Cheating Calculator (ESP32-S3)

⚠️ Disclaimer This project is built strictly for educational and experimental purposes. It demonstrates embedded systems, low-power design, and hardware hacking concepts. Do not misuse this project in real exams or unethical scenarios.

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📦 Project Overview

This project converts a normal scientific calculator into a smart ESP32-based device using an ESP32-S3 Super Mini. It features a hidden OLED display, magnetic power control, Wi-Fi file upload, and low-power operation.

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🧰 Components Used

• ESP32-S3 Super Mini
• 128×32 OLED Display (I²C)
• Reed Switch (magnetic power control)
• 450mAh Li-ion Battery
• Scientific Calculator (donor body & buttons)
• Wires, black electrical tape
• USB-C cable

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🔌 Pinout Used

OLED Display (I²C)

• GPIO 5 → SDA
• GPIO 6 → SCL

Calculator Buttons

• GPIO 8
• GPIO 9
• GPIO 12

Only 3 GPIOs are used to interface all buttons.

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🛠️ Step-by-Step Build Process

1️⃣ Opening the Calculator

Carefully open the calculator casing without damaging the front keypad or PCB.

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2️⃣ Identifying Button Pads

Use the image below to identify which calculator button pads are required.

(Shows the calculator buttons used in this project)

These pads will be connected to ESP32 GPIOs.

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3️⃣ Tapping the Button Traces

Instead of individual buttons, traces are tapped directly to reduce wiring.

(Shows where wires are soldered onto PCB traces)

Carefully solder thin wires to these traces.

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4️⃣ Connecting the ESP32-S3

• Connect the button wires to GPIO 8, 9, and 12
• Connect the OLED display to GPIO 5 (SDA) and GPIO 6 (SCL)

Ensure proper grounding and short wire lengths.

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5️⃣ Power & Battery Setup

• Battery positive → ESP32 power terminal
• Battery negative → Reed switch → ESP32 GND

This allows the device to turn ON only when a magnet is nearby.

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6️⃣ Fitting Components Inside the Case

• Remove excess plastic from inside the calculator shell
• Carefully place the ESP32, OLED, and battery
• Use black electrical tape to hide the OLED from the front

Mark the visible text area beforehand.

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7️⃣ Closing the Back Cover

The back cover will not fit immediately.

✔️ Apply patience and small adjustments ✔️ Avoid pressing directly on the OLED

Once adjusted, the cover fits securely.

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📡 File Upload Process (Wi-Fi)

1. Power the calculator using the USB-C port
2. Go to the Wi-Fi Upload option on the device
3. Connect your phone/PC to the calculator’s Wi-Fi
4. Enter the password shown on the OLED
5. Open a browser and visit the IP address displayed

(Future upgrade: clickable text link on OLED)

Uploading Files

• Only .txt files are supported
• Click Upload, select file, and upload
• File appears instantly on the calculator

Deleting Files

• Reconnect to the calculator Wi-Fi
• Open the same web interface
• Delete files directly from the browser

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🔋 Charging the Battery

1. Press & hold the panic button to turn off the screen
2. Bring a magnet near the reed switch
3. Blue LED ON → Battery charging

⏱️ 30 minutes charging ≈ 3+ hours backup

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🚀 Final Notes

This project is a combination of:

• Embedded programming
• Power optimization
• Hardware reverse engineering
• Creative enclosure hacking

Feel free to modify, improve, or learn from it.

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🙌 Thanks for checking out this project

If you liked it, consider starring ⭐ the repo and following for more ESP32 projects!