# Adafruit Feather 32u4 Adalogger > Feather-format ATmega32u4 data logger at 8 MHz, 3.3V with onboard microSD slot, LiPo charging, native USB, 20 GPIO, and 100mA charger — built for portable data logging applications. ## Quick Facts - **Brand:** Adafruit - **Board Type:** dev-board - **Price:** ~$21.95 - **Product Readiness:** developer - **CPU:** ATmega32u4 @ 8 MHz - **CPU Architecture:** AVR - **CPU Cores:** 1 - **RAM:** 2 KB - **Flash:** 32 KB - **Power:** 3.7V LiPo via JST or 5V Micro USB - **Operating Voltage:** 3.3V - **Dimensions:** 51 × 23 mm - **Weight:** 5.1g - **SD Card:** microSD ## Open Source - **Firmware:** Yes - **Schematics:** Yes - **PCB Layout:** Yes ## Compatible Firmware arduino, platformio ## Use Cases - data-logging - portable - battery-powered - environmental-monitoring - iot ## Components - **ATmega32u4** (mcu): 8-bit AVR with native USB at 8 MHz, 32KB flash, 2KB SRAM — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fww1.microchip.com%2Fdownloads%2Fen%2FDeviceDoc%2FAtmel-7766-8-bit-AVR-ATmega16U4-32U4_Datasheet.pdf&ref=openhardware.directory&product=adafruit-feather-32u4-adalogger&source=md-export) - **MCP73831** (charger): Microchip MCP73831 100mA LiPo charge management IC — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fww1.microchip.com%2Fdownloads%2Fen%2FDeviceDoc%2F20001984g.pdf&ref=openhardware.directory&product=adafruit-feather-32u4-adalogger&source=md-export) ## Protocols - **UART**: TX: D1, RX: D0 - **SPI**: MOSI: D16, MISO: D14, SCK: D15, SS: D10, SD_CS: D4 - **I2C**: SDA: D2, SCL: D3 - **USB** ## GPIO Map | Pin | Name | Type | Functions | |-----|------|------|-----------| | D0 | UART RX, External Interrupt 2 | UART | digital-input, digital-output, interrupt | | D1 | UART TX, External Interrupt 3 | UART | digital-input, digital-output, interrupt | | D2 | I2C SDA, External Interrupt 1 | I2C | digital-input, digital-output, interrupt | | D3 | I2C SCL, PWM, External Interrupt 0 | I2C | digital-input, digital-output, pwm, interrupt | | D4 | microSD Chip Select, Analog Input (A6) | SPI | digital-input, digital-output, analog-input | | D5 | Digital I/O, PWM | — | digital-input, digital-output, pwm | | D6 | Digital I/O, Analog Input (A7), PWM | — | digital-input, digital-output, analog-input, pwm | | D7 | Digital I/O, External Interrupt 6 | — | digital-input, digital-output, interrupt | | D8 | Green status LED (logging indicator) | — | digital-output | | D9 | Battery voltage monitor, Analog Input (A9), PWM | — | digital-input, digital-output, analog-input, pwm | | D10 | SPI SS, Analog Input (A10), PWM | SPI | digital-input, digital-output, analog-input, pwm | | D11 | Digital I/O, PWM | — | digital-input, digital-output, pwm | | D12 | Digital I/O, Analog Input (A11) | — | digital-input, digital-output, analog-input | | D13 | Onboard red LED, PWM | — | digital-input, digital-output, pwm | | D14 | SPI MISO | SPI | digital-input, digital-output | | D15 | SPI SCK | SPI | digital-input, digital-output | | D16 | SPI MOSI | SPI | digital-input, digital-output | | A0 | Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A1 | Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A2 | Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A3 | Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A4 | Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A5 | Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | ## Available Software - **[Arduino IDE]()** (open-source) - **[PlatformIO]()** (open-source) ## Description ## Overview The Adafruit Feather 32u4 Adalogger extends the Feather 32u4 Basic Proto with an onboard microSD card slot, transforming it into a self-contained data logging platform. Based on the ATmega32u4 at 8 MHz with 3.3V logic, it maintains the Feather's compact 51 × 23 mm footprint and 5.1g weight while adding persistent storage capabilities. The microSD slot enables logging sensor readings, timestamps, and other data directly to removable storage without a computer. A green LED on pin 8 provides a status indicator alongside the standard red LED on pin 13. All other hardware specifications match the Feather 32u4 Basic Proto: 32KB flash, 2KB SRAM, 20 GPIO, 7 PWM, 10 analog inputs, hardware Serial/I2C/SPI, and native USB through the ATmega32u4. Battery power is managed by an integrated 100mA LiPoly charger with a JST connector for standard 3.7V LiPo batteries. The 3.3V regulator provides 500mA peak output. Automatic switchover between USB and battery ensures continuous operation during field deployment. The Adalogger is well suited for environmental monitoring, GPS tracking with SD logging, time-series data collection, and any project requiring long-term data capture in a portable, battery-powered form factor. It stacks with all standard FeatherWing accessories through the Feather header system. ## Where to Buy - [Adafruit](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F2795&ref=openhardware.directory&product=adafruit-feather-32u4-adalogger&source=md-export) — 21.95 ## Resources - [product](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F2795&ref=openhardware.directory&product=adafruit-feather-32u4-adalogger&source=md-export) - [wiki](https://openhardware.directory/r?to=https%3A%2F%2Flearn.adafruit.com%2Fadafruit-feather-32u4-adalogger&ref=openhardware.directory&product=adafruit-feather-32u4-adalogger&source=md-export) ## Tags `feather`, `atmega32u4`, `data-logging`, `microsd`, `lipo`, `adafruit`, `adalogger` ## Images ![Adafruit Feather 32u4 Adalogger](https://nbg1.your-objectstorage.com/openhardware-directory/entities/adafruit-feather-32u4-adalogger/4d2e384890a0.jpg) ![Adafruit Feather 32u4 Adalogger](https://nbg1.your-objectstorage.com/openhardware-directory/entities/adafruit-feather-32u4-adalogger/17e987a87636.jpg) --- [View full device page](https://openhardware.directory/devices/adafruit-feather-32u4-adalogger)