Welcome to EnviroDIY, a community for do-it-yourself environmental science and monitoring. EnviroDIY is part of WikiWatershed, an initiative of Stroud Water Research Center designed to help people advance knowledge and stewardship of fresh water.
New to EnviroDIY? Start here

Getting Started With the Mayfly Data Logger

Mayfly 1.0 board

The EnviroDIY Mayfly Data Logger is a powerful, user-programmable microprocessor board that is fully compatible with the Arduino IDE software. It features the ATmega1284p processor, which is much more powerful than the 328p chip found on most other Arduino boards. It has 4 times more flash memory for sketches, 8 times more RAM, and almost twice as many input pins.

Features of the Mayfly v1.0:

  • 128K Flash memory, 16K RAM
  • 28 digital I/O pins, 8 analog pins, plus 4 additional high-resolution ADC pins and 4 Aux I/O pins
  • 2 serial UART ports
  • microSD memory card socket
  • Additional 8Mb onboard flash memory module
  • Onboard realtime clock (RTC) (DS3231)
  • Solar Lipo battery charging
  • Low power consumption (6.5 mA when on but idle, 0.27-0.43 mA when in sleep)
  • Bee module socket
  • 2 user-programmable LEDs, 1 user-programmable pushbutton
  • 3.3v main board voltage, additional 5-volt and 12-volt boost circuity for external devices
  • Two 20-pin headers for accessing all available I/O pins
  • 7 Grove-style sockets for easy connections to sensors and devices and 2 Qwiic sockets
  • Two on-board sensors:  digital humidity/temperature sensor and analog light sensor

The memory card socket, RTC, and solar charging features make it very easy to use this board for data logging and low-power operation. But it can also be used by itself, or with a wide variety of devices and accessories.  The Mayfly board can be powered by a 3.7v lithium battery or through the USB-C port. Programming can be done through the USB-C port or via the FTDI header.

Hardware Details

Find information about the Mayfly Data Logger and its features, with descriptions about the various connectors and sockets, and the schematic diagram.

Software Instructions

Follow these instructions for adding the Mayfly Data Logger to your Arduino IDE, then you can program it with some of these sample code sketches.

EnviroDIY Monitoring Station Manual

Read the comprehensive manual for building, programming, deploying, and maintaining an EnviroDIY Monitoring Station.

Monitor My Watershed

Monitor My Watershed® is an online data portal that lets you discover and map monitoring data and share your EnviroDIY monitoring data with the world.


If you don’t find the answers on the Hardware and Software pages or in the EnviroDIY Monitoring Station Manual, help the community out by posting on the dedicated Mayfly Data Logger forum.

All content on EnviroDIY is licensed as Creative Commons Attribution-ShareAlike 4.0. Hardware designs on EnviroDIY are released under the CERN Open Hardware License 1.2. Alternative licenses are available. Find our sketches and documentation on GitHub

Purchase Boards and Kits in our EnviroDIY Shop

Please note: at this time we are unable to sell or ship the Mayfly Data Logger outside of the United States.

Mayfly 1.0 board

Mayfly Data Logger Board

EnviroDIY Mayfly Starter Kit

Mayfly Data Logger Starter Kit