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ADIS16400 IIO惯性测量组合Linux驱动程序

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资料介绍

This version (23 Feb 2017 13:33) was approved by Lars-Peter Clausen.The Previously approved version (31 Aug 2015 11:12) is available.

ADIS16400 IIO Inertial Measurement Unit Linux Driver

Supported Devices

Evaluation Boards

Description

This is a Linux industrial I/O (IIO) subsystem driver, targeting serial interface Inertial Measurement Units (IMU). The industrial I/O subsystem provides a unified framework for drivers for many different types of converters and sensors using a number of different physical interfaces (i2c, spi, etc). See IIO for more information.

Source Code

Status

Source	Mainlined?
git	Yes

Files

Function	File
driver	drivers/iio/imu/adis16400_core.c
driver	drivers/iio/imu/adis16400_ring.c
driver	drivers/iio/imu/adis16400_trigger.c
include	drivers/iio/imu/adis16400.h

Declaring SPI slave devices

Unlike PCI or USB devices, SPI devices are not enumerated at the hardware level. Instead, the software must know which devices are connected on each SPI bus segment, and what slave selects these devices are using. For this reason, the kernel code must instantiate SPI devices explicitly. The most common method is to declare the SPI devices by bus number.

This method is appropriate when the SPI bus is a system bus, as in many embedded systems, wherein each SPI bus has a number which is known in advance. It is thus possible to pre-declare the SPI devices that inhabit this bus. This is done with an array of struct spi_board_info, which is registered by calling spi_register_board_info().

For more information see: Documentation/spi/spi-summary

21 Oct 2010 16:10

Depending on the converter IC used, you may need to set the modalias accordingly, matching your part name. It may also required to adjust max_speed_hz. Please consult the datasheet, for maximum spi clock supported by the device in question.

static struct spi_board_info board_spi_board_info[] __initdata = {
#if defined(CONFIG_ADIS16400) /
	|| defined(CONFIG_ADIS16400_MODULE)
	{
		.modalias = "adis16400",
		.max_speed_hz = 1000000,     /* max spi clock (SCK) speed in HZ */
		.bus_num = 0,
		.chip_select = 1, /* CS, change it for your board */
		.platform_data = NULL, /* No spi_driver specific config */
		.mode = SPI_MODE_3,
		.irq = IRQ_PF5,
	},
#endif
 
};

static int __init board_init(void)
{
	[--snip--]
 
	spi_register_board_info(board_spi_board_info, ARRAY_SIZE(board_spi_board_info));
 
	[--snip--]
 
	return 0;
}
arch_initcall(board_init);

Adding Linux driver support

Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)

The ADIS16400 Driver depends on CONFIG_SPI

Linux Kernel Configuration
	Device Drivers  --->
		<*>     Industrial I/O support --->
		    --- Industrial I/O support
		    *** Inertial measurement units ***
		    [--snip--]
			    <*>   Analog Devices ADIS16400 and similar IMU SPI driver
		    [--snip--]

Hardware configuration

Driver testing

Each and every IIO device, typically a hardware chip, has a device folder under /sys/bus/iio/devices/iio:deviceX. Where X is the IIO index of the device. Under every of these directory folders reside a set of files, depending on the characteristics and features of the hardware device in question. These files are consistently generalized and documented in the IIO ABI documentation. In order to determine which IIO deviceX corresponds to which hardware device, the user can read the name file /sys/bus/iio/devices/iio:deviceX/name. In case the sequence in which the iio device drivers are loaded/registered is constant, the numbering is constant and may be known in advance.

02 Mar 2011 15:16

This specifies any shell prompt running on the target

root:/> cd /sys/bus/iio/devices/
root:/sys/bus/iio/devices> ls
iio:device0  trigger0

root:/sys/bus/iio/devices> cd iio:device0
root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> ls -l
drwxr-xr-x    2 root     root             0 Jan  4 00:03 buffer
-r--r--r--    1 root     root          4096 Jan  4 00:03 dev
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_accel_filter_low_pass_3db_frequency
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_accel_scale
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_accel_x_calibbias
-r--r--r--    1 root     root          4096 Jan  4 00:03 in_accel_x_raw
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_accel_y_calibbias
-r--r--r--    1 root     root          4096 Jan  4 00:03 in_accel_y_raw
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_accel_z_calibbias
-r--r--r--    1 root     root          4096 Jan  4 00:03 in_accel_z_raw
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_anglvel_filter_low_pass_3db_frequency
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_anglvel_scale
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_anglvel_x_calibbias
-r--r--r--    1 root     root          4096 Jan  4 00:03 in_anglvel_x_raw
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_anglvel_y_calibbias
-r--r--r--    1 root     root          4096 Jan  4 00:03 in_anglvel_y_raw
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_anglvel_z_calibbias
-r--r--r--    1 root     root          4096 Jan  4 00:03 in_anglvel_z_raw
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_magn_filter_low_pass_3db_frequency
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_magn_scale
-r--r--r--    1 root     root          4096 Jan  4 00:03 in_magn_x_raw
-r--r--r--    1 root     root          4096 Jan  4 00:03 in_magn_y_raw
-r--r--r--    1 root     root          4096 Jan  4 00:03 in_magn_z_raw
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_temp0_offset
-r--r--r--    1 root     root          4096 Jan  4 00:03 in_temp0_raw
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_temp0_scale
-r--r--r--    1 root     root          4096 Jan  4 00:03 in_voltage0_supply_raw
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_voltage0_supply_scale
-r--r--r--    1 root     root          4096 Jan  4 00:03 in_voltage1_raw
-rw-r--r--    1 root     root          4096 Jan  4 00:03 in_voltage1_scale
-r--r--r--    1 root     root          4096 Jan  4 00:03 name
drwxr-xr-x    2 root     root             0 Jan  4 00:03 power
-rw-r--r--    1 root     root          4096 Jan  4 00:03 sampling_frequency
drwxr-xr-x    2 root     root             0 Jan  4 00:03 scan_elements
lrwxrwxrwx    1 root     root             0 Jan  4 00:03 subsystem -> ../../../../../bus/iio
drwxr-xr-x    2 root     root             0 Jan  4 00:03 trigger
-rw-r--r--    1 root     root          4096 Jan  4 00:03 uevent
root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0>

ADIS16400 device attributes

For a detailed description please see: Documentation/ABI/testing/sysfs-bus-iio

3-Axis Accelerometer related device files	Description
in_accel_filter_low_pass_3db_frequency	Bandwidth for the accelerometer channels.
in_accel_scale	Scale for the accelerometer channels.
in_accel_x_calibbias	Calibration offset for the X-axis accelerometer channel.
in_accel_x_raw	Raw X-axis accelerometer channel value.
in_accel_y_calibbias	Calibration offset for the Y-axis accelerometer channel.
in_accel_y_raw	Raw Y-axis accelerometer channel value.
in_accel_z_calibbias	Calibration offset for the Z-axis accelerometer channel.
in_accel_z_raw	Raw Z-axis accelerometer channel value.
3-Axis Gyro related device files	Description
in_anglvel_filter_low_pass_3db_frequency	Bandwidth for the gyroscope channels.
in_anglvel_scale	Scale for the gyroscope channels.
in_anglvel_x_calibbias	Calibration offset for the X-axis gyroscope channel.
in_anglvel_x_raw	Raw X-axis gyroscope channel value.
in_anglvel_y_calibbias	Calibration offset for the Y-axis gyroscope channel.
in_anglvel_y_raw	Raw Y-axis gyroscope channel value.
in_anglvel_z_calibbias	Calibration offset for the Z-axis gyroscope channel.
in_anglvel_z_raw	Raw Z-axis gyroscope channel value.
3-Axis Magnetometer related device files	Description
in_magn_filter_low_pass_3db_frequency	Bandwidth for the magnetometer channels.
in_magn_scale	Scale for the magnetometer channels.
in_magn_x_raw	Raw X-axis magnetometer channel value.
in_magn_y_raw	Raw Y-axis magnetometer channel value.
in_magn_z_raw	Raw Z-axis magnetometer channel value.
Barometric pressure sensor related files	Description
in_pressure_raw	Raw barometric pressure sensor channel value.
in_pressure_scale	Scale for the barometric pressure sensor channel.
Temperature sensor related files	Description
in_temp0_offset	Offset for temperature sensor channel.
in_temp0_raw	Raw temperature channel value.
in_temp0_scale	Scale for the temperature sensor channel.
Power supply monitor related files	Description
in_voltage0_supply_raw	Raw power supply monitor channel value.
in_voltage0_supply_scale	Scale for the power supply monitor channel.
Auxiliary ADC related files	Description
in_voltage1_raw	Raw auxiliary ADC channel value.
in_voltage1_scale	Scale for the auxiliary ADC channel.
Miscellaneous device files	Description
name	Name of the IIO device.
sampling_frequency	Currently selected sample rate.

Show device name

This specifies any shell prompt running on the target

root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat name
adis16400

Set sampling frequency

The sampling frequency of the device can be set by writing the desired value to the sampling_frequency file. The driver will automatically round up to the nearest supported sampling frequency.

Example:

This specifies any shell prompt running on the target

root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat sampling_frequency
819.202
root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> echo 546 > sampling_frequency
root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat sampling_frequency
546.135

Show channel value

A channel value can be read from its _raw attribute. The value returned by the _raw attribute is the raw value as reported by the device. To get the processed value of the channel in a standardized unit add the channels _offset attribute to the _raw value and multiply the result by _scale attribute. If no _offset attribute is present assume 0 for the offset.

processed value = (raw + offset) * scale

The units by the IIO framework are:

Acceleration: Meter per Second squared
Angular velocity: Rad per second
Pressure: kilo Pascal
Voltage: milli Volts
Temperature: milli-degree Celsius

Example:

This specifies any shell prompt running on the target

root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat in_accel_z_raw
1202
root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat in_accel_scale
0.008168

Z-axis acceleration = in_accel_z_raw * in_accel_scale = 1202 * 0.008168 m/s^2 = 9.81 m/s^2

Set channel bandwidth

The channels bandwidth can be set by writing the desired value to the channels _filter_low_pass_3db_frequency attribute. The driver will automatically round up to the nearest supported bandwidth.

Note that all channels share the same low pass filter frequency so changing it for one channel will change it for all other channels as well. Also note that the low pass filter frequency depends on the sampling frequency, so changing the sampling frequency will scale the low pass filter frequency accordingly. E.g. reducing the sampling frequency by a factor of two will also reduce the bandwidth by a factor of two.

Example:

This specifies any shell prompt running on the target

root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat in_anglvel_filter_low_pass_3db_frequency
409.600000
root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> echo 150 > in_anglvel_filter_low_pass_3db_frequency
root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat in_anglvel_filter_low_pass_3db_frequency
163.840400

Trigger management

This driver only supports it's own default trigger source adis16400-dev0

This specifies any shell prompt running on the target

root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0> cat trigger/current_trigger
adis16400-dev0

Buffer management

This specifies any shell prompt running on the target

root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0/buffer> ls
enable           length

The Industrial I/O subsystem provides support for various ring buffer based data acquisition methods. Apart from device specific hardware buffer support, the user can chose between two different software ring buffer implementations. One is the IIO lock free software ring, and the other is based on Linux kfifo. Devices with buffer support feature an additional sub-folder in the /sys/bus/iio/devices/deviceX/ folder hierarchy. Called deviceX:bufferY, where Y defaults to 0, for devices with a single buffer.

Every buffer implementation features a set of files:

length
Get/set the number of sample sets that may be held by the buffer.

enable
Enables/disables the buffer. This file should be written last, after length and selection of scan elements.

watermark
A single positive integer specifying the maximum number of scan elements to wait for. Poll will block until the watermark is reached. Blocking read will wait until the minimum between the requested read amount or the low water mark is available. Non-blocking read will retrieve the available samples from the buffer even if there are less samples then watermark level. This allows the application to block on poll with a timeout and read the available samples after the timeout expires and thus have a maximum delay guarantee.

data_available
A read-only value indicating the bytes of data available in the buffer. In the case of an output buffer, this indicates the amount of empty space available to write data to. In the case of an input buffer, this indicates the amount of data available for reading.

length_align_bytes
Using the high-speed interface. DMA buffers may have an alignment requirement for the buffer length. Newer versions of the kernel will report the alignment requirements associated with a device through the `length_align_bytes` property.

scan_elements
The scan_elements directory contains interfaces for elements that will be captured for a single triggered sample set in the buffer.

02 Mar 2011 15:16

This specifies any shell prompt running on the target

root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0/scan_elements>ls
in_accel_x_en             in_gyro_y_index           in_magn_z_type
in_accel_x_index          in_gyro_y_type            in_temp0_en
in_accel_x_type           in_gyro_z_en              in_temp0_index
in_accel_y_en             in_gyro_z_index           in_temp0_type
in_accel_y_index          in_gyro_z_type            in_timestamp_en
in_accel_y_type           in_magn_x_en              in_timestamp_index
in_accel_z_en             in_magn_x_index           in_timestamp_type
in_accel_z_index          in_magn_x_type            in_voltage0_supply_en
in_accel_z_type           in_magn_y_en              in_voltage0_supply_index
in_gyro_x_en              in_magn_y_index           in_voltage0_supply_type
in_gyro_x_index           in_magn_y_type            in_voltage1_en
in_gyro_x_type            in_magn_z_en              in_voltage1_index
in_gyro_y_en              in_magn_z_index           in_voltage1_type
root:/sys/devices/platform/bfin-spi.0/spi0.1/iio:device0/scan_elements>

in_voltageX_en / in_voltageX-voltageY_en / timestamp_en:
Scan element control for triggered data capture. Writing 1 will enable the scan element, writing 0 will disable it

in_voltageX_type / in_voltageX-voltageY_type / timestamp_type:
Description of the scan element data storage within the buffer and therefore in the form in which it is read from user-space. Form is [s|u]bits/storage-bits. s or u specifies if signed (2's complement) or unsigned. bits is the number of bits of data and storage-bits is the space (after padding) that it occupies in the buffer. Note that some devices will have additional information in the unused bits so to get a clean value, the bits value must be used to mask the buffer output value appropriately. The storage-bits value also specifies the data alignment. So u12/16 will be a unsigned 12 bit integer stored in a 16 bit location aligned to a 16 bit boundary. For other storage combinations this attribute will be extended appropriately.

in_voltageX_index / in_voltageX-voltageY_index / timestamp_index:
A single positive integer specifying the position of this scan element in the buffer. Note these are not dependent on what is enabled and may not be contiguous. Thus for user-space to establish the full layout these must be used in conjunction with all _en attributes to establish which channels are present, and the relevant _type attributes to establish the data storage format.

02 Mar 2011 15:16