ESP32 Vibration Monitor

// ESP32 Vibration Monitor - Intermediate (RMS + peak frequency + web chart)
#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
#include <WiFi.h>
#include <WebServer.h>
#include <Adafruit_SSD1306.h>
#include <arduinoFFT.h>

const char* SSID="YourSSID", *PASS="YourPass";
Adafruit_MPU6050 mpu;
Adafruit_SSD1306 oled(128,64,&Wire,-1);
WebServer server(80);

const int SAMPLES=256;
double vReal[SAMPLES], vImag[SAMPLES];
ArduinoFFT<double> FFT=ArduinoFFT<double>(vReal,vImag,SAMPLES,500.0);

float rmsHistory[60]={0}; // 1-minute rolling buffer
int   histIdx=0;
float currentRMS=0, peakFreq=0;

float computeRMS(){
  float sum=0;
  sensors_event_t a,g,t;
  for(int i=0;i<SAMPLES;i++){
    mpu.getEvent(&a,&g,&t);
    float mag=sqrt(a.acceleration.x*a.acceleration.x+
                   a.acceleration.y*a.acceleration.y+
                   a.acceleration.z*a.acceleration.z)-9.81f;
    vReal[i]=mag; vImag[i]=0;
    sum+=mag*mag;
    delayMicroseconds(2000); // 500 Hz
  }
  FFT.windowing(FFT_WIN_TYP_HAMMING,FFT_FORWARD);
  FFT.compute(FFT_FORWARD);
  FFT.complexToMagnitude();
  peakFreq=FFT.majorPeak();
  return sqrt(sum/SAMPLES);
}

void setup(){
  Serial.begin(115200);
  Wire.begin(21,22);
  mpu.begin(); mpu.setAccelerometerRange(MPU6050_RANGE_8_G);
  oled.begin(SSD1306_SWITCHCAPVCC,0x3C);
  oled.setTextSize(1); oled.setTextColor(WHITE);
  WiFi.begin(SSID,PASS);
  while(WiFi.status()!=WL_CONNECTED) delay(500);
  server.on("/",[](){
    String body="<h2>Vibration Monitor</h2><p>RMS: "+String(currentRMS,3)+
      " m/s2 | Peak: "+String(peakFreq,1)+" Hz</p>";
    body+="<canvas id=c width=600 height=200></canvas><script>"
      "var d=[";
    for(int i=0;i<60;i++) body+=String(rmsHistory[(histIdx+i)%60])+",";
    body+="];"
      "var c=document.getElementById("c").getContext("2d");"
      "c.beginPath();"
      "for(var i=0;i<d.length;i++){c.lineTo(i*10,200-d[i]*20);}"
      "c.stroke();</script>";
    server.send(200,"text/html",body);
  });
  server.begin();
}

void loop(){
  currentRMS=computeRMS();
  rmsHistory[histIdx%60]=currentRMS;
  histIdx++;

  oled.clearDisplay(); oled.setCursor(0,0);
  oled.printf("RMS: %.3f m/s2n",currentRMS);
  oled.printf("Peak: %.1f Hzn",peakFreq);
  // ISO 10816 Zone A < 0.71, B < 1.8, C < 4.5, D >= 4.5 mm/s
  oled.println(currentRMS<0.71?"Zone A OK":currentRMS<1.8?"Zone B GOOD":
               currentRMS<4.5?"Zone C WARN":"Zone D ALARM");
  oled.display();
  digitalWrite(15, currentRMS>=4.5?HIGH:LOW);
  server.handleClient();
}