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The Feather 32u4 Adalogger is an all-in-one datalogger built around the ATmega32u4, with a built-in MicroSD card holder, USB connectivity, and LiPo battery c...

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The Feather 32u4 Adalogger is an all-in-one datalogger built around the ATmega32u4, with a built-in MicroSD card holder, USB connectivity, and LiPo battery charging. Ready to log data straight out of the box — just add a MicroSD card and start recording.

The ATmega32u4 runs at 8 MHz with 3.3V logic and includes native USB support, so it can act as a serial device, keyboard, mouse, or USB MIDI controller without needing a separate USB-serial chip. Built-in battery charging and automatic USB/battery power switching make it ideal for portable data logging projects.

Key Features

  • ATmega32u4 @ 8 MHz – 3.3V logic, 32KB flash, 2KB RAM
  • Native USB – Built-in USB bootloader, serial debugging, and HID device support
  • MicroSD Card Holder – For extensive data storage and reading
  • 20 GPIO Pins – Including 10 analogue inputs and 7 PWM outputs
  • Hardware Serial, I2C & SPI – Full peripheral support
  • Built-in LiPo Charger – 100 mA charging with status indicator LED
  • Battery Monitoring – Battery voltage routed to an analogue pin via divider
  • 3.3V Regulator – 500 mA peak current output
  • Pin #8 Green LED – Additional LED for logging status indication
  • Pin #13 Red LED – General-purpose blinking

Specifications

  • Dimensions – 51 × 23 × 8 mm (without headers)
  • Weight – 5.1 g
  • Mounting – 4 mounting holes

Also Available

Ideal For

  • Portable data logging and environmental monitoring
  • Sensor data recording to MicroSD card
  • Battery-powered field deployments

Package Contents

  • 1× Assembled and tested Feather 32u4 Adalogger
  • 1× Header set
Note: LiPo battery, MicroSD card, and USB cable are sold separately.

Jargon buster

Plain-language definitions for the technical terms used above.

3.3V regulator
A 3.3V regulator is a power circuit that provides a steady 3.3 volts for parts that need that supply voltage. On a breakout board, it can let the sensor run safely even when the connected microcontroller or power source uses a higher voltage.
ATmega328P
An 8-bit microcontroller chip used on many Arduino Uno-compatible boards. Knowing the controller uses an ATmega328P helps you understand its memory, speed, pin compatibility, and the Arduino sketches it can run.
Bootloader
Small starter software on a microcontroller that lets new code be uploaded before the main program runs. Knowing how to enter bootloader mode matters when you need to program the board or recover it after a faulty sketch.
GPIO
General-purpose input/output pins are microcontroller pins you can set in software to read signals, switch devices on and off, or connect to peripherals. The number of GPIO pins matters because it limits how many buttons, LEDs, sensors, and other parts you can wire directly to the board.
Headers
Rows of connector contacts on a fixed pitch (commonly 2.54 mm) used to link a board to a breadboard, jumper wires, or another board. They come as male pin headers and female socket headers; when a module ships with pre-soldered headers it can be used straight away, whereas bare pads require soldering the pins yourself.
HID
Human Interface Device is a USB device class used for keyboards, mice, gamepads and similar controls. If a board supports HID over USB, it can act like an input device to a computer without needing a custom driver.
I2C
I2C is a two-wire communication bus used by many sensors and small modules. It matters because several I2C devices can share the same two wires, but each device needs a compatible address and your controller must support I2C.
LED
A light-emitting diode (LED) is a small electronic component that emits light when current flows through it in the correct direction. Because it only conducts one way, its polarity matters, and a through-hole LED must be soldered the correct way around to light up.
LiPo
A LiPo (lithium polymer) battery is a rechargeable lithium battery widely used in portable projects because it is light and compact. LiPo cells need correct charging circuitry and careful handling to stay safe, so equipment that supports LiPo generally includes charging or protection hardware suited to that battery type.
microSD card
A microSD card is a small removable flash memory card used to store data such as audio, images, logs or program files. Its capacity and formatting (often FAT32 or exFAT) affect how much can be stored and whether the card needs preparing before use.
MIDI
MIDI is a standard way for electronic instruments, controllers, and software to send musical control messages such as notes, velocity, and timing. If a board supports MIDI, it can be triggered from keyboards, drum pads, sequencers, or other music gear rather than only from buttons or code.
native USB
Native USB means the microcontroller itself handles USB communication, rather than using a separate USB-to-serial chip. This matters for programming, debugging, and projects that need the board to act directly as a USB device.
PWM
Pulse Width Modulation is a way for a digital pin to simulate variable output power by switching on and off very quickly. It matters for controlling things like LED brightness, motor speed, or servo-style signals from a microcontroller pin.
RAM
RAM (random-access memory) is fast, temporary memory a device uses for working data while it is running; in its common volatile form, its contents are lost when power is removed. Some devices offer a mode that applies settings to RAM only, which is handy for testing changes temporarily because they are not stored permanently and disappear at power-off.
SPI
A fast serial communication bus often used for displays, memory cards, and sensors. It matters because SPI devices need specific pins for clock and data, plus a separate chip-select line for each device.
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