About

Library for the LSM9DS1 from ST Microelectronics. Library makes use of the Linux platform device driver "spidev". The library was originally written for the RaspberryPi B+.

The LSM9DS1 provides 9 degrees of freedom (9-DOF), a 3 axis accelerometer, gyroscope and magnetometer. The accelerometer supports ± 2, 4, 8, or 16 g, the gyroscope supports ± 245, 500, and 2000 °/s, and the magnetometer has full-scale ranges of ± 2, 4, 12, or 16 gauss. It is equipped with a digital interface supporting both I2C and SPI.

Install

Please see the releases to obtain prebuilt versions for the raspberrypi 3B+. Always use the latest version as only alpha version are released.

Install using RPM

Remember to replace v0.4.0-alpha with the appropriate version.

rpm -ivh liblsm9ds1-v0.4.0-alpha-raspberrypi3.rpm

Uninstall

Uninstall using RPM

Remember to replace v0.4.0-alpha-1 with the appropriate version.

rpm -e liblsm9ds1-v0.4.0_alpha-1

API Documentation

You can find the documentation here.

The API is simple to use. Here is a quick example of reading from the accelerometer.

C API

#include <lsm9ds1.h>
#include <stdio.h>
#include <stdlib.h>
int main() {
    lsm9ds1_status_t status = LSM9DS1_UNKNOWN_ERROR;
    lsm9ds1_device_t lsm9ds1 = {0};
    status = lsm9ds1_init(&lsm9ds1, LSM9DS1_SPI_BUS, LSM9DS1_ACCELRANGE_8G, LSM9DS1_MAGGAIN_8GAUSS, LSM9DS1_GYROSCALE_500DPS);
    if(status < 0) {
        fprinf(stderr, "Error initializing lsm9ds1!\n");
        exit(EXIT_FAILURE);
    }
    status = lsm9ds1.update_accel(lsm9ds1);
    if(status < 0) {
        fprintf(stderr, "Error reading accelerometer!\n");
        exit(EXIT_FAILURE);
    }
    printf("Accelerometer x: %f\n", lsm9ds1.converted_data.accelerometer.x);
    printf("Accelerometer y: %f\n", lsm9ds1.converted_data.accelerometer.y);
    printf("Accelerometer z: %f\n", lsm9ds1.converted_data.accelerometer.z);
    return EXIT_SUCCESS;
}

Dependencies

This library depends on the cjson library by Dave Gamble. Please follow the installation steps to build for your system.

Building

There are 2 options when building the LSM9DS1 Library.

Build for release When building for release you will build the source code, doxygen documentation, CUnit tests, and package for the RPM format.
Build for debug When building for debug purposes you will build the source code with debugging symbols and additional print statements as well as the CUnit tests.

You MUST have the SDK sourced to create a cross-compiled build for the raspberrypi system. (If you don't intend to build for this system you can skip this step.)

```bash source /opt/poky/2.6.2/environment-setup-cortexa7t2hf-neon-vfpv4-poky-linux-gnueabi ```

Use the build shell script. This will use cmake and make to build for your system.

If building for release.

```bash ./build.sh release ```

If building for debugging purposes.

```bash ./build.sh debug ```

Testing

This project uses the the CUnit Testing Framwork. Tests can be run by running the lms9ds1_test program installed in the /usr/bin directory.

Debugging

You can remotely debug the application on the raspberry pi using gdbserver. A nice application to aid in debugging is gdbgui. You can install from the instructions foun here. In ubuntu also make sure you install gdb-multiarch if using ubuntu.

sudo apt install gdb-multiarch

On the remote system, start the server.

```bash gdbserver localhost:5000 lsm9ds1_test ```

On the local machine start gdbgui.

```bash gdbgui -r -g gdb-multiarch ```

RaspBerryPi 3 B + Schematic

LSM9DS1 Pinout

Pin Label	Pin Function	Notes
GND	Ground	0V voltage supply
VDD	Power Supply	Supply voltage to the chip. Should be regulated between 2.4V and 3.6V.
SDA	SPI: MOSI I2C: Serial Data	SPI: Device data in (MOSI) I2C: Serial data (bi-directional)
SCL	Serial Clock	I2C and SPI serial clock.
DEN	Gyroscope Data Enable	Mostly unknown. The LSM9DS1 datasheet doesn't have much to say about this pin.
INT2	Accel/Gyro Interrupt 2	INT1 and INT2 are programmable interrupts for the accelerometer and gyroscope. They can be set to alert on over/under thresholds, data ready, or FIFO overruns.
INT1	Accel/Gyro Interrupt 1
INTM	Magnetometer Interrupt	A programmable interrupt for the magnetometer. Can be set to alert on over-under thresholds.
RDY	Magnetometer Data Ready	An interrupt indicating new magnetometer data is available. Non-programmable.
CS M	Magnetometer Chip Select	This pin selects between I2C and SPI on the magnetometer. Keep it HIGH for I2C, or use it as an (active-low) chip select for SPI. HIGH (1): SPI idle mode / I2C enabled LOW (0): SPI enabled / I2C disabled.
CS AG	Accel/Gyro Chip Select	This pin selects between I2C and SPI on the accel/gyro. Keep it HIGH for I2C, or use it as an (active-low) chip select for SPI. HIGH (1): SPI idle mode / I2C enabled LOW (0): SPI enabled / I2C disabled.
SDO M	SPI: Magnetometer MISO I2C: Magnetometer Address Select	In SPI mode, this is the magnetometer data output (SDO_M). In I2C mode, this selects the LSb of the I2C address (SA0_M)
SDO AG	SPI: Accel/Gyro MISO I2C: Accel/Gryo Address Select	In SPI mode, this is the accel/gryo data output (SDO_AG). In I2C mode, this selects the LSb of the I2C address (SA0_AG)