$24.95 ea.
$24.95 ea.

OpenLog is an open source data logger. Simple to use, simple to change.

Description [Hide]

SparkFun doesn't mess around when they have something they want to make happen. There's been too many projects needing a simple, effective serial datalogger, so hence: The OpenLog - an open source data logger!

The OpenLog is a serial logger that just works. Power it up and it will starts logging any received serial data at 9600bps. Sending Ctrl+z will drop out of logging and in to command mode. 'new' will create a new file. 'md' makes a directory. '?' brings up the list of commands. OpenLog doesn't do everything, but it does log serial streams extremely well. Here's an example of how it is used:

>new testfile.txt
>append testfile.txt

That's it! OpenLog firmware is open source and is based on Roland Riegel's FAT library. OpenLog currently supports FAT16 (up to 2GB microSD cards). (FAT32 work is underway - stay tuned... or help!)

All the design files (schematic, PCB layout, firmware) are open source released under the CC-SA v3 license and are available through Github.


  • Log to low-cost microSD cards up to 2GB
  • Simple command interface
  • Three modes:
    • NewLog creates a new log every power up and immediately starts logging
    • SeqLog appends a file called "SeqLog.txt" at every power up and immediately starts logging
    • Command mode starts OpenLog at a command prompt at power up
  • Configurable baud rates (2400 to 115200bps)
  • Doesn't drop characters even at full-blast 115200bps
  • Power, ground, and RX-I are the minimum connections
  • Reprogrammable ATmega328 using the standard STK500 serial bootloader
  • Two LEDs indicate writing status
  • Input voltage from 3.3V to 12V
  • 8mA idle, 18mA at maximum recording rate

Dimensions: 0.16 x 0.6 x 0.75" (4 x 15 x 19mm)


  • Homepage
  • Command Set
  • Datasheet
  • Datalogger comparison

The OpenLog project is housed on github! Please see the wiki for the most up-to-date firmware, feature requests, files, and datasheet specs.

Documentation [Hide]

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