Reference Electronics

The shared light-gun hardware design: MCU, IR camera, inputs, solenoid and rumble drivers, the screen LED bar, a proposed schematic and a full BOM.

Firearms

Reference Electronics · Deep Dive

Reference Electronics

One board design for every build that follows.

The shared light-gun hardware design: MCU, IR camera, inputs, solenoid and rumble drivers, the screen LED bar, a proposed schematic and a full BOM.

Photo: DFRobot SEN0158 IR positioning camera by DFRobot

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    Volumes

    1. Vol 1 System Architecture — What the Board Has to Do, and Why One USB light gun, five electrical domains, and the requirements the OpenFIRE firmware fixes before a single trace is drawn
    2. Vol 2 The Microcontroller Board — Pico, Pico 2 and the Alternatives Which boards the firmware actually supports, the pin map it expects, the I2C and SPI pin rules, a silicon erratum that changes a pull-down resistor, and what to buy
    3. Vol 3 The IR Positioning Camera — Module, Bus, Mounting and Field of View The DFRobot SEN0158 every guide names and nobody can buy from DFRobot, the Wii sensor kept as a bench stopgap, the PixArt PAJ7025R3 chosen for kits, and the arithmetic of seeing four dots
    4. Vol 4 Inputs — Switches, a Hall-Effect Trigger, Debounce and the Harness How a Hall-effect trigger, a dozen buttons and a temperature sensor are wired into a gun, what the firmware already does about bounce, which Hall sensor and magnet, and the low-power one that would make a trigger 200 ms late
    5. Vol 5 Output Stages — Solenoid and Rumble Drivers, Clamps and LEDs Why the usual MOSFET is out of its datasheet at 3.3 V, a regulated-current stage for the carrier, where the TVS goes, why two stages never fire together, and the small parts that keep a solenoid from firing on its own
    6. Vol 6 The Screen IR Emitter Bar — Wavelength, Current and Layout 940 or 850 nm, what \"SFH 4547 with 5.6 Ω\" actually means, and a constant-current bar that does not care which LED or which adapter it gets
    7. Vol 7 Breadboard Bring-Up — What to Measure, With What, and What Counts as a Pass A staged plan for the first bench build: one electrical domain at a time, with the test points, instruments and pass criteria that turn this dive's open numbers into measured ones
    8. Vol 8 The Carrier Board and the Custom PCB — Proposed Schematic and Notes for Altium Stage 1, a Pico on a four-layer carrier board inside an MP7 with regulated solenoid stages and two camera options, its cable leaving through the magazine base plate, net by net; Stage 2, the custom board, kept as notes for later
    9. Vol 9 Bill of Materials — Part Numbers, Sources and Dated Prices The breadboard kit, the reference carrier board and the emitter bar, every line with its manufacturer part number and, where a seller's page could be read, a price dated 2026-10-18