Build Order¶

The hardware has genuine prerequisites. Each step below assumes the previous one is done and verified — the point of the order is that when something breaks, only one thing changed.

0. Order the parts¶

→ Parts list

Some items ship slowly. Order everything before you start, including the R17 resistor (47 kΩ, and a 33 kΩ as backup) for the sound detector.

1. Wire the sound trigger¶

→ Sound trigger wiring

Solder the R17 gain resistor, then wire GATE → HOST_INT and the shared ground. This is the one soldering job in the build.

Verify: the GATE LED flashes when you clap and goes out again. If it stays lit, fit a lower-value R17.

2. Set up the Raspberry Pi¶

→ Raspberry Pi setup

Install the OS and dependencies, run the setup script.

Verify: the server starts in mock mode — scripts/start-kiosk.sh --mock.

3. Persist rolling-buffer mode¶

→ Rolling buffer setup

One time, per radar. The OPS243 must hold rolling-buffer mode in flash or hardware triggers will not work.

Verify: test_rolling_buffer_persist.py --test reports triggers when you clap.

4. Move the OPS243 to the GPIO UART¶

→ OPS243 → GPIO UART

Required before the IWR6843, which needs the USB bus and real current. Do this migration on its own; adding the TI radar at the same time makes any failure ambiguous.

Verify: the diagnostic reports 230400 baud and roughly 22 KB/s. A pass reporting 19,200 is treated as a failure on purpose — it means the radar never received the I5 command, so check the Pi pin 8 → J3 pin 6 wire.

5. Add the IWR6843 angle radar¶

→ IWR6843 operator guide

The largest step, and itself ordered: wiring → flashing → mounting and geometry → start and verify.

Verify: the first capture returns a sane launch angle.

Optional extras¶

Any order, once the above works.

When something does not work¶

Start at the troubleshooting symptom index, which routes by what you are seeing rather than by which component you suspect.