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Feather Wave Gauge

License: CC0-1.0 Arduino

wavegaugephoto

Overview

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.

The wave gauge is particularly well-suited for:

  • Nearshore wave monitoring and coastal dynamics research
  • Storm surge and flood monitoring
  • Research deployments requiring multiple sensor arrays

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

Maintained by: NHERI RAPID

Table of Contents

Features

  • Low Cost: Economical alternative to commercial wave gauges
  • Flexible Sampling: Supports continuous and burst sampling modes
  • Autonomous Operation: Battery-powered with long deployment durations up to several months
  • Real-Time Clock: Accurate timekeeping over many months with RTC module
  • Configurable: User-adjustable sampling rates and burst parameters

Key Components

  • sketchbooks/feathergauge_code/: The primary Arduino sketch for data logging. Configure sampling parameters in user_config.h before uploading.
  • sketchbooks/rtc_setup/: Required utility to synchronize the real-time clock before use (unless using automatic programming).
  • libraries/: All necessary Arduino libraries packaged as ZIP files.
  • automatic_programming/: Tools for programming multiple wave gauges efficiently (Windows only).
  • build_info/: Hardware assembly guide, bill of materials, and 3D models for internal components.

System Requirements

Software

  • Arduino IDE (latest version recommended)
  • Windows 10/11 (for automatic driver installation) or Linux/Mac with appropriate drivers

Target Hardware

  • Microcontroller: Adafruit Feather 32u4 Adalogger
  • Pressure Sensor: SparkFun MS5803-14BA
  • Storage: MicroSD card (8GB recommended, large capacity cards may not work correctly)
  • RTC: DS3231 Real-time clock, connected to microcontroller using I2C

Getting Started

1. Software Installation

Download the Arduino IDE from arduino.cc

Configure Board Support:

  1. Open Arduino IDE and navigate to File → Preferences

  2. Add the Adafruit boards URL to "Additional Boards Manager URLs":

    https://adafruit.github.io/arduino-board-index/package_adafruit_index.json

    Detailed instructions

  3. Go to Tools → Board → Boards Manager

  4. Search for "Adafruit AVR Boards" (leave Type set to "All")

  5. Install the board package

  6. Close and reopen Arduino IDE (required for changes to take effect)

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

2. Library Setup

  1. Download this repository as a ZIP file (Code → Download ZIP)
  2. Extract to a location on your local hard drive
  3. In Arduino IDE, navigate to Sketch → Include Library → Add .ZIP Library...
  4. Navigate to the libraries/ folder in the extracted repository
  5. Add each .ZIP file one at a time:
    • Adafruit_BusIO-master.zip
    • Low-Power-1.81.zip
    • RTClib-2.1.4.zip
    • SD-master.zip
    • TimerOne-<version>.zip

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

3. Arduino IDE Configuration

  1. Connect the Feather board to your computer using a micro-USB cable
  2. In Arduino IDE, click the board selection dropdown (upper left)
  3. Click "Select other board and port..."
  4. Under Boards, search for and select "Adafruit Feather 32u4"
  5. Under Ports, select the COM port labeled with (USB)
    • If multiple USB ports appear, try each until successful upload

4. Setting the Real-Time Clock

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

Setting the Clock:

  1. Open sketchbooks/rtc_setup/rtc_setup.ino in Arduino IDE
  2. Ensure the correct board and port are selected
  3. Click Upload
    • If upload hangs on "Waiting for upload port," press the small black reset button on the board
  4. Once uploaded, open Serial Monitor (magnifying glass icon, top right)
  5. Set baud rate to 57600 baud if message appears corrupted
  6. Type the current date/time in the Serial Monitor message box using this format: 
    MMM DD YYYY HH:MM:SS
    Example: Dec 19 2025 14:30:00 (24-hour format)
  7. Enter the command a few seconds ahead of actual time, then press Enter when time matches
  8. The RTC is now synchronized. Ensure a CR1220 coin cell battery is installed for backup power.

5. Uploading Main Code

  1. Ensure the device is powered off (no USB, no battery)
  2. Insert microSD card into SD card slot
  3. Connect battery (if applicable)
  4. Connect USB cable to computer
  5. Open sketchbooks/feathergauge_code/feathergauge_code.ino
  6. Configure sampling parameters in user_config.h (see Configuration Options)
  7. Click Upload
    • If upload hangs, press the reset button immediately after clicking upload to enter the bootloader.
  8. Once upload completes, disconnect USB cable
  9. The red LED will flash 1-6 times then stop, indicating successful startup.

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

Configuration Options

Edit user_config.h before uploading to configure sampling behavior:

Continuous Sampling Mode

SAMPLE_FREQ = 16;  // Sampling frequency in Hz
BURST_SAMPLING = false;
BURST_SAMPLING_ONE_SAMPLE = false;
DELAY_START = false;

Burst Sampling Mode

SAMPLE_FREQ = 16;  // Frequency during burst
BURST_SAMPLING = true;
BURST_SAMPLING_ONE_SAMPLE = false;  // Set true for single sample per burst
writeSeconds = 30;   // Sampling duration (seconds)
sleepSeconds = 120;  // Sleep duration between bursts (seconds)
DELAY_START = false;

Single Sample Burst Mode

SAMPLE_FREQ = 1;  // Must be 1 Hz for single sample
BURST_SAMPLING = true;
BURST_SAMPLING_ONE_SAMPLE = true;
writeSeconds = 5
sleepSeconds = 120;
DELAY_START = false;

Battery Life Considerations:

  • Higher sampling frequencies reduce battery life
  • Burst sampling with longer sleep intervals extends battery life

Operation

Starting the Wave Gauge

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.

Data Format

File Naming

  • Format: MM-DD-YY.CSV (date when sampling began)
  • Example: 12-19-25.CSV for December 19, 2025

CSV Structure

Each file contains:

  • Header row: Wave gauge serial number and metadata
  • Data rows: Timestamp, pressure (mbar), temperature (°C)

Example CSV Output

W.G. Num: 01,Timestamp,Pressure [mbar],Temp [deg C],Battery [VDC]
2025/9/19,12:19:51:018,1006.20,26.94,4.47
2025/9/19,12:19:51:078,1006.30,26.95,4.47

Deployment Guidelines

Orientation

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

Depth Considerations for Wave Monitoring

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

  • Decay Coefficient (K): Want K ≈ 1.0 for target wave periods
  • Avoid: Placing sensors too high above seabed for short-period waves
  • Example: At 3m depth on seabed, wave periods ≤2s will not be detected

pressuredecayguide Figure 1. Deployment Guidance for Pressure Attenuation with Depth

Pre-Deployment Testing (Recommended)

  1. Allow gauge to sample in atmospheric pressure for 1-2 minutes
  2. Submerge all gauges in bucket of seawater (sensor at bottom)
  3. Sample for 1-2 minutes with consistent orientation
  4. Use these reference samples for minor calibration adjustments

Recovery

  1. Keep gauge sensor-down during recovery to prevent water intrusion
  2. ⚠️ Warning: If leak occurred, gauge may be under pressure. Do not point at self when opening.
  3. Inspect for water with sensor-down orientation
  4. If water present: Remove electronics, unplug battery, pour out water
  5. Do not reuse water-exposed batteries
  6. Allow to dry completely before reinserting electronics

Battery Life

Configuration Battery Capacity Estimated Life
Single sample burst (2 min interval) 4400 mAh ~2 months
Single sample burst (2 min interval) 10200 mAh >3 months
16 Hz continuous sampling 4400 mAh ~3 weeks
16 Hz continuous sampling 10500 mAh >1 month

LED Status Indicators

Normal Operation

Flash Count Meaning
1-6 flashes then off Normal - Program started successfully

Error Codes (Continuous Flashing)

Flash Count Meaning Solution
1 flash (repeating) SD Card Error - Not initialized Check SD card insertion; verify card format; try different card
2 flashes (repeating) File Creation Error - Cannot write to SD Check SD card has free space; verify card is not write-protected; card may be faulty

Troubleshooting

Board Not Recognized by Arduino IDE

  • Cause: Using power-only micro-USB cable
  • Solution: Use a data+power micro-USB cable. Check Device Manager (Windows) for COM port.

Date/Time Incorrect

Compilation Errors

  • Library not found: Close and reopen Arduino IDE after installing libraries
  • Board not selected: Ensure "Adafruit Feather 32u4" is selected in Tools → Board
  • Port not available: Check USB cable connection and try different port

Logger Not Working

  1. Upload simple test: File → Examples → Basics → Blink

    • If fails: Board hardware issue
    • If works: Check below

  2. Check microSD card:

    • Is it inserted correctly?
    • Using recommended 8GB card? (Large capacity cards may not be supported)
    • Is card formatted correctly?

  3. Check code configuration:

    • Verify all parameters in lines 1-50 are set correctly
    • Ensure DELAY_START = false

Sensor Values Don't Make Sense

  1. Check wiring: Ensure SCL and SDA are not reversed

Upload Hangs or fails"

  • Press the small black reset button on the board immediately after clicking "Upload".
  • This forces the board into bootloader mode

Post-processing

Data files contain absolute pressure readings. Post-processing steps:

Subtract atmospheric pressure to obtain gauge pressure

  • Use nearby atmospheric reference time-series (preferred)
  • Or use estimated average atmospheric pressure
  • Conversion: 1 millibar ≈ 1 cm water height

License

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.

Acknowledgments

Special thanks to:

  • Bret Webb at the University of South Alabama for his research that developed the feather wave gauge.
  • Jordan Cheung from the University of Washington for her help improving the wave gauge's software functionality.

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Implementation of a DIY RBR wave gauge at 10% of the cost

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