The simple harmonic model measures the period, acceleration due to gravity, and angular velocity.

#define BUTTON 34
#define SENSOR 23
#define MAGNETIC 27
 
float previousTimer = 0.000f;
float timer[2] = {0.000f};
int count = 0;
bool statusSensor = false;
bool firstTime = true;
bool buttonPressed = false;
char messageT[75];
bool check = false;
 
const char ssid[] = "ssid";
const char pass[] = "pass";
 
const char mqtt_broker[]="test.mosquitto.org";
const char mqtt_topic[]="####";
const char mqtt_client_id[]="####";
int MQTT_PORT=1883;
 
WiFiClient net;
MQTTClient client;
 
void connect() {
  Serial.print("checking wifi...");
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print(".");
    delay(1000);
  }
 
  Serial.print("\nconnecting...");
  while (!client.connect(mqtt_client_id)) {  
    Serial.print(".");
    delay(1000);
  }
 
  Serial.println("\nconnected!");
 
  client.subscribe(mqtt_topic);
  // client.unsubscribe("/hello");
}
 
void messageReceived(String &topic, String &payload) {
  Serial.println("incoming: " + topic + " - " + payload);
  if(payload == "pushButton"){
    digitalWrite(MAGNETIC, HIGH);
    delay(100);
    digitalWrite(MAGNETIC, LOW);
  }
}
 
void setup() {
  // ปุ่มปล่อยแม่เหล็ก
  pinMode(BUTTON, INPUT);
  // sensor ตรวจจับ
  pinMode(SENSOR, INPUT);
  // แม่เหล็ก
  pinMode(MAGNETIC, OUTPUT);
  digitalWrite(MAGNETIC, LOW);
  WiFi.begin(ssid, pass);
  Serial.begin(9600);
  client.begin(mqtt_broker, MQTT_PORT, net);
  client.onMessage(messageReceived);
 
  connect();
  lcd.begin();
  lcd.backlight();
 
  lcd.print("Group2.11");
}
 
void loop() {
  client.loop();
  if (!client.connected()) {
    connect();
  }
 
  // จับเวลาและหยุดจับเวลา
  if(digitalRead(SENSOR) == 0 && !statusSensor){
    if (firstTime) {
      firstTime = false;
    } else {
      timer[count] = millis() - timer[count]; // หยุดจับเวลา
      count++;
      if (count == 2) {
        count = 0;
        // ตรวจสอบค่า timer
        bool validData = true;
        for (int i = 0; i < 2; i++) {
          if (timer[i] < 200.000f) {
            validData = false;
            break;
          }
        }
        if (validData) {
          // คำนวณค่า timer เฉลี่ย
          float averageTimer = 0.000f;
          for (int i = 0; i < 2; i++) {
            averageTimer += timer[i];
          }
          averageTimer /= 2.000f;
          // คำนวณค่า g เฉลี่ย
          double g = 0.0;
          double T = 0.0;
          double W = 0.0;
          for (int i = 0; i < 2; i++) {
            g += 4 * PI * PI * (0.09 / ((timer[i] / 500.0) * (timer[i] / 500.0)));
          }
          g /= 2.0;
          W = sqrt(g/0.09);
          lcd.setCursor(0, 1);
          // แสดงผลลัพธ์
          if( g > 8.5){
            lcd.clear();
            lcd.print("T: ");
            lcd.print(averageTimer/500.000);
            lcd.print(" s");
            lcd.setCursor(0, 2);
            lcd.print("g: ");
            lcd.print(g);
            lcd.print(" m/s^2");
 
            Serial.println();
            Serial.print("T: ");
            Serial.print(averageTimer/500.000);
            Serial.println(" s");
            Serial.print("g: ");
            Serial.print(g);
            Serial.println(" m/s^2");
            Serial.print("w: ");
            Serial.print(W);
            Serial.println(" rad/s");
            sprintf(messageT, "T: %.3f s __ g: %.2f m/s^2 __ w: %.2f rad/s", averageTimer/500.0 , g, W);
            client.publish(mqtt_topic, messageT);
          }
        }
      }
    }
    timer[count] = millis(); // เริ่มจับเวลา
    statusSensor = true;
  }
  if(digitalRead(SENSOR) == 1 && statusSensor){
    statusSensor = false;
  }
}

#define MAGNETIC 27
#define BUTTON 34
#define LED 21
 
float previousTimer = 0.000f;
float timer[2] = {0.000f};
int count = 0;
bool statusSensor = false;
bool firstTime = true;
bool buttonPressed = false;
char messageT[50];
bool check = false;
 
void setup() {
  pinMode(BUTTON, INPUT);
  pinMode(MAGNETIC, OUTPUT);
  digitalWrite(MAGNETIC, HIGH);
  pinMode(LED, OUTPUT);
  digitalWrite(LED,HIGH);
}
 
void loop() {
  if (digitalRead(BUTTON) == HIGH && !buttonPressed) {
    buttonPressed = true;
    digitalWrite(MAGNETIC, LOW);
    digitalWrite(LED,LOW);
    while(buttonPressed){
      
      delay(310);
      digitalWrite(MAGNETIC, HIGH);
      digitalWrite(LED,HIGH);
      delay(300);
      digitalWrite(MAGNETIC, LOW);
      digitalWrite(LED, LOW);
      
    }
  }
  if (digitalRead(BUTTON) == LOW && buttonPressed) {
    buttonPressed = false;
    digitalWrite(MAGNETIC, HIGH);
    digitalWrite(LED,LOW);
  }
}