Sentinel: Industry 4.0 Smart Monitoring Node

A distributed industrial gateway leveraging dual-node processing and alpha-filtering for high-speed mechanical health monitoring. Bridging the gap between raw sensor data and actionable intelligence through a responsive HMI and remote WiFi dashboard.

May 20, 2026

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GPL3+

Data Collection

Internet Of Things

Monitoring

Devices & Components

Arduino USB 2.0 CABLE TYPE A/B 1M

BMP280 Module

USB to micro USB cable

Espressif ESP32 S3 BOX 3

DHT11 Temp Sensor

Raspberry Pi Pico

Medium breadboard

MPU6050 Module

Jumper Wires

Software & Tools

Arduino IDE

Project description

Code

ESP32-S3-BOX3 Node

cpp

Code for ESP32-S3-BOX3 Node (Check GitHub Repo)

1/*
2* Project Name: Sentinel
3* Designed For: ESP32 S3 BOX 3
4*
5*
6* License: GPL3+
7* This project is licensed under the GNU General Public License v3.0 or later.
8* You are free to use, modify, and distribute this software under the terms
9* of the GPL, as long as you preserve the original license and credit the original
10* author. For more details, see <https://www.gnu.org/licenses/gpl-3.0.en.html>.
11*
12* Copyright (C) 2026 Ameya Angadi
13*
14* Code Created And Maintained By: Ameya Angadi
15* Last Modified On: March 30, 2026
16* Version: 1.0.0
17*
18*/
19
20#include <Arduino.h>
21#include <WiFi.h>
22#include <WebServer.h>
23#include <time.h>
24#include <Preferences.h>
25#include <esp_display_panel.hpp>
26#include <lvgl.h>
27#include <ui.h>
28#include "lvgl_v8_port.h"
29
30using namespace esp_panel::drivers;
31using namespace esp_panel::board;
32
33// --- CONFIGURATION ---
34const char* ssid = "";
35const char* password = "";
36#define RXD1 40
37#define TXD1 41
38
39WebServer server(80);
40Preferences prefs;
41Board *board = nullptr;
42
43// Global Data
44float g_temp = 0, g_hum = 0, g_pres = 0;
45float g_x = 0, g_y = 0, g_z = 0, g_vibe = 0;
46String g_status = "WAITING";
47String g_last_maint = "01/01/2026";
48String g_next_maint = "01/07/2026";
49int currentBrightness = 100;
50unsigned long lastWifiCheck = 0;
51
52// Web Server Background Color Logic (Vibrant Shades)
53void handleRoot() {
54String bg = "#1a1a1a"; // Dark Gray (default)
55if (g_status == "DANGER") bg = "#ff4b2b"; // Vibrant Safety Red
56else if (g_status == "CAUTION") bg = "#ff9800"; // Vibrant Safety Orange
57
58String html = "<html><head><style>";
59html += "body { font-family: 'Segoe UI', sans-serif; background: " + bg + "; color: white; padding: 25px; margin: 0; transition: background 0.4s; }";
60html += ".card { background: rgba(0,0,0,0.75); padding: 30px; border-radius: 20px; border: 1px solid rgba(255,255,255,0.2); max-width: 450px; margin: auto; box-shadow: 0 10px 30px rgba(0,0,0,0.5); }";
61html += "h2 { margin: 0; text-transform: uppercase; letter-spacing: 2px; text-shadow: 2px 2px 4px rgba(0,0,0,0.5); }";
62html += ".metric { margin: 18px 0; border-bottom: 1px solid rgba(255,255,255,0.1); padding-bottom: 10px; }";
63html += ".val { font-weight: bold; font-size: 1.6em; color: white; }";
64html += ".label { color: #bbb; display: block; font-size: 0.85em; text-transform: uppercase; margin-bottom: 5px; }";
65html += "</style></head><body><div class='card'>";
66html += "<h2>SYSTEM " + g_status + "</h2><br>";
67
68html += "<div class='metric'><span class='label'>Vibration Intensity</span><span class='val'>" + String(g_vibe) + " G</span></div>";
69html += "<div class='metric'><span class='label'>Temperature</span><span class='val'>" + String(g_temp) + " C</span></div>";
70html += "<div>" + String(g_hum) + "% Humidity | " + String(g_pres) + " hPa</div><br>";
71html += "<div style='font-size: 0.8em; color: #aaa;'>Service: " + g_last_maint + " | Due: " + g_next_maint + "</div>";
72html += "</div></body></html>";
73server.send(200, "text/html", html);
74}
75
76// --- EVENT HANDLERS ---
77
78void onBrightnessChange(lv_event_t * e) {
79lv_obj_t * slider = lv_event_get_target(e);
80int val = lv_slider_get_value(slider);
81if (val < 10) val = 10;
82currentBrightness = val;
83board->getBacklight()->setBrightness(currentBrightness);
84}
85
86void updateSettingsScreenUI() {
87if (millis() - lastWifiCheck > 2000) {
88lastWifiCheck = millis();
89String ssidStr = WiFi.SSID();
90if(ssidStr.isEmpty()) ssidStr = "Searching...";
91lv_label_set_text(ui_LabelWifiSSID, ("SSID: " + ssidStr).c_str());
92
93if (WiFi.status() == WL_CONNECTED) {
94lv_label_set_text(ui_LabelWifiStatus, "Status: Connected");
95lv_obj_set_style_text_color(ui_LabelWifiStatus, lv_color_hex(0x00FF00), 0);
96} else {
97lv_label_set_text(ui_LabelWifiStatus, "Status: Disconnected");
98lv_obj_set_style_text_color(ui_LabelWifiStatus, lv_color_hex(0xFF0000), 0);
99}
100}
101}
102
103void onMaintBtnClicked(lv_event_t * e) {
104struct tm info;
105if (getLocalTime(&info)) {
106char buf[15];
107strftime(buf, sizeof(buf), "%d/%m/%Y", &info);
108g_last_maint = String(buf);
109info.tm_mon += 6;
110mktime(&info);
111strftime(buf, sizeof(buf), "%d/%m/%Y", &info);
112g_next_maint = String(buf);
113
114prefs.begin("maint", false);
115prefs.putString("last", g_last_maint);
116prefs.putString("next", g_next_maint);
117prefs.end();
118
119lv_label_set_text(ui_LabelLastMaintainaceDate, g_last_maint.c_str());
120lv_label_set_text(ui_LabelNextMaintDate, g_next_maint.c_str());
121}
122}
123
124void setup() {
125Serial.begin(115200);
126Serial1.begin(115200, SERIAL_8N1, RXD1, TXD1);
127Serial1.setTimeout(50);
128
129board = new Board();
130board->init();
131assert(board->begin());
132lvgl_port_init(board->getLCD(), board->getTouch());
133
134lvgl_port_lock(-1);
135ui_init();
136
137if(ui_ButtonUpdateMaint) lv_obj_add_event_cb(ui_ButtonUpdateMaint, onMaintBtnClicked, LV_EVENT_CLICKED, NULL);
138
139if (ui_SliderBrightness) {
140lv_slider_set_range(ui_SliderBrightness, 10, 100);
141lv_slider_set_value(ui_SliderBrightness, 100, LV_ANIM_OFF);
142lv_obj_add_event_cb(ui_SliderBrightness, onBrightnessChange, LV_EVENT_VALUE_CHANGED, NULL);
143}
144
145prefs.begin("maint", true);
146g_last_maint = prefs.getString("last", "01/01/2026");
147g_next_maint = prefs.getString("next", "01/07/2026");
148prefs.end();
149
150lv_label_set_text(ui_LabelLastMaintainaceDate, g_last_maint.c_str());
151lv_label_set_text(ui_LabelNextMaintDate, g_next_maint.c_str());
152lvgl_port_unlock();
153
154WiFi.begin(ssid, password);
155server.on("/", handleRoot);
156server.begin();
157configTime(19800, 0, "pool.ntp.org");
158}
159
160void loop() {
161server.handleClient();
162static unsigned long lastClock = 0;
163struct tm timeinfo;
164
165if (lv_scr_act() == ui_SettingScreen) {
166lvgl_port_lock(-1);
167updateSettingsScreenUI();
168lvgl_port_unlock();
169}
170
171if (Serial1.available() > 0) {
172String raw = Serial1.readStringUntil('\n');
173if (raw.startsWith("$[")) {
174String data = raw.substring(raw.indexOf("$[") + 2, raw.indexOf("]"));
175float v[7]; int count = 0;
176char* ptr = strtok((char*)data.c_str(), ",");
177while (ptr != NULL && count < 7) { v[count++] = atof(ptr); ptr = strtok(NULL, ","); }
178
179if (count == 7) {
180g_temp = v[0]; g_hum = v[1]; g_pres = v[2];
181g_x = v[3]; g_y = v[4]; g_z = v[5]; g_vibe = v[6];
182
183lvgl_port_lock(-1);
184uint32_t s_color = 0x00FF00;
185if (g_temp > 55.0 || g_vibe > 0.70) { g_status = "DANGER"; s_color = 0xFF0000; }
186else if (g_temp > 42.0 || g_vibe > 0.15) { g_status = "CAUTION"; s_color = 0xFFA500; }
187else { g_status = "HEALTHY"; s_color = 0x00FF00; }
188
189lv_label_set_text(ui_LabelHealthStatus, g_status.c_str());
190lv_obj_set_style_text_color(ui_LabelHealthStatus, lv_color_hex(s_color), 0);
191
192char b[16];
193snprintf(b, sizeof(b), "%.1f C", g_temp);
194lv_label_set_text(ui_LabelTemp, b); lv_label_set_text(ui_LabelTempES, b);
195
196snprintf(b, sizeof(b), "%.0f %%", g_hum);
197lv_label_set_text(ui_LabelHum, b); lv_label_set_text(ui_LabelHumES, b);
198
199snprintf(b, sizeof(b), "%.1f hPa", g_pres); lv_label_set_text(ui_LabelBMPressure, b);
200snprintf(b, sizeof(b), "X: %.2f G", g_x); lv_label_set_text(ui_LabelXaxis, b);
201snprintf(b, sizeof(b), "Y: %.2f G", g_y); lv_label_set_text(ui_LabelYaxis, b);
202snprintf(b, sizeof(b), "Z: %.2f G", g_z); lv_label_set_text(ui_LabelZaxis, b);
203snprintf(b, sizeof(b), "%.2f G", g_vibe); lv_label_set_text(ui_LabelCombinedMPU, b);
204lvgl_port_unlock();
205}
206}
207}
208
209if (millis() - lastClock > 1000) {
210lastClock = millis();
211if (getLocalTime(&timeinfo)) {
212char t_b[10], p_b[5], d_b[15];
213strftime(t_b, sizeof(t_b), "%I:%M", &timeinfo);
214strftime(p_b, sizeof(p_b), "%p", &timeinfo);
215strftime(d_b, sizeof(d_b), "%d/%m/%Y", &timeinfo);
216lvgl_port_lock(-1);
217lv_label_set_text(ui_LabelTime12Hr, t_b);
218lv_label_set_text(ui_LabelTimeAMPM, p_b);
219lv_label_set_text(ui_LabelDate, d_b);
220lvgl_port_unlock();
221}
222}
223delay(2);
224}

/*
* Project Name: Sentinel
* Designed For: ESP32 S3 BOX 3
*
*
* License: GPL3+
* This project is licensed under the GNU General Public License v3.0 or later.
* You are free to use, modify, and distribute this software under the terms
* of the GPL, as long as you preserve the original license and credit the original
* author. For more details, see <https://www.gnu.org/licenses/gpl-3.0.en.html>.
*
* Copyright (C) 2026 Ameya Angadi
*
* Code Created And Maintained By: Ameya Angadi
* Last Modified On: March 30, 2026
* Version: 1.0.0
*
*/

#include <Arduino.h>
#include <WiFi.h>
#include <WebServer.h>
#include <time.h>
#include <Preferences.h>
#include <esp_display_panel.hpp>
#include <lvgl.h>
#include <ui.h>
#include "lvgl_v8_port.h"

using namespace esp_panel::drivers;
using namespace esp_panel::board;

// --- CONFIGURATION ---
const char* ssid = "";
const char* password = "";
#define RXD1 40
#define TXD1 41

WebServer server(80);
Preferences prefs;
Board *board = nullptr;

// Global Data
float g_temp = 0, g_hum = 0, g_pres = 0;
float g_x = 0, g_y = 0, g_z = 0, g_vibe = 0;
String g_status = "WAITING";
String g_last_maint = "01/01/2026";
String g_next_maint = "01/07/2026";
int currentBrightness = 100;
unsigned long lastWifiCheck = 0;

// Web Server Background Color Logic (Vibrant Shades)
void handleRoot() {
String bg = "#1a1a1a"; // Dark Gray (default)
if (g_status == "DANGER") bg = "#ff4b2b"; // Vibrant Safety Red
else if (g_status == "CAUTION") bg = "#ff9800"; // Vibrant Safety Orange

String html = "<html><head><style>";
html += "body { font-family: 'Segoe UI', sans-serif; background: " + bg + "; color: white; padding: 25px; margin: 0; transition: background 0.4s; }";
html += ".card { background: rgba(0,0,0,0.75); padding: 30px; border-radius: 20px; border: 1px solid rgba(255,255,255,0.2); max-width: 450px; margin: auto; box-shadow: 0 10px 30px rgba(0,0,0,0.5); }";
html += "h2 { margin: 0; text-transform: uppercase; letter-spacing: 2px; text-shadow: 2px 2px 4px rgba(0,0,0,0.5); }";
html += ".metric { margin: 18px 0; border-bottom: 1px solid rgba(255,255,255,0.1); padding-bottom: 10px; }";
html += ".val { font-weight: bold; font-size: 1.6em; color: white; }";
html += ".label { color: #bbb; display: block; font-size: 0.85em; text-transform: uppercase; margin-bottom: 5px; }";
html += "</style></head><body><div class='card'>";
html += "<h2>SYSTEM " + g_status + "</h2><br>";

html += "<div class='metric'><span class='label'>Vibration Intensity</span><span class='val'>" + String(g_vibe) + " G</span></div>";
html += "<div class='metric'><span class='label'>Temperature</span><span class='val'>" + String(g_temp) + " C</span></div>";
html += "<div>" + String(g_hum) + "% Humidity | " + String(g_pres) + " hPa</div><br>";
html += "<div style='font-size: 0.8em; color: #aaa;'>Service: " + g_last_maint + " | Due: " + g_next_maint + "</div>";
html += "</div></body></html>";
server.send(200, "text/html", html);
}

// --- EVENT HANDLERS ---

void onBrightnessChange(lv_event_t * e) {
lv_obj_t * slider = lv_event_get_target(e);
int val = lv_slider_get_value(slider);
if (val < 10) val = 10;
currentBrightness = val;
board->getBacklight()->setBrightness(currentBrightness);
}

void updateSettingsScreenUI() {
if (millis() - lastWifiCheck > 2000) {
lastWifiCheck = millis();
String ssidStr = WiFi.SSID();
if(ssidStr.isEmpty()) ssidStr = "Searching...";
lv_label_set_text(ui_LabelWifiSSID, ("SSID: " + ssidStr).c_str());

if (WiFi.status() == WL_CONNECTED) {
lv_label_set_text(ui_LabelWifiStatus, "Status: Connected");
lv_obj_set_style_text_color(ui_LabelWifiStatus, lv_color_hex(0x00FF00), 0);
} else {
lv_label_set_text(ui_LabelWifiStatus, "Status: Disconnected");
lv_obj_set_style_text_color(ui_LabelWifiStatus, lv_color_hex(0xFF0000), 0);
}
}
}

void onMaintBtnClicked(lv_event_t * e) {
struct tm info;
if (getLocalTime(&info)) {
char buf[15];
strftime(buf, sizeof(buf), "%d/%m/%Y", &info);
g_last_maint = String(buf);
info.tm_mon += 6;
mktime(&info);
strftime(buf, sizeof(buf), "%d/%m/%Y", &info);
g_next_maint = String(buf);

prefs.begin("maint", false);
prefs.putString("last", g_last_maint);
prefs.putString("next", g_next_maint);
prefs.end();

lv_label_set_text(ui_LabelLastMaintainaceDate, g_last_maint.c_str());
lv_label_set_text(ui_LabelNextMaintDate, g_next_maint.c_str());
}
}

void setup() {
Serial.begin(115200);
Serial1.begin(115200, SERIAL_8N1, RXD1, TXD1);
Serial1.setTimeout(50);

board = new Board();
board->init();
assert(board->begin());
lvgl_port_init(board->getLCD(), board->getTouch());

lvgl_port_lock(-1);
ui_init();

if(ui_ButtonUpdateMaint) lv_obj_add_event_cb(ui_ButtonUpdateMaint, onMaintBtnClicked, LV_EVENT_CLICKED, NULL);

if (ui_SliderBrightness) {
lv_slider_set_range(ui_SliderBrightness, 10, 100);
lv_slider_set_value(ui_SliderBrightness, 100, LV_ANIM_OFF);
lv_obj_add_event_cb(ui_SliderBrightness, onBrightnessChange, LV_EVENT_VALUE_CHANGED, NULL);
}

prefs.begin("maint", true);
g_last_maint = prefs.getString("last", "01/01/2026");
g_next_maint = prefs.getString("next", "01/07/2026");
prefs.end();

lv_label_set_text(ui_LabelLastMaintainaceDate, g_last_maint.c_str());
lv_label_set_text(ui_LabelNextMaintDate, g_next_maint.c_str());
lvgl_port_unlock();

WiFi.begin(ssid, password);
server.on("/", handleRoot);
server.begin();
configTime(19800, 0, "pool.ntp.org");
}

void loop() {
server.handleClient();
static unsigned long lastClock = 0;
struct tm timeinfo;

if (lv_scr_act() == ui_SettingScreen) {
lvgl_port_lock(-1);
updateSettingsScreenUI();
lvgl_port_unlock();
}

if (Serial1.available() > 0) {
String raw = Serial1.readStringUntil('\n');
if (raw.startsWith("$[")) {
String data = raw.substring(raw.indexOf("$[") + 2, raw.indexOf("]"));
float v[7]; int count = 0;
char* ptr = strtok((char*)data.c_str(), ",");
while (ptr != NULL && count < 7) { v[count++] = atof(ptr); ptr = strtok(NULL, ","); }

if (count == 7) {
g_temp = v[0]; g_hum = v[1]; g_pres = v[2];
g_x = v[3]; g_y = v[4]; g_z = v[5]; g_vibe = v[6];

lvgl_port_lock(-1);
uint32_t s_color = 0x00FF00;
if (g_temp > 55.0 || g_vibe > 0.70) { g_status = "DANGER"; s_color = 0xFF0000; }
else if (g_temp > 42.0 || g_vibe > 0.15) { g_status = "CAUTION"; s_color = 0xFFA500; }
else { g_status = "HEALTHY"; s_color = 0x00FF00; }

lv_label_set_text(ui_LabelHealthStatus, g_status.c_str());
lv_obj_set_style_text_color(ui_LabelHealthStatus, lv_color_hex(s_color), 0);

char b[16];
snprintf(b, sizeof(b), "%.1f C", g_temp);
lv_label_set_text(ui_LabelTemp, b); lv_label_set_text(ui_LabelTempES, b);

snprintf(b, sizeof(b), "%.0f %%", g_hum);
lv_label_set_text(ui_LabelHum, b); lv_label_set_text(ui_LabelHumES, b);

snprintf(b, sizeof(b), "%.1f hPa", g_pres); lv_label_set_text(ui_LabelBMPressure, b);
snprintf(b, sizeof(b), "X: %.2f G", g_x); lv_label_set_text(ui_LabelXaxis, b);
snprintf(b, sizeof(b), "Y: %.2f G", g_y); lv_label_set_text(ui_LabelYaxis, b);
snprintf(b, sizeof(b), "Z: %.2f G", g_z); lv_label_set_text(ui_LabelZaxis, b);
snprintf(b, sizeof(b), "%.2f G", g_vibe); lv_label_set_text(ui_LabelCombinedMPU, b);
lvgl_port_unlock();
}
}
}

if (millis() - lastClock > 1000) {
lastClock = millis();
if (getLocalTime(&timeinfo)) {
char t_b[10], p_b[5], d_b[15];
strftime(t_b, sizeof(t_b), "%I:%M", &timeinfo);
strftime(p_b, sizeof(p_b), "%p", &timeinfo);
strftime(d_b, sizeof(d_b), "%d/%m/%Y", &timeinfo);
lvgl_port_lock(-1);
lv_label_set_text(ui_LabelTime12Hr, t_b);
lv_label_set_text(ui_LabelTimeAMPM, p_b);
lv_label_set_text(ui_LabelDate, d_b);
lvgl_port_unlock();
}
}
delay(2);
}

Pico DAQ Node

cpp

Code for the Pico DAQ Node (Check GitHub Repo)

1/*
2* Project Name: Sentinel
3* Designed For: Raspberry Pi Pico/Pico W
4*
5*
6* License: GPL3+
7* This project is licensed under the GNU General Public License v3.0 or later.
8* You are free to use, modify, and distribute this software under the terms
9* of the GPL, as long as you preserve the original license and credit the original
10* author. For more details, see <https://www.gnu.org/licenses/gpl-3.0.en.html>.
11*
12* Copyright (C) 2026 Ameya Angadi
13*
14* Code Created And Maintained By: Ameya Angadi
15* Last Modified On: March 30, 2026
16* Version: 1.0.0
17*
18*/
19
20#include <Wire.h>
21#include <DHT.h>
22#include <Adafruit_BMP280.h>
23#include <Adafruit_MPU6050.h>
24#include <Adafruit_Sensor.h>
25
26#define DHTPIN 15
27DHT dht(DHTPIN, DHT11);
28Adafruit_BMP280 bmp(&Wire);
29Adafruit_MPU6050 mpu;
30
31// Calibration Globals
32float baseMag = 0;
33float offX = 0, offY = 0, offZ = 0;
34float filtX = 0, filtY = 0, filtZ = 0;
35const float alpha = 0.8; // Filter strength (0.8 to 0.9 is best)
36
37void initSensors() {
38Wire.end(); Wire1.end();
39Wire.setSDA(4); Wire.setSCL(5); Wire.begin();
40bmp.begin(0x76);
41Wire1.setSDA(2); Wire1.setSCL(3); Wire1.begin();
42mpu.begin(0x68, &Wire1);
43dht.begin();
44}
45
46void calibrateMPU() {
47Serial.println("Calibrating... Keep Still!");
48float sumX = 0, sumY = 0, sumZ = 0, sumMag = 0;
49int samples = 100;
50
51for(int i = 0; i < samples; i++) {
52sensors_event_t a, g, temp;
53mpu.getEvent(&a, &g, &temp);
54sumX += a.acceleration.x;
55sumY += a.acceleration.y;
56sumZ += a.acceleration.z;
57sumMag += sqrt(pow(a.acceleration.x, 2) + pow(a.acceleration.y, 2) + pow(a.acceleration.z, 2));
58delay(10);
59}
60
61offX = sumX / samples;
62offY = sumY / samples;
63offZ = sumZ / samples;
64baseMag = sumMag / samples;
65Serial.printf("Baseline Set: %.2f m/s^2\n", baseMag);
66}
67
68void setup() {
69Serial.begin(115200);
70Serial1.begin(115200); // TX: GP0
71initSensors();
72calibrateMPU(); // Run Tare Calibration
73}
74
75void loop() {
76sensors_event_t a, g, temp_mpu;
77if (!mpu.getEvent(&a, &g, &temp_mpu)) { initSensors(); return; }
78
79// 1. DYNAMIC HIGH-PASS FILTER (The "Gravity Canceller")
80// We estimate gravity (Low Pass)
81filtX = (alpha * filtX) + ((1.0 - alpha) * a.acceleration.x);
82filtY = (alpha * filtY) + ((1.0 - alpha) * a.acceleration.y);
83filtZ = (alpha * filtZ) + ((1.0 - alpha) * a.acceleration.z);
84
85// We subtract gravity to get only Linear Acceleration (High Pass)
86float linX = a.acceleration.x - filtX;
87float linY = a.acceleration.y - filtY;
88float linZ = a.acceleration.z - filtZ;
89
90// 2. CALCULATE VIBRATION INTENSITY (G-Force)
91// This is the "Magnitude" of just the vibration components
92float vibeMag = sqrt(pow(linX, 2) + pow(linY, 2) + pow(linZ, 2)) / 9.81;
93
94// 3. GET ENVIRONMENTAL DATA
95float t = dht.readTemperature();
96float h = dht.readHumidity();
97float p = bmp.readPressure() / 100.0F;
98
99// --- PACKET SENDING ---
100// $[T, H, P, RelX, RelY, RelZ, RelVibe]*
101Serial1.print("$[");
102Serial1.print(t, 1); Serial1.print(",");
103Serial1.print(h, 0); Serial1.print(",");
104Serial1.print(p, 1); Serial1.print(",");
105Serial1.print(linX, 2); Serial1.print(","); // Cleaned X
106Serial1.print(linY, 2); Serial1.print(","); // Cleaned Y
107Serial1.print(linZ, 2); Serial1.print(","); // Cleaned Z
108Serial1.print(vibeMag, 2); // Cleaned Combined G
109Serial1.println("]*");
110
111delay(100);
112}

/*
* Project Name: Sentinel
* Designed For: Raspberry Pi Pico/Pico W
*
*
* License: GPL3+
* This project is licensed under the GNU General Public License v3.0 or later.
* You are free to use, modify, and distribute this software under the terms
* of the GPL, as long as you preserve the original license and credit the original
* author. For more details, see <https://www.gnu.org/licenses/gpl-3.0.en.html>.
*
* Copyright (C) 2026 Ameya Angadi
*
* Code Created And Maintained By: Ameya Angadi
* Last Modified On: March 30, 2026
* Version: 1.0.0
*
*/

#include <Wire.h>
#include <DHT.h>
#include <Adafruit_BMP280.h>
#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>

#define DHTPIN 15
DHT dht(DHTPIN, DHT11);
Adafruit_BMP280 bmp(&Wire);
Adafruit_MPU6050 mpu;

// Calibration Globals
float baseMag = 0;
float offX = 0, offY = 0, offZ = 0;
float filtX = 0, filtY = 0, filtZ = 0;
const float alpha = 0.8; // Filter strength (0.8 to 0.9 is best)

void initSensors() {
Wire.end(); Wire1.end();
Wire.setSDA(4); Wire.setSCL(5); Wire.begin();
bmp.begin(0x76);
Wire1.setSDA(2); Wire1.setSCL(3); Wire1.begin();
mpu.begin(0x68, &Wire1);
dht.begin();
}

void calibrateMPU() {
Serial.println("Calibrating... Keep Still!");
float sumX = 0, sumY = 0, sumZ = 0, sumMag = 0;
int samples = 100;

for(int i = 0; i < samples; i++) {
sensors_event_t a, g, temp;
mpu.getEvent(&a, &g, &temp);
sumX += a.acceleration.x;
sumY += a.acceleration.y;
sumZ += a.acceleration.z;
sumMag += sqrt(pow(a.acceleration.x, 2) + pow(a.acceleration.y, 2) + pow(a.acceleration.z, 2));
delay(10);
}

offX = sumX / samples;
offY = sumY / samples;
offZ = sumZ / samples;
baseMag = sumMag / samples;
Serial.printf("Baseline Set: %.2f m/s^2\n", baseMag);
}

void setup() {
Serial.begin(115200);
Serial1.begin(115200); // TX: GP0
initSensors();
calibrateMPU(); // Run Tare Calibration
}

void loop() {
sensors_event_t a, g, temp_mpu;
if (!mpu.getEvent(&a, &g, &temp_mpu)) { initSensors(); return; }

// 1. DYNAMIC HIGH-PASS FILTER (The "Gravity Canceller")
// We estimate gravity (Low Pass)
filtX = (alpha * filtX) + ((1.0 - alpha) * a.acceleration.x);
filtY = (alpha * filtY) + ((1.0 - alpha) * a.acceleration.y);
filtZ = (alpha * filtZ) + ((1.0 - alpha) * a.acceleration.z);

// We subtract gravity to get only Linear Acceleration (High Pass)
float linX = a.acceleration.x - filtX;
float linY = a.acceleration.y - filtY;
float linZ = a.acceleration.z - filtZ;

// 2. CALCULATE VIBRATION INTENSITY (G-Force)
// This is the "Magnitude" of just the vibration components
float vibeMag = sqrt(pow(linX, 2) + pow(linY, 2) + pow(linZ, 2)) / 9.81;

// 3. GET ENVIRONMENTAL DATA
float t = dht.readTemperature();
float h = dht.readHumidity();
float p = bmp.readPressure() / 100.0F;

// --- PACKET SENDING ---
// $[T, H, P, RelX, RelY, RelZ, RelVibe]*
Serial1.print("$[");
Serial1.print(t, 1); Serial1.print(",");
Serial1.print(h, 0); Serial1.print(",");
Serial1.print(p, 1); Serial1.print(",");
Serial1.print(linX, 2); Serial1.print(","); // Cleaned X
Serial1.print(linY, 2); Serial1.print(","); // Cleaned Y
Serial1.print(linZ, 2); Serial1.print(","); // Cleaned Z
Serial1.print(vibeMag, 2); // Cleaned Combined G
Serial1.println("]*");

delay(100);
}

Local HTML File

markup

Code for the Local HTML File (Check GitHub Repo)

1<!DOCTYPE html>
2<html>
3<head>
4<title>Sentinel Remote Dashboard</title>
5<style>
6body { background: #000; color: white; text-align: center; font-family: sans-serif; }
7iframe { width: 400px; height: 415px; border: 2px solid #333; border-radius: 10px; margin-top: 50px; }
8.info { margin-top: 10px; color: #888; }
9</style>
10</head>
11<body>
12<h1>Predictive Maintenance Monitor</h1>
13<iframe id="sentinelFrame" src="http://10.247.207.62"></iframe>
14
15<script>
16setInterval(function() {
17document.getElementById('sentinelFrame').src = document.getElementById('sentinelFrame').src;
18}, 500);
19</script>
20</body>
21</html>

<!DOCTYPE html>
<html>
<head>
<title>Sentinel Remote Dashboard</title>
<style>
body { background: #000; color: white; text-align: center; font-family: sans-serif; }
iframe { width: 400px; height: 415px; border: 2px solid #333; border-radius: 10px; margin-top: 50px; }
.info { margin-top: 10px; color: #888; }
</style>
</head>
<body>
<h1>Predictive Maintenance Monitor</h1>
<iframe id="sentinelFrame" src="http://10.247.207.62"></iframe>

<script>
setInterval(function() {
document.getElementById('sentinelFrame').src = document.getElementById('sentinelFrame').src;
}, 500);
</script>
</body>
</html>

Downloadable files

Circuit_Diagram

Use this circuit diagram to assemble the circuit.

Circuit_Diagram.png

Documentation

Sentinel Github Repo

Check this repo for all code and design files.

https://github.com/ameya-angadi/Sentinel

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