2 layers150 × 110 mm Lab, the printed circuit board in 3D

Lab

Yashwanth786/Centralized_Power_Distribution_System

Size: 150 × 110 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 48
Nets: 59
Pads: 164
Tracks, vias: 221, 0
Pours: 1
Routed: Yes
KiCad: KiCad 9.0 (file 20241229)
Created: 11 May 2026
Updated: 11 May 2026

Overview

Lab is an open-source printed circuit board by Yashwanth786, from the Yashwanth786/Centralized_Power_Distribution_System repository on GitHub. It is a 2-layer board of 150 × 110 mm with 48 parts on 59 nets, routed with 221 tracks and 0 vias.

It is built around the HLK-PM01, MT3608 and TP4056-42-ESOP8, with the ULN2003A, XIAO ESP32C3 and SS34 among its other parts. Its parts include 10 resistors, 8 connectors, 5 capacitors, 5 diodes and 5 switches. It belongs with the ESP32 and RISC-V boards of this library.

Main components

README

README.md

Centralized Power Distribution System

IIT Hyderabad — Electrical Engineering Laboratory

An IoT-based smart power management system for EE lab workbenches. Students request table power through a web portal by entering their roll number; lab staff monitor and control all 10 tables in real time from a central dashboard — powered by ESP32-C3 microcontrollers, Firebase Realtime Database, and automatic 18650 Li-Ion battery backup.

System Overview

[blocked] [blocked] [blocked]

Introduction & Overview
Features
System Architecture
How It Works
Hardware Design
Software Design & Frameworks
Repository Structure
Setup & Workflow
How to Run
Portal Walkthrough — Screenshots
Demo Video
Applications
Challenges Faced
Future Improvements
Team

1. Introduction & Overview

University EE labs share 10 workbenches between many student groups. Today, a lab staff member must physically walk to each table to switch power on or off, and there is no record of who used which table, when, or for how long. Power is sometimes left ON after students leave, equipment runs unattended, and there is no centralized emergency cut-off.

The Centralized Power Distribution System (CPDS) eliminates this entirely. A custom PCB at each table drives three relay-controlled socket outlets under the control of a cloud-connected Seeed Studio XIAO ESP32-C3. A React + Firebase web portal provides two portals in one URL — a Student Portal where students type their roll number and choose an available table, and a Staff Dashboard where one instructor sees all 10 tables live and can cut any session in one click.

Communication flows through Firebase Realtime Database — the portal writes isOn: true to a table's path, the ESP32 there reads it within 2 seconds and closes the relays, and the sockets go live. All events are logged with timestamps. A built-in 18650 Li-Ion battery automatically takes over if mains power is lost, and a physical emergency button on each table cuts power instantly without needing a network round-trip.

2. Features

Feature	Description
Manual Roll Number Entry	Students type their roll number in the portal — no QR scan, no app install, works on any browser
Live Table Availability	Student portal dropdown shows only currently available (unoccupied) tables in real time
3-Hour Session Timer	Each table allocation runs for 3 hours; staff dashboard shows live countdown per table
Staff Dashboard	Live grid of all 10 tables: status badge, student roll, session start time, countdown, power source, and action button
Firebase Real-Time Sync	Portal ↔ ESP32 changes propagate in under 2 seconds via Firebase `onValue` listeners
Mains / Battery Auto-Failover	ADC on GPIO D0 monitors mains via voltage divider; AO3401A P-MOSFET switches to 18650 + MT3608 boost when mains drops
Physical Emergency Button	NO push button on each table — immediately cuts all 3 relays and writes to Firebase without waiting for a network response
Bi-Color LED Indicator	Green = mains present & running; Red = battery mode / error / boot
10-Second Heartbeat	Each ESP32 writes `lastSeen` every 10 s; dashboard shows 🔴 Offline if heartbeat stops
Activity Log Panel	Every session start, end, expiry, emergency, and power event is logged to Firebase with a human-readable timestamp
All-Off Emergency Button	Staff button with confirmation modal cuts power to all 10 tables simultaneously
Session Auto-Expiry	Dashboard `Countdown` component auto-calls `deallocateTable()` when a 3-hour session reaches zero
Recent Allocations Table	Student roll-entry page shows the last 5 active allocations live — helps students see if their table is already taken

3. System Architecture

text

┌──────────────────────────────────────────────────────────────────────┐
│                          Firebase Cloud                              │
│                                                                      │
│   Realtime Database                    Firebase Hosting              │
│   ────────────────                     ────────────────              │
│   tables/T-XX/isOn          ◄──────    React Web Portal             │
│   tables/T-XX/studentRoll              ├── Student Portal            │
│   tables/T-XX/starttimeLabel  ──────►  │   Roll number entry         │
│   tables/T-XX/sessionEnd               │   Table selection           │
│   power/T-XX/source         ◄──────    │   Confirmation screen       │
│   power/T-XX/lastSeen                  └── Staff Dashboard           │
│   logs/{id}                                All 10 tables live        │
│   logCount                                 End Session / All Off     │
└──────────────────────┬───────────────────────────────────────────────┘
                       │  Wi-Fi  IEEE 802.11 b/g/n
         ┌─────────────┼──────────────┐
         │             │              │
   ┌─────▼──────┐ ┌────▼───────┐ ┌──▼──────────┐
   │  Table T-01│ │ Table T-02 │ │  Table T-10  │
   │ XIAO ESP32 │ │ XIAO ESP32 │ │  XIAO ESP32  │
   │ Custom PCB │ │ Custom PCB │ │  Custom PCB  │
   │ ULN2003APG │ │ ULN2003APG │ │  ULN2003APG  │
   │ 3× Relays  │ │ 3× Relays  │ │  3× Relays   │
   │ HLK-PM01   │ │ HLK-PM01   │ │  HLK-PM01    │

Data flow summary:

Student submits roll number → allocateTable(id, roll) → Firebase tables/T-XX/isOn = true
ESP32 polls Firebase every 2 s → reads isOn = true → setRelays(true) → sockets live
ESP32 writes power/T-XX/lastSeen every 10 s → dashboard flags Offline if missed
Staff clicks End Session → deallocateTable(id) → Firebase isOn = false → ESP32 reads → relays open

4. How It Works

Student Flow

text

Student opens web portal on any browser
              │
              ▼
Home Page  →  clicks "Student Portal" card
              │
              ▼
Roll Number Entry page (StudentScanPage):
  - Text input: type roll number e.g. "EE22BTECH11001"  →  press Next / Enter
  - Recent Allocations table shows last 5 active sessions live from Firebase
              │
              ▼
Table Selection page (StudentSelectPage):
  - Dropdown populated in real time with ONLY unoccupied tables
  - Occupied tables are excluded automatically
  - If all tables are full → yellow warning banner appears
  - Student selects table  →  "Allocate Table"
              │
              ▼
allocateTable("T-03", "EE22BTECH11001") writes to Firebase:
     tables/T-03/isOn            = true
     tables/T-03/studentRoll     = "EE22BTECH11001"
     tables/T-03/starttimeLabel  = "07/05/2026, 03:45:12 pm"
     tables/T-03/sessionEnd      = <epoch ms + 3 hours>
     tables/T-03/sessionEndLabel = "07/05/2026, 06:45:12 pm"

Staff Flow

text

Staff opens portal  →  "Technical Staff Portal"  →  Password entry
              │
              ▼
StaffLoginPage:
  - Password compared against hardcoded STAFF_PASSWORD
  - Correct  →  sessionStorage.setItem("staffAuth","true")  →  navigate to dashboard
  - Wrong    →  inline error message, password cleared
              │
              ▼
StaffDashboardPage (auth guard: redirects if staffAuth not set):
  - Three Firebase listeners started on mount:
      subscribeToTables  →  setTables state
      subscribeToPower   →  setPower  state
      subscribeToLogs    →  setLogs   state
  - Cleanup: all three unsubscribed on unmount
              │
              ▼
Dashboard header shows live stats chips: "3 Occupied  |  6 Available  |  1 Offline"

Dashboard table row per T-01…T-10:
  [Table ID] [Status badge] [Student Roll] [Start Time] [Countdown] [Power badge] [Action]
              │
              ▼
Staff clicks "⛔ End Session" on T-03:

Emergency Button (Hardware)

text

Student presses NO push button on table edge (GPIO D1, INPUT_PULLUP)
              │
              ▼
ESP32 loop: digitalRead(PIN_EMERG_BTN) = LOW
50 ms debounce elapsed, btnWasPressed was false
              │
              ▼
emergTripped = true
setRelays(false) IMMEDIATELY — no Firebase wait
D4, D3, D2 → LOW  →  relay contacts open  →  sockets DEAD
              │
              ▼
Firebase writes (best-effort):
  firebaseDeallocate("emergency_button")  →  tables/T-XX/isOn = false
  firebaseAddLog("Emergency button pressed — relays OFF", "emergency")
Red LED ON
              │
              ▼
Button released: btnWasPressed=false, emergTripped=false (auto-reset latch)
Table ready for next student

Mains Failure & Battery Failover

text

Mains power drops  →  HLK-PM01 output falls
              │
              ▼
ADC on GPIO D0 reads voltage divider:  analogRead(PIN_MAINS_ADC) < 500
mains (bool) becomes false, lastMailsState was true → change detected
              │
              ▼
updateLED(false): Green OFF, Red ON
firebaseSetPower("battery"):
  power/T-XX/source   = "battery"
  power/T-XX/lastSeen = <readable time>
              │
              ▼
If relays were ON when mains dropped:
  setRelays(false)
  firebaseDeallocate("mains_lost")
  firebaseAddLog("Mains power lost — relays turned OFF", "power")
              │
              ▼
AO3401A P-MOSFET hardware path (automatic, no firmware needed):
  HLK-PM01 rail drops  →  MOSFET gate control switches
  18650 Li-Ion  →  MT3608 boost converter  →  5V rail maintained
  ESP32 and relays stay powered
              │

5. Hardware Design

PCB Overview

Custom 2-layer PCB designed in KiCad 9. One board per lab table — 10 boards total.

PCB 3D Render

Parameter	Value
Design Tool	KiCad 9.x
Layers	2 — F.Cu (signal + power) / B.Cu (High Voltage AC Power)
Min trace width	0.3 mm signal / 1.5 mm mains
Mains isolation	3 mm creepage gap + PCB slot (Edge.Cuts)
Surface finish	HASL
Board thickness	1.6 mm
Copper weight	1 oz (35 µm)

Schematic

PCB Layout

PCB Front

Pin Map — XIAO ESP32-C3

Label	GPIO	Direction	Function
D0	2	INPUT (ADC 12-bit)	Voltage divider output — mains sense, threshold 500
D1	3	INPUT (INPUT_PULLUP)	Emergency button — NO contact, active LOW
D2	4	OUTPUT	ULN2003 I3 → Relay 3 — HIGH = relay energised = socket ON
D3	5	OUTPUT	ULN2003 I2 → Relay 2
D4	6	OUTPUT	ULN2003 I1 → Relay 1
D5	7	OUTPUT	Green LED — HIGH = mains present, no error
D10	10	OUTPUT	Red LED — HIGH = battery mode / error / boot

Power Architecture

text

230V AC Mains
     │
 [Varistor MOV]   ← surge protection
     │
 [HLK-PM01]       ← isolated SMPS, 230VAC → 5V DC
     │
     ├──────────── 5V Rail ─────────────────────────────────────┐
     │                                                          │
     │         [TP4056 charger] ←─── charges 18650 from 5V     │
     │                │                                         │
     │           [18650 Li-Ion]                                 │
     │                │                                         │
     │           [MT3608 Boost] → 5V                            │
     │                │                                      [AO3401A P-MOSFET]
     │                └─────────────────────────────────────────┘
     │                                                          │
     └──────────────────────────── 5V Supply Rail ─────────────┘
                                         │
                              [ESP32-C3 + ULN2003 + 3× Relays]

Normal: HLK-PM01 supplies the 5V rail; AO3401A gate held high → MOSFET OFF → battery path blocked
Mains failure: HLK-PM01 drops; AO3401A switches → MT3608 boosts 18650 → 5V rail sustained
Charging: TP4056 charges 18650 from the 5V mains rail while mains is present
Protection: SS34 Schottky diodes on all relay flyback paths; Varistor on AC input for surge events

Bill of Materials (BOM)

#	Component	Description	MPN	Price (Rs.)	Qty
1	Seeed Studio XIAO ESP32-C3	Wi-Fi microcontroller, USB-C, castellated	Generic	600	1
2	5V 1-Channel Relay Module	SRD-05VDC-SL-C coil, 10A contacts	SRD-05VDC-SL-C	33	3
3	ULN2003APG (Toshiba)	50V / 500mA 7-ch Darlington array — relay driver	ULN2003APG	19	1
4	Momentary Push Switch	NO contact, active-low emergency button	TSD001B07018A	20	1
5	Hi-Link HLK-PM01	230VAC → 5V / 3W isolated SMPS	HLK-PM01	200	1
6	18650 Li-Ion Battery	3.7V, 2500mAh backup cell	INR18650-25P	81	1
7	18650 Battery Holder	SMD/SMT single cell	1042P	33	1
8	TP4056 Charging Module	Adjustable 1A Li-Ion charger	TP4056	14	1
9	MT3608 Boost Converter	2A max DC-DC step-up module	MT3608	36	1
10	Bi-Color LED	5mm Red/Green dual indicator	XL-A524SURSYGW	3	1
11	6-Pin DPDT Self-Lock Switch	Latching power switch	—	6	1
12	AO3401A MOSFET	P-channel SOT-23, mains/battery path switch	AO3401A	4	1
13	3-Pin Screw Terminal	3.5mm pitch — mains & load connections	XY302V-3.5-3P	12	4
14	SS34 Schottky Diode	3A / 40V — relay flyback + path blocking	—	7	4
15	22µH Inductor SMD	MT3608 boost converter inductor	ASPI-0630LR-220M-T15	70	1
16	Varistor D15.5mm P7.5mm	MOV surge protection on AC input	561KD10J	14	1
17	PCB	Total PCB manufacturing cost	—	2936	1

Total cost = Rs. 4211 /- per Table.

Component Footprints

Component	KiCad Footprint	Library
XIAO ESP32-C3	`SeeedStudio_XIAO_ESP32C3`	Custom (castellated pads)
Relay Module	`Relay_THT:HF41F`	Standard
ULN2003APG	`Package_DIP:DIP-16_W7.62mm`	Standard
Momentary Push Switch	`Button_Switch_THT:SW_PUSH_6mm`	Standard
HLK-PM01	`Converter_ACDC:HLK-PM01`	Standard
18650 Battery Holder	`BatteryHolder_THT:BatteryHolder_Keystone_1042P`	Standard
TP4056 Module	`Module_TP4056`	Custom
MT3608 Boost Module	`Module_MT3608`	Custom
AO3401A MOSFET	`mosfet.pretty:SOT23-3`	Custom — included in `kicad/mosfet.pretty/`
Bi-Color LED	`LED_THT:LED_D5.0mm_2pin`	Standard
3-Pin Screw Terminal	`TerminalBlock_Phoenix:MKDS_3-3.5`	Standard
100µF Cap DIP	`Capacitor_THT:CP_Radial_D8.0mm_P3.50mm`	Standard
22µF Cap DIP	`Capacitor_THT:CP_Radial_D6.3mm_P2.50mm`	Standard
SS34 Schottky Diode	`Diode_THT:D_DO-201AD`	Standard
22µH Inductor SMD	`Inductor_SMD:L_Bourns_SRR1260`	Standard
All THT Resistors	`Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm`	Standard
Varistor	`Varistor_THT:RV_D15.5mm_P7.5mm`	Standard

Note: The mosfet.pretty/ folder is included in kicad/ as a relative-path library. The project will open without missing footprint errors on any machine as long as the folder structure is kept intact.

6. Software Design & Frameworks

Tech Stack

Layer	Technology	Details
Frontend	React 18.2	`create-react-app` scaffold
Routing	React Router DOM v6.21	`BrowserRouter` + `Routes` + `Route`
Database	Firebase Realtime Database v10.7	Real-time `onValue` listeners + `set` / `update` writes
Auth	Session-based (hardcoded password)	`sessionStorage.setItem("staffAuth","true")`
Hosting	Firebase Hosting	Deployed via `firebase deploy`
Firmware	Arduino / C++ on ESP32-C3	`Firebase_ESP_Client` by Mobizt, `ArduinoJson` by Blanchon

Page Map

Route	Component	What it does
`/`	`HomePage`	Landing — two hover cards: Technical Staff Portal & Student Portal
`/student/scan`	`StudentScanPage`	Roll number text input + Enter key support + recent allocations live table
`/student/select`	`StudentSelectPage`	Live dropdown of available tables + "Allocate Table" button + loading state
`/student/confirm`	`StudentConfirmPage`	Success card — roll, table (large green), "power is ON", 5-second countdown redirect
`/staff/login`	`StaffLoginPage`	Password input with show/hide toggle — stores auth in sessionStorage
`/staff/dashboard`	`StaffDashboardPage`	Full dashboard — 3 Firebase listeners, 10-table grid, logs panel, ALL OFF modal

Firebase Database Schema

json

{
  "tables": {
    "T-01": {
      "isOn": true,
      "studentRoll": "EE22BTECH11001",
      "starttimeLabel": "07/05/2026, 03:45:12 pm",
      "sessionEnd": 1715079912000,
      "sessionEndLabel": "07/05/2026, 06:45:12 pm"
    }
  },
  "power": {
    "T-01": {
      "source": "mains",
      "lastSeen": "07/05/2026, 03:50:00 pm"
    }
  },
  "logs": {
    "1": {
      "message": "Table T-01 allocated to student EE22BTECH11001",
      "tableId": "T-01",
      "type": "session_start",
      "timestamp": "07/05/2026, 03:45:12 pm"
    }
  },
  "logCount": 1
}

Key Functions — `database.js`

Function	Description
`subscribeToTables(cb)`	`onValue` on `tables/` — returns Firebase unsubscribe fn; called in useEffect cleanup
`subscribeToPower(cb)`	`onValue` on `power/` — same pattern
`subscribeToLogs(cb, limit)`	`onValue` on `logs/` with `orderByKey + limitToLast(100)`, sorted newest-first
`allocateTable(id, roll)`	Writes `isOn=true`, roll, start time label, sessionEnd epoch + label; adds `session_start` log
`deallocateTable(id, reason)`	Writes `isOn=false`, `lastUsed`; adds `session_end` or `expire` log based on reason
`allTablesOff()`	`Promise.all` over all 10 table deallocations; adds single `staff` log
`clearLogs()`	Sets `logs` and `logCount` to null/0
`clearAllData()`	Called on `App.js` mount — resets all tables to `isOn:false` and power to `offline`
`addLog({message, tableId, type})`	Reads `logCount`, increments, writes to `logs/{n}` with human timestamp
`toReadable(ms)`	Formats epoch ms → `"DD/MM/YYYY, HH:MM:SS am/pm"` (matches ESP32 output)

ESP32 Firmware — Timing Constants

`#define`	Value	Purpose
`MAINS_THRESHOLD`	500 (ADC counts)	12-bit ADC reading below this = mains lost
`DEBOUNCE_MS`	50 ms	Emergency button software debounce window
`FIREBASE_POLL_MS`	2000 ms	Interval between Firebase `getBool` reads for `isOn`
`HEARTBEAT_INTERVAL_MS`	10000 ms	Interval between `lastSeen` + power source writes

App.js — Startup Behaviour

On every portal load, App.js calls clearAllData() in a useEffect. This resets all 10 tables to isOn: false and all power entries to source: "offline" — ensuring a clean slate each time staff open the portal.

7. Repository Structure

text

centralized-power-distribution/
│
├── README.md                              ← This file
├── PCB.pdf                                ← Hardware reference (schematic, BOM, footprints, gerbers)
├── .gitattributes
│
├── kicad/                                 ← All KiCad design files
│   ├── lab.kicad_pro                      ← Open this in KiCad 7 to load the full project
│   ├── lab.kicad_sch                      ← Complete schematic
│   ├── lab.kicad_pcb                      ← PCB layout with copper pours and component placements
│   ├── lab.kicad_prl                      ← Project-level layer/render preferences
│   ├── New_Library.kicad_sym              ← Custom schematic symbols library
│   ├── mosfet.kicad_sym                   ← AO3401A schematic symbol
│   ├── mosfet.pretty/
│   │   └── SOT23-3.kicad_mod              ← Custom AO3401A PCB footprint (SOT-23-3, 0.95mm pitch)
│   ├── sym-lib-table                      ← Symbol library path references
│   ├── fp-lib-table                       ← Footprint library path references
│   └── lab_output/                        ← Gerber files — ZIP this folder and send to manufacturer
│       ├── lab-F_Cu.gbr                   ← Front copper traces
│       ├── lab-B_Cu.gbr                   ← Back copper ground plane
│       ├── lab-F_Mask.gbr                 ← Front solder mask
│       ├── lab-B_Mask.gbr                 ← Back solder mask
│       ├── lab-F_Silkscreen.gbr           ← Front silkscreen labels
│       ├── lab-B_Silkscreen.gbr           ← Back silkscreen

8. Setup & Workflow

Prerequisites

Node.js ≥ 16 and npm
Arduino IDE 2.x
KiCad 9.x (for PCB files)
A Firebase project with Realtime Database enabled

Step 1 — Firebase Project

Go to console.firebase.google.com → Create project
Enable Realtime Database — choose Asia Southeast 1 for lowest latency from India

Set temporary development rules:

json

{ "rules": { ".read": true, ".write": true } }

Copy your Web API Key from Project Settings → General
Copy your Database URL from the Realtime Database panel
Create a Legacy Database Secret from Project Settings → Service Accounts → Database Secrets — this is needed by the ESP32

Step 2 — Web Portal

bash

cd web-portal/
npm install

File 1 — Firebase credentials

Open web-portal/src/firebase/config.js and replace the values directly:

const firebaseConfig = {
  apiKey:            "YOUR_WEB_API_KEY",
  authDomain:        "YOUR_PROJECT_ID.firebaseapp.com",
  databaseURL:       "https://YOUR_PROJECT_ID-default-rtdb.asia-southeast1.firebasedatabase.app",
  projectId:         "YOUR_PROJECT_ID",
  storageBucket:     "YOUR_PROJECT_ID.appspot.com",
  messagingSenderId: "YOUR_SENDER_ID",
  appId:             "YOUR_APP_ID"
};

File 2 — Staff password

Open web-portal/src/pages/StaffLoginPage.jsx and find line near the top:

const STAFF_PASSWORD = "your_chosen_password";

Step 3 — ESP32 Firmware

Install Arduino libraries (Tools → Manage Libraries):

Firebase ESP Client by Mobizt
ArduinoJson by Benoit Blanchon

Add XIAO board package — File → Preferences → Additional Boards Manager URLs:

text

https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json

Then install esp32 by Espressif Systems in Boards Manager.

Edit the 5 marked lines at the top of lab_controller_v3.ino:

cpp

#define WIFI_SSID         "YOUR_WIFI_SSID"        // your Wi-Fi network name
#define WIFI_PASSWORD     "YOUR_WIFI_PASSWORD"     // your Wi-Fi password
#define TABLE_ID          "T-01"                   // change per board: T-01 … T-10
#define FIREBASE_API_KEY  "YOUR_WEB_API_KEY"       // from Firebase Project Settings → General
#define DATABASE_URL      "YOUR_DATABASE_URL"      // from Firebase Realtime Database panel

Also update the legacy token:

cpp

config.signer.tokens.legacy_token = "YOUR_DATABASE_SECRET"; // from Project Settings → Service Accounts → Database Secrets

Arduino IDE board settings:

Setting	Value
Board	XIAO_ESP32C3
Upload Speed	921600
USB CDC On Boot	Enabled

Flash each of the 10 boards with a unique TABLE_ID (T-01 through T-10). After flashing, open Serial Monitor at 115200 baud — first lines should be:

text

=== IIT-H EE Lab ESP32 v3.0 ===
Table: T-01
[WiFi] Connecting to YOUR_SSID
[Firebase] Connected OK
[Boot] Ready.

9. How to Run

Web Portal — Development

bash

cd web-portal/
npm start
# Opens at http://localhost:3000

Web Portal — Production (Firebase Hosting)

bash

npm run build
npm install -g firebase-tools
firebase login
firebase init hosting
# → Public dir: build
# → Configure as SPA: Yes
# → Overwrite build/index.html: No
firebase deploy
# Live at https://your-project.web.app

ESP32 Boards

Connect XIAO ESP32-C3 via USB-C
Set the correct TABLE_ID for this board
Select the correct port in Arduino IDE
Click Upload (Ctrl+U)
Verify serial output shows correct TABLE_ID
Repeat for all 10 boards (T-01 → T-10)

Once all boards are powered and connected to Wi-Fi, the staff dashboard will show ⚡ Mains for each online table within 10 seconds (first heartbeat).

10. Portal Walkthrough — Screenshots

Home Page

The landing page displays the IIT Hyderabad logo, university name, and lab title. Two clickable cards navigate to the Staff and Student portals. Cards lift and border turns orange on hover.

Student — Roll Number Entry

Roll Number Entry

Students type their roll number (e.g. EE22BTECH11001) and press Next or hit Enter. A "Recent Allocations" table below the input shows the last 5 active sessions — roll number, table, and date — pulled live from Firebase.

Student — Table Selection

Table Selection

A dropdown lists only currently unoccupied tables in real time. The page shows how many tables are available. If all tables are occupied, a yellow warning banner appears instead of the dropdown. Student selects a table and clicks Allocate Table.

Student — Confirmation

Confirmation

A green-bordered card confirms the allocation: roll number, allotted table number displayed large in green, "please go to the table, the power is ON", and session duration (3 hours). The page automatically redirects back to home after 5 seconds.

Staff — Login

Staff Login

A centered card with a lock icon and a password field. The 👁️ button toggles password visibility. Correct password stores staffAuth in sessionStorage and navigates to the dashboard. Wrong password shows an inline red error.

Staff — Dashboard

Staff Dashboard

The full control centre. A sticky orange header shows "Technical Staff Portal", live status chips (Occupied / Available / Offline counts), a Show Logs toggle, and the red ⛔ ALL OFF emergency button.

The main table has one row per lab table (T-01 to T-10), each showing:

Table ID — bold identifier
Status badge — 🟢 Available / 🟠 Occupied (pulsing dot) / ⚫ Off
Student Roll — monospace, shown only when occupied
Start Time — human-readable session start timestamp
Time Remaining — live HH:MM:SS countdown (turns red in last 10 minutes)
Power Source — ⚡ Mains / 🔋 Battery / 🔴 Offline
⛔ End Session — red button visible only for occupied tables

The Activity Logs panel (toggled from header) shows all events with type-coded badges: SESSION START / SESSION END / EXPIRE / EMERGENCY / POWER / STAFF. A "Clear Logs" button resets the log in Firebase.

11. Demo Video

Watch the demo video here: Demo Video)

What the demo shows:

Student enters roll number → selects table → confirmation screen → sockets go live
Staff dashboard updates in real time — table flips to Occupied with live countdown
Staff ends session from dashboard → relays cut → table returns to Available
Emergency button press on table → immediate relay cutoff → dashboard updates to Off
Mains disconnected → battery failover → 🔋 Battery badge appears on dashboard

12. Applications

Domain	Use Case
University EE Labs	Controlled, authenticated, logged power access for shared workbenches — primary use case
School Electronics Labs	Staff-supervised power control preventing unsupervised student equipment use
Makerspaces	Per-member metered power access with session logging and time limits
Industrial Test Stations	Remote power management for shared test benches in manufacturing or R&D environments
Exam / Assessment Centres	Timed, per-seat power allocation with automatic expiry for practical examinations

13. Challenges Faced

#	Challenge	Category	Resolution
1	ADC mains-sense gave noisy readings — false failover triggers every few seconds	Hardware	Added 100µF + 22µF capacitors across voltage divider output to GND; 5-consecutive-reading hysteresis in firmware
2	Relay chatter during mains → battery transition (~80 ms power sag caused ESP32 brownout)	Hardware	Added 100µF bulk capacitor directly on 5V rail near ESP32 VCC pin — bridges the switchover gap
3	AO3401A gate drive: ESP32 3.3V GPIO cannot fully turn OFF a 5V P-channel MOSFET	Hardware	Added NPN transistor level-shift stage; 120kΩ pull-up to 5V rail for proper gate-high state
4	KiCad standard library had no AO3401A SOT-23-3 footprint at correct 0.95mm pin pitch	Hardware	Created `mosfet.pretty` custom footprint library — included in the repo
5	Initial PCB layout violated IPC-2221 mains creepage distance between AC and DC traces	Hardware	Redesigned layout with 3mm gap + physical PCB slot in Edge.Cuts layer
6	Firebase streaming (persistent HTTPS) connection dropped frequently on lab Wi-Fi idle timeout	Firmware	Switched to 2-second polling with `Firebase.RTDB.getBool()` — stable, latency acceptable for power control
7	Emergency button mechanical bounce caused 3–5 spurious `LOW` reads per single press	Firmware	50 ms software debounce + `btnWasPressed` latch; latch clears only on release (HIGH), not press
8	`onValue` listeners stacked on re-navigation — 3 → 6 → 9 active listeners after 3 visits to dashboard	Software	`useEffect` cleanup returns and calls all three Firebase unsubscribe functions on component unmount
9	Session countdown timer drifted 5–10 s per hour using `setInterval` decrement counter	Software	Changed to `Math.max(0, sessionEnd - Date.now())` per tick — always accurate, drift-free

14. Future Improvements

OTA Firmware Updates — Push new firmware to all 10 boards wirelessly via Firebase Functions; eliminates need to physically connect each ESP32
EEPROM-Based TABLE_ID Provisioning — Store TABLE_ID in flash memory; configure once over Serial without recompiling the firmware
Energy Metering — Add INA219 current sensor per table; log per-session energy consumption (Wh / kWh) to Firebase
Admin Analytics Dashboard — Usage heat maps, per-table uptime percentages, peak hours graphs, battery health indicators
Email / SMS Alerts — Notify staff automatically when a table goes offline, battery is low, or an emergency is triggered
RFID / ID Card Authentication — Replace manual roll number typing with RFID card tap for faster, error-free student identification
Tighter Firebase Security Rules — Rate-limit student allocations; validate roll number format server-side; restrict isOn writes to authenticated users only
Progressive Web App (PWA) — Add service worker and manifest so students can install the portal to their phone home screen with offline fallback

15. Team

Name	Role Number	Contribution
Chinthalapudi Yashwanth	EE22BTECH11016	Hardware Design & PCB Layout (KiCad)
Abburi Naga Sai Ram	EE22BTECH11201	ESP32 Firmware & Web Portal Development

Institution: Indian Institute of Technology Hyderabad
Department: Electrical Engineering
Course: Electronic System Design Project Lab
Faculty Advisor: Dr. Abhishek Kumar
Academic Year: 2025–26

Category and platform

ESP32 RISC-V

Project files

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https://pcbkit.io/boards/Yashwanth786/Centralized_Power_Distribution_System

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Source

Repository: Yashwanth786/Centralized_Power_Distribution_System
Board file: kicad/lab.kicad_pcb
Commit: 7ed4748
Licence: Not stated

Parts

Qty	Value	Footprint	References
4	Conn_01x02_Pin	Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical	J5, J6, J7, J8
4	MountingHole_2.2mm_M2_DIN965_Pad	MountingHole:MountingHole_2.2mm_M2_DIN965_Pad	2.2mm, 2.2mm, 2.2mm, 2.2mm
4	SS34	Diode_SMD:D_SMA	D2, D3, D4, D5
3	0	Resistor_SMD:R_0805_2012Metric	R11, R12, R13
3	10k	Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P5.08mm_Vertical	R2, R3, R7
3	SANYOU_SRD_Form_C	Relay_THT:Relay_SPDT_SANYOU_SRD_Series_Form_C	K1, K2, K3
2	100nF	Capacitor_THT:C_Disc_D5.0mm_W2.5mm_P5.00mm	C1, C5
2	22uF	Capacitor_THT:C_Disc_D5.0mm_W2.5mm_P5.00mm	C3, C4
2	330	Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P5.08mm_Vertical	R8, R9
1	1.2k	Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P5.08mm_Vertical	R1
1	100uF	Capacitor_THT:CP_Radial_D8.0mm_P3.50mm	C2
1	120k	Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P5.08mm_Vertical	Rf1
1	15k	Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P5.08mm_Vertical	Rg1
1	18650_Li_Ion	Battery:BatteryHolder_Keystone_1042_1x18650	BT1
1	20k	Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P5.08mm_Vertical	R6
1	22uH	Inductor_SMD:L_Abracon_ASPI-0630LR	L1
1	230V_AC	TerminalBlock_Phoenix:TerminalBlock_Phoenix_PT-1,5-3-3.5-H_1x03_P3.50mm_Horizontal	J1
1	AO3401A	mosfet:SOT23-3	Q1
1	HLK-PM01	Converter_ACDC:Converter_ACDC_Hi-Link_HLK-PMxx	PS1
1	LED_Dual_AAK	LED_THT:LED_D5.0mm-3	D1
1	MT3608	Package_TO_SOT_SMD:SOT-23-6	U4
1	Relay1	TerminalBlock_Phoenix:TerminalBlock_Phoenix_PT-1,5-3-3.5-H_1x03_P3.50mm_Horizontal	J2
1	Relay2	TerminalBlock_Phoenix:TerminalBlock_Phoenix_PT-1,5-3-3.5-H_1x03_P3.50mm_Horizontal	J3
1	Relay3	TerminalBlock_Phoenix:TerminalBlock_Phoenix_PT-1,5-3-3.5-H_1x03_P3.50mm_Horizontal	J4
1	SW_Push	Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical	SW1
1	SW_Push_DPDT	Button_Switch_THT:SW_PUSH_E-Switch_FS5700DP_DPDT	SW2
1	TP4056-42-ESOP8	Package_SO:SOIC-8-1EP_3.9x4.9mm_P1.27mm_EP2.41x3.3mm_ThermalVias	U3
1	ULN2003A	Package_DIP:DIP-16_W7.62mm	U2
1	Varistor	Varistor:RV_Disc_D15.5mm_W3.9mm_P7.5mm	RV1
1	XIAO_ESP32C3	XIAO_ESP32C3:MODULE_XIAO_ESP32C3	U1

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Questions

How big is the Lab PCB?

It measures 150 × 110 mm and has 2 copper layers, 1.6 mm thick.

What parts does the Lab use?

48 parts, built around the HLK-PM01, MT3608, TP4056-42-ESOP8 and ULN2003A. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the Lab KiCad files?

From the Yashwanth786/Centralized_Power_Distribution_System repository on GitHub, at the commit this page was made from: the board is kicad/lab.kicad_pcb and its schematic kicad/lab.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the Lab design in my own project?

Its repository states no licence, so its author keeps all rights: ask Yashwanth786 before reusing the design.

Overview

Main components

HLK-PM01

MT3608

TP4056-42-ESOP8

ULN2003A

XIAO ESP32C3

SS34

AO3401A

README

Centralized Power Distribution System

IIT Hyderabad — Electrical Engineering Laboratory

Table of Contents

1. Introduction & Overview

2. Features

3. System Architecture

4. How It Works

Student Flow

Staff Flow

Emergency Button (Hardware)

Mains Failure & Battery Failover

5. Hardware Design

PCB Overview

Schematic

PCB Layout

Pin Map — XIAO ESP32-C3

Power Architecture

Bill of Materials (BOM)

Component Footprints

6. Software Design & Frameworks

Tech Stack

Page Map

Firebase Database Schema

Key Functions — database.js

ESP32 Firmware — Timing Constants

App.js — Startup Behaviour

7. Repository Structure

8. Setup & Workflow

Prerequisites

Step 1 — Firebase Project

Step 2 — Web Portal

File 1 — Firebase credentials

File 2 — Staff password

Step 3 — ESP32 Firmware

9. How to Run

Web Portal — Development

Web Portal — Production (Firebase Hosting)

ESP32 Boards

10. Portal Walkthrough — Screenshots

Home Page

Student — Roll Number Entry

Student — Table Selection

Student — Confirmation

Staff — Login

Staff — Dashboard

11. Demo Video

12. Applications

13. Challenges Faced

14. Future Improvements

15. Team

Parts

Similar boards

Questions

How big is the Lab PCB?

What parts does the Lab use?

Where can I download the Lab KiCad files?

Can I use the Lab design in my own project?

Key Functions — `database.js`