177 lines
5.3 KiB
Plaintext
177 lines
5.3 KiB
Plaintext
Kernel driver
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Author: Invensense <http://invensense.com>
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Table of Contents:
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==================
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- Description
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- Integrating the Driver in the Linux Kernel
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- Board and Platform Data
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> Platform Data
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- Board File Modifications for compass
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> AMI306
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> YAS530/532/533
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- IIO Subsystem
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> Communicating with the Driver in Userspace
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- Streaming Data to an Userspace Application
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- Test Applications
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> Running Test Applications with AMI306 or YAS53x
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Description
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===========
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This document describes how to install the Invensense device driver for AMI306
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and YAS53x series compass chip into a Linux kernel. The Invensense driver
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currently supports the following sensors:
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- AMI306
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- YAS530
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- YAS532
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- YAS533
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Please refer to the appropriate product specification
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document for further information regarding the slave address.
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The following files are included in this package:
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- Kconfig
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- Makefile
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- inv_ami306_core.c
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- inv_ami306_ring.c
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- inv_ami306_trigger.c
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- inv_ami306_iio.h
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- inv_yas53x_core.c
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- inv_yas53x_ring.c
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- inv_yas53x_trigger.c
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- inv_yas53x_iio.h
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Integrating the Driver in the Linux Kernel
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==========================================
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Please add the files as follows:
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- Add all above files to drivers/staging/iio/magnetometer/inv_compass
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(another directory is acceptable, but this is the recommended destination)
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In order to see the driver in menuconfig when building the kernel, please
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make modifications as shown below:
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modify "drivers/staging/iio/magnetometer/Kconfig" with:
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>> source "drivers/staging/iio/magnetometer/inv_compass/Kconfig"
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modify "drivers/staging/iio/magnetometer/Makefile" with:
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>> obj-y += inv_compass/
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Board and Platform Data
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=======================
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In order to recognize the Invensense device on the I2C bus, the board file must
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be modified.
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The i2c_board_info instance must be defined as shown below.
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Platform Data
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-------------
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The platform data (orientation matrix and secondary bus configurations) must be
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modified as show below, according to your particular platform configuration.
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Board File Modifications for Secondary I2C Configuration
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========================================================
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For the Panda Board, the board file can be found at
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arch/arm/mach-omap2/board-omap4panda.c.
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Please modify the pertinent baord file in your system according to the examples
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shown below:
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AMI306
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-------------------------------------------------
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static struct mpu_platform_data compass_data = {
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.orientation = { 0, 0, 1,
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0, 1, 0,
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1, 0, 0 },
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};
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static struct i2c_board_info __initdata chip_board_info[] = {
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{
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I2C_BOARD_INFO("ami306", 0x0E),
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.platform_data = &compass_data,
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},
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};
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YAS53x(Use YAS532 as an example)
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-------------------------------------------------
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static struct mpu_platform_data compass_data = {
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.orientation = { 0, -1, 0,
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1, 0, 0,
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0, 0, 1 },
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};
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static struct i2c_board_info __initdata compass_board_info[] = {
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{
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I2C_BOARD_INFO("yas532", 0x2E),
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.platform_data = &compass_data,
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},
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};
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IIO subsystem
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=============
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A successful installation will create the following two new directories under
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/sys/bus/iio/devices:
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- iio:device0
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- trigger0
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Also, a new file, "iio:device0", will be created in the /dev/ diretory.
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(if you have more than one IIO device, the file will be named "iio:deviceX",
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where X is a number)
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Communicating with the Driver in Userspace
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------------------------------------------
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The driver generates several files in sysfs upon installation.
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These files are used to communicate with the driver. The files can be found
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at /sys/bus/iio/devices/iio:device0 (or ../iio:deviceX as shown above).
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A brief description of the pertinent files for each Invensense device is shown
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below:
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AMI306
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--------
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compass_matrix (read-only)
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--show the orientation matrix obtained from the board file.
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sampling_frequency(read and write)
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--show and change the sampling rate of the sensor.
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YAS53x
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---------------------
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YAS53x has all the attributes AMI306 has. It has one more additional attribute:
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overunderflow(read-only)
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--value 1 shows an overflow or underflow happens. Need to write into it to make
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it zero.
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Streaming Data to an Userspace Application
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==========================================
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When streaming data to an userspace application, we recommend that you access
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compass data via /dev/iio:device0.
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Please follow the steps below to read data at a constant rate from the driver:
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1. Write the desired output rate to sampling_frequency.
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2. Write 1 to enable to turn on the event.
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3. Read /dev/iio:device0 to get a string of gyro/accel/compass data.
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4. Parse this string to obtain each compass element.
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Test Applications
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=================
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A test application is located under software/simple_apps/mpu_iio.
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This application is stand-alone in that it cannot be run concurrently with other
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entities trying to access the device node(s) or sysfs entries; in particular,
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the
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Running Test Applications
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---------------------------------------------------------
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To run test applications with AMI306 or YAS53x devices,
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please use the following commands:
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1. for ami306:
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mpu_iio -n ami306 -c 10 -l 3
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2. for yas532:
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mpu_iio -n yas532 -c 10 -l 3
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Please use mpu_iio.c and iio_utils.h as example code for your development
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purposes.
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