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