SparkFun
SparkFun OpenLog
The SparkFun OpenLog is an open-source serial data logger based on the ATmega328 running at 16 MHz. It logs incoming serial data directly to a microSD card, ...
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The SparkFun OpenLog is an open-source serial data logger based on the ATmega328 running at 16 MHz. It logs incoming serial data directly to a microSD card, supporting cards from 64 MB to 64 GB in FAT16 or FAT32 format. Simply connect a serial line from your project to the OpenLog, and all transmitted data is stored to the card as text files.
The OpenLog draws approximately 5 mA on average, rising to around 6 mA when actively writing a 512-byte buffer. It supports configurable baud rates and is well suited for long-term data acquisition, debugging, and any application where a record of serial output is needed.
Key Features
- Simple Serial Interface – Connect via serial TX/RX to log data automatically
- microSD Storage – Supports 64 MB to 64 GB cards (FAT16/FAT32)
- ATmega328 Processor – 16 MHz with open-source firmware
- Low Power – Approximately 5–6 mA during operation
- Configurable Baud Rate – Adjustable via configuration file on the SD card
- Automatic File Creation – Creates new log files on each power cycle
Specifications
- Microcontroller – ATmega328 at 16 MHz
- Storage – microSD (64 MB – 64 GB, FAT16/FAT32)
- Current Draw – ~5 mA average, ~6 mA peak (during write)
- Default Baud Rate – 9600 bps (configurable)
- Logic Level – 3.3 V
Ideal For
- Serial data logging and scientific data acquisition
- Debugging and black-box recording of project output
- Remote or unattended sensor data collection
- Flight data recorders and environmental monitoring
Package Contents
- 1× SparkFun OpenLog
Resources
Jargon buster
Plain-language definitions for the technical terms used above.
- baud
- Baud is the signalling rate of a serial connection, often used as the speed setting for UART communication. Matching the baud rate matters because both connected devices must use the same setting for readable data.
- microcontroller
- A microcontroller is a small computer on a single chip that runs a stored program and controls connected inputs and outputs such as buttons, sensors, displays and communication interfaces. In a device built around one, it is the part that executes the code and coordinates the device's behaviour.
- 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.
- RX
- RX means receive, usually showing data being received by the board. An RX indicator LED can help with troubleshooting USB or serial communication.
- TX
- TX means transmit, usually showing data being sent from the board. A TX indicator LED can help you see when the board is communicating or uploading code.
Find this product in
Brands
OpenLog v1.5 Schematic
Schematic · 48.4 KB · Click any page to view full size
Supplier page — sparkfun.com
Supplier Description · 798.0 KB · Click any page to view full size
Resources & Downloads
Guides, code examples, and more
Source Code
Open-source libraries, firmware & example projects for this product
140fe56
over 4 years ago
· 171 commits
- Binaries Add binaries and bootload tools. over 4 years ago
- Documentation Updating directory structure, updating fritzing documentation over 10 years ago
- firmware Terminate filename strings and increase any array by 1 that uses strcpy_P. over 4 years ago
- hardware Adding 'read firmware version' example about 8 years ago
- Libraries Updating serialport lib to work with recent Arduino releases. almost 10 years ago
- Production added bottom side panel fiducials over 10 years ago
- .gitattributes Repo cleanup, readme cleanup over 10 years ago
- .gitignore Rewriting examples. over 8 years ago
- CHANGELOG.md Updating changelog. Removing extraneous code from OpenLog_Minimal. over 10 years ago
- ISSUE_TEMPLATE.md Fix spelling about 8 years ago
- LICENSE.md Repo cleanup, readme cleanup over 10 years ago
- README.md Update README.md over 6 years ago
Related Tutorials
Free guides on learn.littlebird.com.au
