Ini
[env:esp32dev]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
lib_deps =
  adafruit/DHT sensor library
  plerup/EspSoftwareSerial

Cpp
constexpr int BHA_RX=16, BHA_TX=17;
constexpr int FDA_RX=22, FDA_TX=23;
constexpr int I2S_BCLK=14, I2S_WS=25, I2S_SD=32;
constexpr int MQ2_ADC=34, DHT_PIN=27;
constexpr int XIAO_RX=33, XIAO_TX=13;

Cpp
#include <Arduino.h>
#include <driver/i2s.h>
#include <DHT.h>
#include <SoftwareSerial.h>

constexpr int BHA_RX=16, BHA_TX=17;
constexpr int FDA_RX=22, FDA_TX=23;
constexpr int I2S_BCLK=14, I2S_WS=25, I2S_SD=32;
constexpr int MQ2_ADC=34, DHT_PIN=27;
constexpr int XIAO_RX=33, XIAO_TX=13;

HardwareSerial RadarBHA(1);
HardwareSerial RadarFDA(2);
SoftwareSerial XiaoUart;
DHT dht(DHT_PIN, DHT11);

void setupI2S() {
  i2s_config_t cfg{};
  cfg.mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX);
  cfg.sample_rate = 16000;
  cfg.bits_per_sample = I2S_BITS_PER_SAMPLE_32BIT;
  cfg.channel_format = I2S_CHANNEL_FMT_ONLY_LEFT;
  cfg.communication_format = I2S_COMM_FORMAT_STAND_I2S;
  cfg.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1;
  cfg.dma_buf_count = 4;
  cfg.dma_buf_len = 128;
  cfg.use_apll = false;
  cfg.tx_desc_auto_clear = false;
  cfg.fixed_mclk = 0;
  i2s_pin_config_t pins{I2S_BCLK, I2S_WS, I2S_PIN_NO_CHANGE, I2S_SD};
  i2s_driver_install(I2S_NUM_0, &cfg, 0, nullptr);
  i2s_set_pin(I2S_NUM_0, &pins);
}

void setup() {
  Serial.begin(115200);                 // UART0: laptop debug only
  RadarBHA.begin(1382400, SERIAL_8N1, BHA_RX, BHA_TX);
  RadarFDA.begin(115200, SERIAL_8N1, FDA_RX, FDA_TX);
  XiaoUart.begin(115200, SWSERIAL_8N1, XIAO_RX, XIAO_TX, false);
  analogSetPinAttenuation(MQ2_ADC, ADC_11db);
  dht.begin();
  setupI2S();
}

void loop() {
  // Raw radar pass-through: no undocumented packet interpretation.
  while (RadarBHA.available()) Serial.write(RadarBHA.read());
  while (RadarFDA.available()) Serial.write(RadarFDA.read());
  while (XiaoUart.available()) Serial.write(XiaoUart.read());

  static uint32_t last=0;
  if (millis()-last >= 2000) {
    last=millis();
    int raw=analogRead(MQ2_ADC);
    float t=dht.readTemperature(), h=dht.readHumidity();
    Serial.printf("MQ2 raw=%d DHT11 T=%.1fC RH=%.1f%%\n", raw, t, h);

    int32_t samples[128]; size_t bytes=0;
    if (i2s_read(I2S_NUM_0, samples, sizeof(samples), &bytes, pdMS_TO_TICKS(20))==ESP_OK)
      Serial.printf("I2S bytes=%u first=%ld\n", (unsigned)bytes, (long)samples[0]);
  }
}

1. Power with a current-limited 5 V supply and verify rails.
2. Start UART0 logging.
3. Initialize both hardware UARTs, software UART, ADC, DHT11, then I2S.
4. Confirm raw bytes before adding vendor protocol parsers.
5. Calibrate MQ-2 only after heater burn-in and with an appropriate reference procedure.