SMI230-Sensor-API and Sensor Driver

Table of Contents

• Introduction
• License
• Sensor interfaces
• Architecture
• Operation examples

Introduction

SMI230 is a system-in-package inertial measurement unit which offers accurate acceleration and angular rate measurements. Due to system-in-package approach of SMI230 (two sensors in single package), the gyroscope and acceleration data is acquired in a non-synchronized manner. However, synchronization between accelerometer and gyroscope can be achieved: The software modules in this repository are provided as reference for SMI230 users and shall demonstrate exemplarily the usage of the following features

• data synchronization.

Note: The sensor driver utilizes sensor api, which is following BMI08x sensor api available on github.

Note: The data synchronization feature utilizes sensor configuration, which is following BMI08x sensor configuration available on github.

License

See LICENSE file

Sensor interfaces

• I2C
• SPI

Architecture

                  User space
-------------------------------------------------------
                 |          |
               sysfs       dev
                 \          /
               input-subsystem
	             |
sensor_API <-- smi230_driver --> smi230_SPI/I2C_driver
                                           |
                                      SPI/I2C_bus
                                           |
-------------------------------------------------------
                  Hardware

Operation examples

1. Userspace The driver exposes a device file node under /dev/input/event*, which can be read as a normal Linux file. Tools like evtest can also be used for read data out. Eg.:

sudo evtest /dev/input/event0

The data will be displayed on the console with timestamp.

2. Sysfs The driver also exposes a set of sysfs nodes under /sys/devices/virtual/input/input*, where users can get information about the sensor and also control the sensor. Eg.:

# read the chip id
cat /sys/devices/virtual/input/input0/chip_id

# read the synced acc data 
cat /sys/devices/virtual/input/input0/data_sync

# read the asynced acc data 
cat /sys/devices/virtual/input/input0/acc_value

# read the gyro data 
cat /sys/devices/virtual/input/input0/gyro_value

# read the acc power config 
cat /sys/devices/virtual/input/input0/acc_pw_cfg

# set the acc power config active 
echo 0 > /sys/devices/virtual/input/input0/acc_pw_cfg

# set the acc power config suspend 
echo 3 > /sys/devices/virtual/input/input0/acc_pw_cfg