Portable ESP32 Captive-Portal Wi-Fi Cloner

Tiny ESP32 app that scans nearby Wi-Fi networks on a 1.5" SPI OLED (128×128, SH1107), lets you pick one (or a custom preset), and spins up a captive-portal SoftAP with that SSID. Android/iOS/laptops will get a login prompt and see a simple “Hello” page where users can submit a name that shows on the screen.

Features

• 128×128 SH1107 OLED UI (u8g2) with smooth marquee for long SSIDs
• Non-blocking Wi-Fi scan (async) with periodic refresh
• Captive portal (AsyncWebServer + DNSServer) with Android probes handled
• Three buttons: Up / Down / OK (with debounced repeat/hold)
• Custom Wi-Fi submenu (editable list)
• Works on common ESP32-WROOM-32 dev boards

Hardware

Display module

GME128128091-SPI v3.1 (or any 1.5" SH1107 SPI OLED, 128×128)

Warning

Many of these OLED boards want VCC = 5V, not 3V3.
They often include a 3.3 V regulator and level shifting, but check your module.

Buttons

3× momentary tact switches (e.g., 6×6×8 mm; any 6×6 should work).
One leg to the ESP32 GPIO, the opposite leg to GND (we use INPUT_PULLUP).

Bill of Materials (minimal)

• ESP32-WROOM-32 dev board
• 1.5" SH1107 128×128 SPI OLED
• 3× tact switches (6×6)
• Breadboard / wires (keep SPI wires ≤10 cm to avoid noise)

Pinout

OLED (SPI) → ESP32

OLED Pin	Function	ESP32 Pin
VCC	Power	3v3
GND	Ground	GND
SCL	SPI CLK	GPIO18
SDA	SPI MOSI	GPIO23
CS	Chip Select	GPIO5
DC	Data/Command	GPIO16
RST	Reset	GPIO17

Note: SCL=SCK/CLK; SDA=MOSI (this OLED doesn’t use MISO).

Buttons → ESP32

Each button: one leg to the GPIO, the other leg to GND.

Button	Function	ESP32 Pin
Up	Input	GPIO4
Down	Input	GPIO19
OK	Input	GPIO21

Libraries / IDE

Tested with Arduino Core for ESP32 3.x.

Install (Library Manager or GitHub):

• U8g2 by olikraus
• ESPAsyncWebServer (latest dev)
• AsyncTCP (latest dev)
• (bundled) DNSServer and WiFi from ESP32 core

Configuration

• Custom SSIDs (the preset list):

 const char* CUSTOM_SSIDS[] = {
   "ESP32 Wifi", "Free WiFi", "Guest AP", "My Portal", "Cafe Hotspot"
 };

• Pins: change the #define mappings near the top if your board differs.
• Contrast / rotation: u8g2.setContrast(220) and ROTATION U8G2_R0.
• Scan cadence: RESCAN_MS (default 10s).

Known quirks / troubleshooting

• Garbage or shifted screen:
  Confirm it’s an SH1107 128×128 (not SSD1351, not SH1106).
  Keep SPI wires short (≤10 cm).
  Ensure DC/RST are not swapped.
  Many 1.5" modules require 5V VCC.

• No captive-portal prompt on Android:
  Make sure you joined the AP and mobile data is off.
  Try toggling Wi-Fi off/on.
  Paths like /generate_204 and /google/generate_204 are implemented to trigger captive helper.
  Some vendors cache—forget the AP and re-join.

• SSID contains emojis / non-ASCII:
  The OLED font is ASCII. Unsupported glyphs show as ?.
  Long names are trimmed with "...".

Build

Arduino IDE: open .ino and Upload
PlatformIO: pio run -t upload