Step 1: On the device Home screen, navigate to WiFi Portal and press SELECT to confirm.

Step 2: The OLED display will show the WiFi network name and IP address. Connect your phone or computer to the displayed WiFi network.

Step 3: Open any web browser and go to 192.168.4.1

Tip: The portal will auto-shutdown after 5 minutes of inactivity to conserve battery.

Use the WiFi portal upload flow at 192.168.4.1. The device validates each upload and streams data to SD storage safely.

Files are sorted newest-first in firmware and the list is capped at 200 files for RAM safety.

The system accepts only .txt files and rejects empty or oversized uploads.

Limits: 2 MB max upload size and 64 KB max web editor file size.

The Editor tab is your main workspace: type or paste text, use formatting tools, and preview wrapped output live on the OLED simulator.

The editor shows a live character and line counter. Click Save to push content to the device backend endpoint, or Close to reset the editor session.

Use Ctrl+S (or Cmd+S) as a keyboard shortcut to save.

Limit: Web editing supports files up to 64 KB. For larger files, download, edit locally, and re-upload.

UP Button (GPIO13): Navigate up through menus. In reading mode, short press scrolls up by one page; hold for continuous line-by-line scrolling.

DOWN Button (GPIO0): Navigate down through menus. In reading mode, short press scrolls down by one page; hold for continuous scrolling. Do not hold during power-on (boot pin).

SELECT Button (GPIO12): Context-aware action. In menus, it enters the selected item. In reading mode, it acts as Back.

Flow: Home → WiFi Portal / Files / Settings. Files → Select file → Reading mode. SELECT always returns to the previous screen.

Battery: 3.7V 1100mAh Li-ion cell with TP4056 USB charging. Red LED = charging, Blue/Green LED = fully charged.

Auto Sleep: After 5 minutes of inactivity, the device enters light sleep. Display turns off, CPU power draw is minimised.

Wake Up: Press any button (UP, DOWN, or SELECT) to instantly resume from where you left off.

WiFi Power: WiFi and Bluetooth radios are fully disabled during reading. They activate only when entering WiFi Portal from the Home menu.

Magnetic Switch: The magnetic reed switch provides hardware power cutoff — zero standby drain, ideal for long-term storage.

Main Entry: D.E.V_Darshan_Sketch.ino controls setup and loop flow.

Core Modules: config (pins/settings), display (OLED rendering), sd_reader (line reader + bookmarks), buttons (debounce/press types), wifi_portal (AP + web server), and portal.h (embedded UI).

Design Decisions: line-by-line buffering keeps memory usage stable, bookmarks persist using ESP32 Preferences (NVS), and SD_MMC 1-bit mode frees critical GPIOs for safer boot.

State Flow: BOOT_INIT → HOME → FILE/SETTINGS/WIFI_PORTAL → READING.

Toolchain: Arduino IDE 2.x or PlatformIO with ESP32 board package (2.0.x+).

Board: AI Thinker ESP32-CAM, upload speed 115200, QIO flash mode, 80MHz flash frequency, default 4MB with SPIFFS partition.

Libraries: U8g2 plus built-in ESP32 libraries (WebServer, WiFi, SD_MMC, Preferences, FS).

Important: after final assembly, GPIO1/GPIO3 are reused for OLED I2C, so serial debugging is limited and OLED status output is preferred.