.. you can adjust the diffuser thickness and reprint it

For the 3-pin socket blocks, install the socket block from the inside of the body and hold it with the printed socket bar. The socket bar has a correct direction: it must leave clearance for the male body-cord plug to fully insert into the socket block.

The socket bar is fixed with M3 screws into the heat-set inserts in the body

Upload the foil firmware to the Arduino Nano:

foil_box.ino permalink This points to the exact firmware version used for this Instructable.

However this project may continue to be updated on GitHub, for the latest version, please check the GitHub repository

1. Board: Arduino Nano
2. Processor: ATmega328P
3. If upload fails, try: ATmega328P (Old Bootloader)
4. Serial monitor: 57600 baud

After uploading the firmware, all four light zones should turn on, the buzzer should beep once, and then the boot sweep should light up from left to right in this order: white, red, green, white. If the order, rotation, or layout is wrong, adjust the display mapping constants in the code (`LAYOUT_ROW_SERPENTINE`, `ROT_A`, `ROT_B`) If red appears on the right and green appears on the left, flip `CHAIN_STARTS_RIGHT`.

Then open the Serial Monitor, with nothing plugged into the fencing sockets, you should see readings like this

wA=1023 lA=0 wB=1023 lB=0

Power the box from a 5V 2A USB charger.

On startup, the box should:

1. Show the full colour map: white, red, green, white
2. Beep once
3. Run the boot sweep, left to right in this order: white, red, green, white.
4. Enter normal scoring mode

Scoring behaviour:

1. Nothing plugged in: white lights, like a broken weapon wire on a real scoring box
2. Both weapons plugged in and at rest: lights should be off
3. Tip pressed on the floor: white off-target light
4. Tip pressed on the opponent's lame: coloured valid hit light
5. Tip pressed on the opponent's guard: no light
6. Both fencers hit within the lockout window: both lights
7. Very quick tap below the depress time: no light