Servo gate or pet feeder

/*
  09 — Servo gate or pet feeder
  Board: ESP32.  Parts: SG90 servo, tactile switch (optional trigger).
  Library: "ESP32Servo" (the standard Servo library does not support the ESP32).

  Wiring:
    SG90:   brown -> GND, red -> VIN (5 V), orange (signal) -> GPIO 13
            Power it from the 5 V pin, never from a GPIO: a small servo can pull
            more than a pin can give, and a browning-out board that resets
            mid-move is the classic first failure here.
    Button: one leg -> GPIO 27, other leg -> GND (press = open the gate now)

  The SG90 HOLDS an angle rather than spinning: a 1–2 ms pulse every 20 ms
  sets the position. That is what makes it a gate, a dispenser or a valve.
*/

#include <ESP32Servo.h>

const int SERVO_PIN  = 13;
const int BUTTON_PIN = 27;

const int CLOSED_DEG = 10;
const int OPEN_DEG   = 100;
const unsigned long OPEN_FOR_MS   = 1500;    // how long the gate stays open
const unsigned long FEED_EVERY_MS = 6UL * 60UL * 60UL * 1000UL;   // 6 h timer (0 = button only)

Servo gate;
unsigned long lastFeed = 0;

void openGate() {
  Serial.println("open");
  for (int a = CLOSED_DEG; a <= OPEN_DEG; a += 2) { gate.write(a); delay(10); }   // slow = quiet
  delay(OPEN_FOR_MS);
  for (int a = OPEN_DEG; a >= CLOSED_DEG; a -= 2) { gate.write(a); delay(10); }
  Serial.println("closed");
}

void setup() {
  Serial.begin(115200);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  gate.setPeriodHertz(50);              // standard 50 Hz servo signal
  gate.attach(SERVO_PIN, 500, 2400);    // SG90 pulse range in microseconds
  gate.write(CLOSED_DEG);
  lastFeed = millis();
}

void loop() {
  if (digitalRead(BUTTON_PIN) == LOW) {          // manual trigger
    openGate();
    lastFeed = millis();
    delay(300);                                  // crude debounce, fine here
  }
  if (FEED_EVERY_MS > 0 && millis() - lastFeed >= FEED_EVERY_MS) {
    openGate();
    lastFeed = millis();
  }
}