// XIAO ESP32-C3 + RCWL-0516 microwave motion sensor
// LED on PWM pin fades up on motion, down after timeout.

const int PIR_PIN  = D10;     // RCWL OUT → D2 (3.3 V logic)
const int LED_PIN  = D10;    // LED+ → D10 through 220 Ω, LED− → GND

const int PWM_CH   = 0;      // LEDC PWM channel
const int PWM_BITS = 8;      // 0..255
const int PWM_FREQ = 5000;   // Hz

const uint8_t FADE_STEP = 5; // brightness step
const uint16_t FADE_DELAY_MS = 3;
const uint32_t HOLD_MS = 5000; // time to wait after last motion

uint32_t lastMotionMs = 0;
uint8_t  target = 0; // 0 or 255
uint8_t  level  = 0;

void setup() {
  pinMode(PIR_PIN, INPUT); // RCWL output is push-pull 3.3 V
  analogWrite(D0,255);
  // ledcSetup(PWM_CH, PWM_FREQ, PWM_BITS);
  // ledcAttachPin(LED_PIN, PWM_CH);
  // ledcWrite(PWM_CH, 0);
}

void loop() {
  if (digitalRead(PIR_PIN) == HIGH) {
    lastMotionMs = millis();
    target = 255;                     // fade up on motion
  } else if (millis() - lastMotionMs > HOLD_MS) {
    target = 0;                       // fade down after inactivity
  }

  // approach target smoothly
  if (level < target) level = min<uint8_t>(255, level + FADE_STEP);
  else if (level > target) level = max<int>(0, level - FADE_STEP);

  // ledcWrite(PWM_CH, level);
  analogWrite(D0,level);
  delay(FADE_DELAY_MS);
}