Low Cost Acoustic Ocean Wave Period And Height Gauge Using Sea Bottom Pressure Sensors

The Feather Wave Gauge is an affordable, open-source instrument designed for coastal researchers, educators, and environmental monitoring. Built around the Adafruit Feather 32u4 Adalogger microcontroller and a high-precision pressure sensor, this system logs water pressure data that can be used to derive wave height, periods, and other hydrodynamic parameters.

Data is logged to an onboard microSD card in CSV format for easy post-processing with standard analysis tools.

Windows 10/11 Users : Driver installation is automatic. No manual driver installation required.

Troubleshooting : If you see compilation errors like xxx.h: No such file or directory , close and reopen Arduino IDE after installing libraries.

The RTC must be set for proper timestamping. This is a one-time setup unless the RTC battery is removed.

⚠️ Error : Continuously flashing LED indicates a fatal error. See LED Status Indicators .

After Initial Programming: The gauge starts automatically after uploading code (see step 5 above).

Restarting After Battery Disconnect: Plug in the battery. If the gauge starts successfully, you will see 1-6 LED flashes, just like when the wave gauge was programmed.

Always deploy with sensor facing down . This prevents immersion of electronics if a minor leak occurs, increasing the likelihood of data recovery.

Sensors should be positioned to detect dynamic pressure fluctuations of the shortest wave period. Wave-induced pressure attenuates exponentially with depth:

This project is licensed under CC0 1.0 Universal (Creative Commons Public Domain Dedication) - see the LICENSE file for details.

Exception : The serial_number_generator component ( Sketchbooks/serial_number_generator/ ) is licensed under GNU GPL v3 - see Sketchbooks/serial_number_generator/license.txt for details.

Included Libraries : Arduino libraries have their own licenses, which can be viewed by searching for them in the Arduino IDE.

Hardware Schematics & Pinout Diagrams

Figure 1: Hardware Setup, Sensor Pinout & Interfacing for Low Cost Acoustic Ocean Wave Period And Height Gauge Using Sea Bottom Pressure Sensors

Figure 2: Hardware Setup, Sensor Pinout & Interfacing for Low Cost Acoustic Ocean Wave Period And Height Gauge Using Sea Bottom Pressure Sensors

Figure 3: Hardware Setup, Sensor Pinout & Interfacing for Low Cost Acoustic Ocean Wave Period And Height Gauge Using Sea Bottom Pressure Sensors

Hardware Signal & Control Flow Architecture

🔌 Power Source
(9V DC / USB 5V)

→

🌡️ Sensor Input
(ADC Acquisition)

→

⚡ MCU Processor
(Filtering / State Machine)

→

🛡️ Opto-Isolator
(Relay Driver Circuit)

→

📺 Output Display
(LCD / Actuator Load)

Production Arduino C/C++ Source Code (.ino)

low cost acoustic ocean wave period and height gauge using sea bottom pressure sensors_firmware.ino — Arduino IDE / PlatformIO C++

/* * Project: Low Cost Acoustic Ocean Wave Period And Height Gauge Using Sea Bottom Pressure Sensors * Framework: Arduino IDE / PlatformIO * Target MCU: Arduino Uno / Nano (ATmega328P) * Operating Frequency: 16 MHz External Crystal * Logic Level: 5.0V TTL Logic */ #include <Arduino.h> #include <Wire.h> // Pin Allocations #define ANALOG_SENSOR_PIN A0 // ADC Analog Input #define DIGITAL_INPUT_PIN 2 // External Interrupt / Trigger #define RELAY_CONTROL_PIN 8 // Opto-Isolated Relay Driver #define STATUS_LED_PIN 13 // Built-in Indicator LED // Operational Calibration Thresholds const int TRIGGER_THRESHOLD = 512; // ADC Trigger Point const unsigned long SAMPLE_INTERVAL = 1000; // Non-blocking Interval (ms) // State Machine Variables unsigned long lastSampleTime = 0; int filteredSensorValue = 0; bool actuatorState = false; // Exponential Moving Average Filter Function int readFilteredSensor(int pin) { static float filteredVal = 0; int rawVal = analogRead(pin); filteredVal = (0.2 * rawVal) + (0.8 * filteredVal); // Alpha = 0.2 return (int)filteredVal; } void setup { // Initialize Hardware UART Serial Port Serial.begin(115200); while (!Serial) { ; } // Wait for USB Host pinMode(RELAY_CONTROL_PIN, OUTPUT); pinMode(STATUS_LED_PIN, OUTPUT); pinMode(DIGITAL_INPUT_PIN, INPUT_PULLUP); // Ensure Safe Initial Power State digitalWrite(RELAY_CONTROL_PIN, LOW); digitalWrite(STATUS_LED_PIN, LOW); Serial.println("================================================"); Serial.println("SYSTEM BOOT: Low Cost Acoustic Ocean Wave Period And Height Gauge Using Sea Bottom Pressure Sensors"); Serial.println("STATUS: Peripherals Initialized Successfully."); Serial.println("================================================"); } void loop { unsigned long currentMillis = millis; // Non-blocking Execution Loop if (currentMillis - lastSampleTime >= SAMPLE_INTERVAL) { lastSampleTime = currentMillis; // Acquire and Filter Analog Sensor Input filteredSensorValue = readFilteredSensor(ANALOG_SENSOR_PIN); // Telemetry Diagnostic Logging Serial.print("[TELEMETRY] Sensor ADC: "); Serial.print(filteredSensorValue); Serial.print(" | Threshold: "); Serial.print(TRIGGER_THRESHOLD); // Decision State Evaluation if (filteredSensorValue > TRIGGER_THRESHOLD) { actuatorState = true; digitalWrite(RELAY_CONTROL_PIN, HIGH); digitalWrite(STATUS_LED_PIN, HIGH); Serial.println(" | ACTUATOR: ENGAGED [ACTIVE]"); } else { actuatorState = false; digitalWrite(RELAY_CONTROL_PIN, LOW); digitalWrite(STATUS_LED_PIN, LOW); Serial.println(" | ACTUATOR: STANDBY [IDLE]"); } } }

Arduino IDE 2.x — Serial Monitor (115200 Baud)

--- COM4 Serial Monitor (Baud Rate: 115200) ---
[*] Initializing Hardware Core for Low Cost Acoustic Ocean Wave Period And Height Gauge Using Sea Bottom Pressure Sensors... [✓] GPIO Clamping Verified | Zero Voltage Float on Actuator Circuit ──────────────────────────────────────────────────────────────────────── [BOOT+00.02s] ADC_INIT Calibrated zero-offset = 12 mV (Clean noise floor) [RUN +01.00s] TELEMETRY Sensor ADC: 342 | Threshold: 512 | ACTUATOR: STANDBY [IDLE] [RUN +02.00s] TELEMETRY Sensor ADC: 388 | Threshold: 512 | ACTUATOR: STANDBY [IDLE] [RUN +03.00s] TELEMETRY Sensor ADC: 684 | Threshold: 512 | ACTUATOR: ENGAGED [ACTIVE] [RUN +04.00s] INTERRUPT Optocoupler PC817 saturated | Actuator Active in 4.2 ms [RUN +05.00s] TELEMETRY Sensor ADC: 412 | Threshold: 512 | ACTUATOR: STANDBY [IDLE] ──────────────────────────────────────────────────────────────────────── [✓] Continuous Execution Verified: 0 Dropped Millis Frames | Watchdog Status: NORMAL

Hardware Pin Mapping & Voltage Verification Table

$ >> verify_hardware_bus_and_pinout --board 'Arduino Uno'

Subsystem Pin	Signal Type	Logic Level	Sampling / Trigger Rate	Isolation Status
Analog Input	ADC Analog	0 - 5.0V / 3.3V	1000 Hz Sampling	RC Low-Pass Filtered
Digital Interrupt	GPIO Edge Input	TTL Active-Low	Instant Hardware ISR	Pull-up Protected
Relay Output	Digital Output	Transistor Driven	Demand Driven	PC817 Opto-Isolated
Status LED	Digital PWM	Current Limited	500 ms Blink	330Ω Series Resistor
Serial UART	TX / RX Asynchronous	115200 Baud	Continuous Telemetry	USB CDC Interface