ESP32 Metal Detector using LC Oscillator

DIY metal detector uses ESP32 with LC (inductor-capacitor) oscillator circuit to detect metallic objects. Search coil (50 turns of 26AWG wire, 20cm diameter) forms the inductor in the oscillator. When metal object enters coil field, it changes oscillation frequency. ESP32 measures frequency change using internal hardware timer and triggers alarm proportional to frequency deviation. Circuit: LC oscillator built with BC547 transistor, the coil, and 100nF capacitor. Oscillator output -> GPIO4 (input capture). Baseline calibration: ESP32 measures stable frequency without metal, any deviation > threshold triggers alarm. OLED display shows signal strength bar, frequency change, sensitivity setting, battery level. Buzzer pitch and rate increase proportionally to detected metal proximity. Sensitivity adjustment via rotary encoder. Supported metal types: ferrous (iron, steel - strong response), non-ferrous (copper, aluminum, gold - weaker response). Libraries: ESP32 hardware timer, U8g2 OLED.

Detailed Project Description

ESP32 Metal Detector using LC Oscillator focuses on a specific hardware interface or peripheral and shows exactly how to wire it, drive it from firmware and verify it is working.

How It Works
1. The peripheral is connected to the controller using the required bus (SPI/I2C/UART/I2S/CAN/RS-485/PWM/ADC).
2. The driver library is initialised and the peripheral configured.
3. Firmware exchanges data with the peripheral and processes it (measure, decode, render, play).
4. Results are verified on a display, serial monitor or the receiving device.

Key Components and Their Role
- ESP32: dual-core Wi-Fi + Bluetooth microcontroller that runs the firmware, reads the sensors and hosts the network connection.
- OLED display (SSD1306): 128x64 I2C display used to show live readings and status.
- Buzzer: audible alert output.
- Li-ion battery + charger (TP4056): portable power with charge management.

Implementation Steps
1. Collect the components and study each module's datasheet (pin-out, voltage, interface).
2. Wire the circuit on a breadboard following the pin mapping; power sensors from the correct rail (3.3 V / 5 V).
3. Install Arduino IDE, U8g2 Library, ESP32 Timer Library and the required libraries; flash a minimal test sketch for each module separately.
4. Write the main firmware: read sensors → process → drive outputs / send data.
5. Configure network or cloud credentials and test communication end-to-end.
6. Calibrate thresholds, add error handling (reconnect, sensor time-out) and run a long-duration test.
7. Finalise on a PCB / enclosure and document wiring, code and results.

Key Features
- Correct wiring and bus configuration
- Driver setup
- Data processing
- Verification on real hardware

Expected Output
On completion the student will have a working peripheral that is measured/driven exactly as intended.

Deliverables
- Complete source code with comments
- Circuit diagram and pin mapping
- Project report with screenshots and results
- Demonstration-ready build