• MCU: ESP32-S3-MINI-1U-N8
• Framework: Arduino on PlatformIO
• Programming: USB-C native USB Serial/JTAG / ROM downloader using BOOT + RESET

Ini
[env:esp32-s3]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600
build_flags =
  -DARDUINO_USB_MODE=1
  -DARDUINO_USB_CDC_ON_BOOT=1

Cpp
#include <Arduino.h>
#include <Wire.h>
#include <WiFi.h>

#define RELAY_SET_PIN        4
#define RELAY_RESET_PIN      5
#define LED_WIFI_PIN         6
#define LED_RELAY_PIN        7
#define I2C_SCL_PIN          8
#define I2C_SDA_PIN          9
#define ACS_FAULT_PIN        10
#define ADC_CURRENT_PIN      1
#define ADC_AC_VOLTAGE_PIN   2

#define TMP102_ADDR          0x48
#define RELAY_PULSE_MS       50
#define SAMPLE_INTERVAL_MS   1000

const char* WIFI_SSID = "YOUR_SSID";
const char* WIFI_PASSWORD = "YOUR_PASSWORD";

bool relayOn = false;
uint32_t lastSample = 0;

void pulseRelay(bool turnOn) {
  const int pin = turnOn ? RELAY_SET_PIN : RELAY_RESET_PIN;
  digitalWrite(pin, HIGH);
  delay(RELAY_PULSE_MS);
  digitalWrite(pin, LOW);
  relayOn = turnOn;
  digitalWrite(LED_RELAY_PIN, relayOn ? HIGH : LOW);
}

bool readTMP102(float &tempC) {
  Wire.beginTransmission(TMP102_ADDR);
  Wire.write(0x00);
  if (Wire.endTransmission(false) != 0) return false;
  if (Wire.requestFrom(TMP102_ADDR, 2) != 2) return false;
  int16_t raw = (Wire.read() << 4) | (Wire.read() >> 4);
  if (raw & 0x800) raw |= 0xF000;
  tempC = raw * 0.0625f;
  return true;
}

float readAdcVolts(int pin) {
  uint16_t raw = analogRead(pin);
  return (raw / 4095.0f) * 3.3f;
}

float estimateLoadCurrentA() {
  float vadc = readAdcVolts(ADC_CURRENT_PIN);
  float sensorVout = vadc * 1.5f;       // R22=10k, R23=20k divider
  return (sensorVout - 2.5f) / 0.050f;  // ACS732-40AB: 50 mV/A typ
}

float readAcVoltageAdcVolts() {
  return readAdcVolts(ADC_AC_VOLTAGE_PIN); // Calibration required for RMS mains voltage
}

void initWiFi() {
  WiFi.mode(WIFI_STA);
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  uint8_t tries = 0;
  while (WiFi.status() != WL_CONNECTED && tries++ < 20) {
    digitalWrite(LED_WIFI_PIN, !digitalRead(LED_WIFI_PIN));
    delay(250);
  }
  digitalWrite(LED_WIFI_PIN, WiFi.status() == WL_CONNECTED ? HIGH : LOW);
}

void setup() {
  Serial.begin(115200);
  delay(300);
  pinMode(RELAY_SET_PIN, OUTPUT);
  pinMode(RELAY_RESET_PIN, OUTPUT);
  pinMode(LED_WIFI_PIN, OUTPUT);
  pinMode(LED_RELAY_PIN, OUTPUT);
  pinMode(ACS_FAULT_PIN, INPUT_PULLUP);
  digitalWrite(RELAY_SET_PIN, LOW);
  digitalWrite(RELAY_RESET_PIN, LOW);
  digitalWrite(LED_RELAY_PIN, LOW);
  analogReadResolution(12);
  Wire.begin(I2C_SDA_PIN, I2C_SCL_PIN);
  initWiFi();
  Serial.println("ESP32-S3 IoT Relay Controller ready");
}

void loop() {
  if (millis() - lastSample >= SAMPLE_INTERVAL_MS) {
    lastSample = millis();
    float tempC = NAN;
    bool tempOk = readTMP102(tempC);
    float currentA = estimateLoadCurrentA();
    float acAdc = readAcVoltageAdcVolts();
    bool fault = digitalRead(ACS_FAULT_PIN) == LOW;
    Serial.printf("relay=%d temp=%s%.2fC current=%.2fA ac_adc=%.3fV fault=%d wifi=%d\n",
      relayOn, tempOk ? "" : "ERR ", tempOk ? tempC : NAN, currentA, acAdc, fault, WiFi.status() == WL_CONNECTED);
    if (fault || (tempOk && tempC > 85.0f)) {
      pulseRelay(false);
      Serial.println("Safety trip: relay reset");
    }
  }
  if (WiFi.status() != WL_CONNECTED) initWiFi();
}

Bash
pio run
pio run -t upload
pio device monitor