Heartbeat Sensor (MW2 Style)

Fan-made, working replica of the Heartbeat Sensor from Call of Duty: Modern Warfare 2. A 24 GHz mmWave radar detects people, and the 1.8" screen shows them as red blips on the classic radar fan with a sweeping pulse – just like in the game. The Pico W opens its own Wi-Fi hotspot, so you can change all settings from your phone.

FEATURES

• Pulse sweep like in the game – targets light up and fade (or continuous live mode)

• 4 colour themes: MW2 classic cyan, night vision green, amber, thermal

• Range 1.5–11 m, metric or imperial units, English/German interface

• Phone settings page with live radar view (opens automatically, no app or internet needed)

• Battery level, USB-C charging, demo mode with simulated enemies

• Rugged case: armoured corners with screws, recessed screen, ▲ ▼ MENU / POWER panel, side mount (2× M3, 20 mm spacing) for a rail adapter

PRINTED PARTS (no supports needed)

• Rear housing – print with the back on the bed

• Front cover – print with the inside on the bed (front facing up)

• Pico clamp – print flat

PLA or PETG, 0.2 mm layers, 4 walls (for the heat-set inserts), 20–25 % infill.

IMPORTANT: set the bottom thickness to at least 4 mm (e.g. 20 bottom layers). The wall in front of the radar is 3.8 mm thick (about half a wavelength in PLA at 24 GHz) and must be printed solid so the radar can see through it.

HARDWARE

• Raspberry Pi Pico W with pin headers

• 1.8" SPI TFT 128×160 (ST7735, e.g. AZ-Delivery)

• Waveshare HMMD mmWave sensor 24 GHz

• TC4056 USB-C charger board with protection

• 3.7 V 1000 mAh LiPo (fits 44×26×10 and 40×30×8 mm)

• Round rocker switch for a 20 mm panel hole

• 7× M3 heat-set inserts (3.8 mm holes)

• 4× M3×8–12 + 1× M3×6–8 socket head screws

• Female-female jumper wires, 20 cm

• Recommended: 1N5817 Schottky diode (stops USB power from back-feeding into the battery)

WIRING (Pico W pin numbers)

Display: VCC + LED → 3V3 (36), GND → 23, CS → GP17 (22), RESET → GP20 (26), A0/DC → GP16 (21), SDA → GP19 (25), SCK → GP18 (24)

Radar: 3V3 → 3V3 (36), GND → 3, TX → GP1 (2), RX → GP0 (1), OT2 → GP2 (4)

Power: battery → TC4056 B+/B−, OUT+ → rocker switch → diode → VSYS (39), OUT− → GND (38)

The Pico has only one 3V3 pin, so solder a small Y-splice for the display and the radar.

FIRMWARE

Arduino IDE with the "Raspberry Pi Pico/RP2040" board package (Earle Philhower), board "Raspberry Pi Pico W". Libraries: Adafruit ST7735 and ST7789, Adafruit GFX, ArduinoJson 7.

After switching on, connect your phone to the Wi-Fi "HBS-MW2" (password "heartbeat"). The settings page opens automatically, otherwise go to http://192.168.4.1

GOOD TO KNOW

The radar measures distance only, not direction. The dots hint at a direction like the jitter in the game. Switch to "distance arcs" in the settings for an honest display.

Fan art – not affiliated with or endorsed by Activision or Infinity Ward.