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Arduino library for Pololu L3G4200D and L3GD20 boards

branch: master

Update README.textile

added links to other programs that use this library
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Octocat-spinner-32 L3G L3G: updated library to get it to work with L3GD20H February 05, 2014
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Arduino library for Pololu L3G boards

Version: 1.2.2
Release Date: 2014-02-05


This is a library for the Arduino that interfaces with L3GD20H, L3GD20, and L3G4200D gyros on Pololu boards. It makes it simple to read the raw gyro data from these boards:

Getting Started


Download the archive from GitHub, decompress it, and move the “L3G” folder into the “libraries” subdirectory inside your Arduino sketchbook directory. You can view your sketchbook location by selecting File→Preferences in the Arduino environment; if there is not already a “libraries” folder in that location, you should create it yourself. After installing the library, restart the Arduino environment so it can find the L3G library and its example.


Make the following connections with wires between the Arduino and the L3G board:

Arduino Uno R3, Leonardo, Mega 2560

Arduino      L3G board
     5V  ->  VIN
    GND  ->  GND
    SDA  ->  SDA
    SCL  ->  SCL

Arduino Micro

Arduino      L3G board
     5V  ->  VIN
    GND  ->  GND
      2  ->  SDA
      3  ->  SCL

Arduino Uno (up to R2), Duemilanove, etc.

Arduino      L3G board
     5V  ->  VIN
    GND  ->  GND
     A4  ->  SDA
     A5  ->  SCL

Example Programs

Open an example code sketch by selecting File→Examples→L3G→example_name


This program continuously reads the gyro, communicating the readings over the serial interface. You can display the readings with the Arduino Serial Monitor.

Example output:

G X: 188 Y: -10 Z: -47
G X: 138 Y: -40 Z: -26
G X: 110 Y: -55 Z: 4

Other Library Applications

These programs make use of the L3G library but are not included with in the library archive or repository.

MinIMU-9 + Arduino AHRS
This sketch allows an Arduino connected to a MinIMU-9 or AltIMU-10 to function as an attitude and heading reference system, calculating estimated roll, pitch, and yaw angles from sensor readings that can be visualized with a 3D test program on a PC. It is based on the work of Jordi Munoz, William Premerlani, Jose Julio, and Doug Weibel.
Pololu_Open_IMU by mikeshub
This is an alternative AHRS implementation that uses the Madgwick algorithm.
ascii_graph by drewtm
This sketch outputs a text-based graph of LSM303 accelerometer and L3G gyro data, providing a quick way to check whether the sensors are working as expected.

Library Reference

vector g
The last values read from the gyro.
bool init(byte device, byte sa0)
Initializes the library with the device being used (L3G4200D or L3GD20) and the state of the SA0 (slave address least significant bit) pin. Constants for these arguments are defined in L3G.h. Both of these arguments are optional; if they are not specified, the library will try to automatically detect the device and slave address, and it will return a boolean indicating whether the autodetection was succesful.
Note: Automatic detection of the device type currently does not work with the Arduino Due because of issues with its Wire library. To work around this, specify the device and SA0 state manually (e.g. init(L3GD20_DEVICE, L3G_SA0_HIGH)).
void enableDefault(void)
Turns on the gyro in the default configuration.
void writeReg(byte reg, byte value)
Writes a gyro register with the given value. Register address constants are defined in L3G.h.
byte readReg(byte reg)
Reads a gyro register and returns the value read.
void read(void)
Takes a reading from the gyro and stores the values in the vector g.

Differences from the L3G4200D library

This library is very similar to our earlier L3G4200D library, which is not compatible with the L3GD20. Besides the name change, the main difference in this library is that you need to call the init() function before using any of the other library functions, typically from within the Arduino setup() function. While the older library only works with the Pololu boards’ default gyro slave address of 1101001b, this library allows you to specify the slave address with the init() function.

Version History

  • 1.2.2 (2014-02-05): Added support for L3GD20H.
  • 1.2.1 (2012-10-31): Cast sensor readings to 16-bit ints for better portability.
  • 1.2.0 (2012-07-06): Renamed library to L3G and added support for L3GD20.
  • 1.1.0 (2011-12-12): Arduino 1.0 compatibility.
  • 1.0.0 (2011-09-14): Original release of L3G4200D library.
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