Sensor Commands

LD2450 mmWave Radar

The LD2450 is a 24 GHz mmWave presence/target radar connected to the ESP32 over UART (256000 8N1). The firmware parses the standard 30-byte target frame and exposes up to three targets with X/Y position, speed, and range resolution.

Command	Args	Response	Notes
LD2450_SET_CONFIG	{rx_gpio:int, tx_gpio:int}	{ok, msg, configured, rx_pin, tx_pin, ld2450_rx_gpios:[...], ld2450_tx_gpios:[...]} plus status fields	Validates target-safe, distinct UART pins, stops the driver, persists them in ESP32 NVS, and reports the saved configuration.
LD2450_START	{debug?:bool=false}	{ok:true, active, debug, valid_frames, invalid_frames, dropped_bytes, target_count, presence, has_data, last_frame_ms, last_frame_age_ms, baud, rx_pin, tx_pin, configured, ld2450_rx_gpios:[...], ld2450_tx_gpios:[...]}	Starts/restarts the UART driver using the saved RX/TX pins. debug is off by default in app/protocol mode; enable it only for standalone serial bring-up.
LD2450_STOP	none	{ok:true, active:false, ...}	Stops parsing and clears the live target list.
LD2450_STATUS	none	{ok:true, active, debug, valid_frames, invalid_frames, dropped_bytes, target_count, presence, has_data, last_frame_ms, last_frame_age_ms, baud, rx_pin, tx_pin, configured, ld2450_rx_gpios:[...], ld2450_tx_gpios:[...]}	Returns current driver, GPIO configuration, safe GPIO choices, and frame counters.

Events emitted while active:

• ld2450_targets — one event per valid 30-byte frame.
• ld2450_presence — target-present / target-lost transition.
• ld2450_error — parse errors or no-data timeout.

Sign convention

X/Y/speed use bit 15 plus 15-bit magnitude, not two's-complement:

• bit 15 = 1 -> positive magnitude
• bit 15 = 0 -> negative magnitude

Coordinates are millimetres, speed is cm/s, resolution is millimetres. The corrected firmware follows the reference ESPHome/HLK-LD2450 decoder.

The LD2450 requires a stable 5 V supply unless the carrier explicitly supports 3.3 V. UART logic is 3.3 V-compatible. RX/TX must be crossed to the ESP32 (sensor TX -> ESP32 RX, sensor RX -> ESP32 TX) and must not share the ESP32 UART0 pins used by the USB-UART bridge.