2. Machine Vibration Monitoring

Capture a short MPU6050 sample window and calculate the root-mean-square deviation from gravity magnitude. Use it only as a repeatable indicator on the same machine.

Level: Advanced · Time: 60 minutes

This is not certified predictive maintenance or safety instrumentation. Mounting, sample rate, machine speed, and resonance strongly affect the result.

Requirements and wiring

ESP32, MPU6050, LED with 220–330 Ω resistor
Adafruit MPU6050, Adafruit Unified Sensor, Adafruit BusIO

Connect SDA→GPIO21, SCL→GPIO22, compatible power→3V3/GND, and the alarm LED to GPIO23 through its resistor.

Complete sketch


#include <PxServ.h>
#include <Wire.h>
#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
 
const char* WIFI_SSID = "your_wifi_ssid";
const char* WIFI_PASSWORD = "your_wifi_password";
const char* PXSERV_API_KEY = "your_pxserv_api_key";
const int ALARM_LED = 23;
const int SAMPLE_COUNT = 100;
const unsigned long SAMPLE_INTERVAL_US = 5000;
 
PxServ client(PXSERV_API_KEY);
Adafruit_MPU6050 mpu;
float alarmThreshold = 2.0;
unsigned long lastMeasurementAt = 0;
 
float measureVibration() {
  float sumSquares = 0;
  for (int i = 0; i < SAMPLE_COUNT; i++) {
    sensors_event_t acceleration, gyro, temperature;
    mpu.getEvent(&acceleration, &gyro, &temperature);
    float magnitude = sqrt(
      acceleration.acceleration.x * acceleration.acceleration.x +
      acceleration.acceleration.y * acceleration.acceleration.y +
      acceleration.acceleration.z * acceleration.acceleration.z
    );
    float dynamicPart = magnitude - 9.81f;
    sumSquares += dynamicPart * dynamicPart;
    delayMicroseconds(SAMPLE_INTERVAL_US);
  }
  return sqrt(sumSquares / SAMPLE_COUNT);
}
 
void setup() {
  Serial.begin(115200);
  pinMode(ALARM_LED, OUTPUT);
  Wire.begin(21, 22);
  if (!mpu.begin()) {
    Serial.println("MPU6050 not found");
    while (true) delay(1000);
  }
  mpu.setAccelerometerRange(MPU6050_RANGE_8_G);
  mpu.setFilterBandwidth(MPU6050_BAND_44_HZ);
  PxServ::connectWifi(WIFI_SSID, WIFI_PASSWORD);
}
 
void loop() {
  if (millis() - lastMeasurementAt < 10000) { delay(20); return; }
  lastMeasurementAt = millis();
 
  PxServ::Callback threshold = client.getData("vibration/alarm-threshold");
  if (threshold.status == 200) alarmThreshold = threshold.data.toFloat();
  float vibration = measureVibration();
  bool alarm = vibration > alarmThreshold;
  digitalWrite(ALARM_LED, alarm ? HIGH : LOW);
  client.setData("vibration/indicator", String(vibration, 3));
  client.setData("vibration/threshold", String(alarmThreshold, 3));
  client.setData("vibration/status", alarm ? "alarm" : "normal");
}

Establish a baseline

Record at least ten stopped and twenty normal-running measurements with identical sensor mounting. Set the threshold above the stable normal range. Never touch or modify a running machine to test an alarm. This half-second metric is not a frequency spectrum.

Reference: Adafruit MPU6050 Arduino guide