LD2450 Human Presence Sensor

#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/uart.h"

// LD2450 on UART2: radar TX -> GPIO16 (RX2), RX -> GPIO17 (TX2), 256000 baud
#define RADAR_UART UART_NUM_2
#define RADAR_RX_PIN 16
#define RADAR_TX_PIN 17

// Coordinates are int16 with bit 15 as the sign flag (1 = positive)
static int decode_coord(uint8_t lo, uint8_t hi)
{
    int v = ((hi & 0x7F) << 8) | lo;
    return (hi & 0x80) ? v : -v;
}

void app_main(void)
{
    uart_config_t config = {
        .baud_rate = 256000,
        .data_bits = UART_DATA_8_BITS,
        .parity = UART_PARITY_DISABLE,
        .stop_bits = UART_STOP_BITS_1,
        .flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
    };
    ESP_ERROR_CHECK(uart_param_config(RADAR_UART, &config));
    ESP_ERROR_CHECK(uart_set_pin(RADAR_UART, RADAR_TX_PIN, RADAR_RX_PIN,
                                 UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE));
    ESP_ERROR_CHECK(uart_driver_install(RADAR_UART, 1024, 0, 0, NULL, 0));

    uint8_t frame[28]; // AA FF 03 00 + 3 targets x 8 bytes
    int matched = 0;
    static const uint8_t HEAD[4] = {0xAA, 0xFF, 0x03, 0x00};

    while (1) {
        uint8_t byte;
        if (uart_read_bytes(RADAR_UART, &byte, 1, pdMS_TO_TICKS(100)) != 1)
            continue;
        if (matched < 4) {
            matched = (byte == HEAD[matched]) ? matched + 1 : (byte == HEAD[0]);
            continue;
        }
        frame[0] = byte;
        if (uart_read_bytes(RADAR_UART, &frame[1], 25, pdMS_TO_TICKS(100)) != 25) {
            matched = 0;
            continue;
        }
        matched = 0;
        if (frame[24] != 0x55 || frame[25] != 0xCC)
            continue; // bad tail - resync

        for (int t = 0; t < 3; t++) {
            const uint8_t *d = &frame[t * 8];
            int x = decode_coord(d[0], d[1]);       // mm
            int y = decode_coord(d[2], d[3]);       // mm
            int speed = decode_coord(d[4], d[5]);   // cm/s
            if (x == 0 && y == 0)
                continue; // no target in this slot
            printf("Target %d: X=%d mm, Y=%d mm, speed=%d cm/s\n", t + 1, x, y, speed);
        }
    }
}

uart:
  id: uart_bus
  tx_pin: GPIO17
  rx_pin: GPIO16
  baud_rate: 256000
  parity: NONE
  stop_bits: 1

ld2450:
  id: ld2450_radar
  uart_id: uart_bus

sensor:
  - platform: ld2450
    ld2450_id: ld2450_radar
    target_count:
      name: "Presence Target Count"
    target_1:
      x:
        name: "Target 1 X"
      y:
        name: "Target 1 Y"
      speed:
        name: "Target 1 Speed"
      distance:
        name: "Target 1 Distance"

[env:esp32dev]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
lib_deps =
    rbegamer/HLK-LD2450 @ ^1.1.0

#include <Arduino.h>
#include <LD2450.h>

LD2450 radar;

void setup() {
  Serial.begin(115200);
  Serial2.begin(256000, SERIAL_8N1, 16, 17); // sensor TX -> GPIO16, RX -> GPIO17
  radar.begin(Serial2, true); // serial port is already initialized
}

void loop() {
  if (radar.read() > 0) {
    for (int i = 0; i < radar.getSensorSupportedTargetCount(); i++) {
      LD2450::RadarTarget target = radar.getTarget(i);
      if (!target.valid) continue;
      Serial.print("Target ");
      Serial.print(i);
      Serial.print(": X=");
      Serial.print(target.x);
      Serial.print(" mm, Y=");
      Serial.print(target.y);
      Serial.print(" mm, Distance=");
      Serial.print(target.distance);
      Serial.print(" mm, Speed=");
      Serial.print(target.speed);
      Serial.println(" cm/s");
    }
  }
  delay(500);
}

from machine import UART
import time

uart = UART(2, baudrate=256000, tx=17, rx=16)

while True:
    if uart.any():
        data = uart.read()
        if data:
            print(data)
    time.sleep(0.5)