Firmware for a Seeed XIAO ESP32-C6 driving a C4001 24GHz radar, with a
web UI for live data and calibration.
- Auto-detects whether the C4001 is on I2C (0x2A/0x2B) or UART, so the
board's mode switch position doesn't matter. Serves the probe log over
HTTP when nothing is found.
- Single-page UI inlined into flash (no CDN, so it works in AP mode):
presence state, target count, range, speed, energy, rolling 60s chart,
and mode-aware calibration controls.
- Joins WiFi from a gitignored include/secrets.h, falls back to a
"xiao-mmwave" AP, registers mmwave.local.
- Poll rate adapts to the interface: UART at 9600 costs ~60ms per register
round-trip, so polling it at the I2C rate starved the HTTP server.
Two hardware gotchas documented in the README:
- The sensor UART must not use D6/D7. Those are GPIO16/17, the C6's
hard-wired U0TXD/U0RXD. Pointing Serial1 at them deadlocks the UART
driver and trips the interrupt watchdog, boot-looping the board. UART1
has no fixed pins, so it routes through the GPIO matrix to D10/D9.
- DFRobot's own wiring table pairs the sensor's RX with the MCU's RX, and
their library swaps the rxpin/txpin parameter names between the header
and the .cpp.
Verified on ESP32-C6FH4 rev v0.1, 4MB flash: builds at 57.6% flash /
11.9% RAM, flashes over the native USB Serial/JTAG port, and reads a live
C4001 on I2C @ 0x2A.
Co-Authored-By: Claude <noreply@anthropic.com>
