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ADXL367 No-OS Driver

Supported Devices

ADXL367

Overview

The ADXL367 is an ultralow power, 3-axis microelectromechanical systems (MEMS) accelerometer that consumes only 0.89 μA at a 100 Hz output data rate and 180 nA when in motion-triggered wake-up mode. Unlike accelerometers that use power duty cycling to achieve low power consumption, the ADXL367 does not alias input signals by undersampling, but samples the full bandwidth of the sensor at all data rates.

The ADXL367 always provides 14-bit output resolution. 8-bit formatted data is offered for more efficient single-byte transfers when a lower resolution is sufficient. 12-bit formatted data is also provided for ADXL362 design compatibility. Measurement ranges of ±2 g, ±4g, and ±8 g are available, with a resolution of 0.25 mg/LSB on the ±2 g range.

In addition to its ultralow power consumption, the ADXL367 has many features to enable true system level power reduction. It includes a deep multimode output first in, first out (FIFO), a built-in micropower temperature sensor, an internal analog-to-digital converter (ADC) for synchronous conversion of an additional analog input with interrupt capability, single-tap and double-tap detection that can operate at any output data rate with only an added 35nA of current, and a state machine to prevent a false triggering. In addition, the ADXL367 has provisions for external control of the sampling time and/or an external clock.

The ADXL367 operates on a wide 1.1 V to 3.6 V supply range, and can interface, if necessary, to a host operating on a separate supply voltage. It is available in a 2.2 mm × 2.3 mm × 0.87mm package.

Applications

24/7 sensing
Hearing aids
Vital signs monitoring devices
Motion-enabled power save switches
Motion-enabled metering devices
Smart watch with single-cell operation
Smart home

ADI No-OS

The goal of ADI Microcontroller No-OS is to be able to provide reference projects for lower end processors, which can't run Linux, or aren't running a specific operating system, to help those customers using microcontrollers with ADI parts. ADI No-OS offers generic drivers which can be used as a base for any microcontroller platform and also example projects which are using these drivers on various microcontroller platforms.

For more information about ADI No-OS and supported microcontroller platforms see: ADI No-OS

ADXL367 ADI No-OS driver

ADXL367 Driver Source Code

The source code for ADXL367 driver can be found here:

The driver also uses the ADI util, delay and print_log libraries, so make sure you also add the necessary files in your project. The source code for the libraries can be found here:

In order to be able to use this driver you will have to provide the specific implementation for the communication APIs and the specific types they use. If the SPI communication is chosen, there are three functions which are called by the ADXL367 driver and have to be implemented:

no_os_spi_init() – initializes the communication peripheral.
no_os_spi_write_and_read() – writes and reads data to/from the device.
no_os_spi_remove() – deinitializes the communication peripheral.

And there are two data types that have to be defined:

no_os_spi_desc - structure holding the SPI descriptor
no_os_spi_init_param - structure holding the parameters for SPI initialization

If the I2C communication is chosen, there are four functions which are called by the ADXL367 driver:

i2c_init() – initializes the communication peripheral.
i2c_write() – writes data to the device.
i2c_read() – reads data from the device.
i2c_remove() – deinitializes the communication peripheral.

And there are two data types that have to be defined:

no_os_i2c_desc - structure holding the I2C descriptor
no_os_i2c_init_param - structure holding the parameters for I2C initialization

An example of a header file containing the prototypes of the functions which have to be implemented, along with some generic data types they are using can be found below:

ADXL367 Code Driver Documentation

Source code documentation for the driver is automatically generated using the Doxygen tool and it is available below:

ADXL367 Device Configuration

Driver Initialization

In order to be able to use the device, you will have to provide the support for the communication protocol (SPI or I2C) as mentioned above. The first API to be called is adxl367_init. Make sure that it returns 0, which means that the driver was initialized correctly.

Range Configuration

By default, the device uses +/- 2g range configuration. You may modify this value to +/- 4g or +/- 8g by using adxl367_set_range API.

Axis Calibration Configuration

You may set an offset for each axis for calibration purposes by using adxl367_set_offset. The offset is disabled by default. The data provided in adxl367_set_offset will be in two's complement format. The offset is added after all other signal processing is taking place.

FIFO Configuration

There are 513 locations in the FIFO. Each location contains an acceleration data point on an axis. In case you want to use the FIFO, you are able to modify the number of FIFO samples to be stored in the FIFO. The default and maximum value is 513, but can be modified using adxl367_set_fifo_sample_sets_nb API. A full set-up for FIFO can be done using adxl367_fifo_setup API.

Activity Detection Configuration

In case you want to use the activity detection algorithm, you can enable this feature on any axis using adxl367_setup_activity_detection API. By default the activity detection feature is disabled. You will have to specify a threshold for the activity detection and a number of consecutive measurements above the threshold which would trigger the detection of an activity.

Inactivity Detection Configuration

In case you want to use the inactivity detection algorithm, you can enable this feature on any axis using adxl367_setup_inactivity_detection API. By default the activity detection feature is disabled. You will have to specify a threshold for the inactivity detection and a number of consecutive measurements below the threshold which would trigger the detection of an inactivity.

Interrupts Configuration

The device allows the usage of interrupts which can be mapped to INT1 or INT2 pins. In case you want to use interrupts, make sure you configure the interrupt map by using adxl367_int_map API.

The following events can be mapped to the interrupt pins:

DATA READY interrupt - it is triggered when new acceleration data is available to the interface and it is cleared on a read of data register, using adxl367_read_raw_temp API.
FIFO WATERMARK interrupt - it is triggered when the entries in the FIFO are equal to the setting made when calling adxl367_set_fifo_sample_sets_nb API. It is cleared when the number of entries in the FIFO is less than the number of samples set by adxl367_set_fifo_sample_sets_nb API.
FIFO OVERRUN interrupt - it is triggered when the FIFO is so far overrange that data is lost. The specified side of the FIFO is 513 locations. The interrupt is triggered only when there is an attempt to write past this 513-location limit.
FIFO READY interrupt - it is set if there is at least one sample available in the FIFO output buffer.
ACTIVITY interrupt - it is set when the measured acceleration on any axis is above the set threshold, using adxl367_setup_activity_detection API. A read of the status register clears the interrupt, but this interrupt is triggered again at the end of the next measurement if the activity conditions are still satisfied.
INACTIVITY interrupt - it is set when the measured acceleration on any axis is below the set threshold, using adxl367_setup_inactivity_detection API. A read of the status register clears the interrupt, but this interrupt is triggered again at the end of the next measurement if the inactivity conditions are still satisfied.
AWAKE interrupt - it is set if the accelerometer is in an active state (AWAKE = 1)

ADXL367 Device Measurements

Operation Mode Setting

After the specific configuration was performed as mentioned above, you can set the device in the desired measurement mode, using adxl367_set_power_mode API. The available operation modes for measurement are as follows:

ADXL367_OP_MEASURE - measurement mode
ADXL367_OP_STANDBY - stand-by mode, mode in which the configuration of the device should be done

Temperature Data

By using adxl367_temp_read_en, temperature data can be enabled. Data can be obtained by calling adxl367_read_temperature API. The temperature is Celsius degrees, with scaling already applied.

If you want to obtain the raw temperature data without any scaling applies, simply call adxl367_read_raw_temp API.

Acceleration Data

Single Data Set

If you want to obtain a single data set, you may use adxl367_get_g_xyz API to obtain the data converted to g, or adxl367_get_raw_xyz API to obtain the raw data. The raw data is in two's complement format and it does not have the scaling applied.

FIFO Data

If you want to read from the FIFO, you may use adxl367_read_converted_fifo API to obtain the data converted to g and Celsius degrees for temperature, or adxl367_read_raw_fifo api to obtain the raw data. The raw data is in two's complement format and it does not have the scaling applied. The parameter entries shows the number of valid measurements in the FIFO which were read.

ADXL367 Driver Initialization Example

SPI Communication Example

// Particular SPI configuration
struct no_os_spi_init_param spi_ip = {
	.device_id = SPI_DEVICE_ID,
	.max_speed_hz = 100000,
	.mode = NO_OS_SPI_MODE_0,
	.chip_select = 0U,
	.bit_order = NO_OS_SPI_BIT_ORDER_MSB_FIRST,
	.platform_ops = SPI_OPS,
	.extra = &spi_extra
};

struct adxl367_init_param init_param = {
	.spi_init = spi_ip,
	.comm_type = ADXL367_SPI_COMM
};
// Device descriptor
struct adxl367_dev *dev;

adxl367_init(&dev, init_param);

adxl367_self_test(dev);

adxl367_temp_read_en(dev, 1);

adxl367_set_output_rate(dev, ADXL367_ODR_200HZ);

adxl367_fifo_setup(dev, ADXL367_OLDEST_SAVED, ADXL367_FIFO_FORMAT_XYZT, 50);

//be sure to make all configs before switching to measure mode
adxl367_set_power_mode(dev, ADXL367_OP_MEASURE);

uint16_t entries;
struct adxl367_fractional_val x[128], y[128], z[128], temp[128];

adxl367_read_converted_fifo(dev, x, y, z, temp, &entries);

pr_info("Number of read entries from the FIFO %d \n", entries);

for (uint8_t i = 0; i < entries / 4; i ++) {
	pr_info("x=%d"".%09u m/s^2\n", (int)x[i].integer, (abs)(x[i].fractional));
	pr_info("y=%d"".%09u m/s^2\n", (int)y[i].integer, (abs)(y[i].fractional));
	pr_info("z=%d"".%09u m/s^2\n", (int)z[i].integer, (abs)(z[i].fractional));
	pr_info("temp=%d"".%09u C\n", (int)temp[i].integer, (abs)(temp[i].fractional));
	pr_info("\n");
}

ADI IIO No-OS

ADXL367 IIO No-OS driver

The ADXL367 IIO driver comes on top of ADXL367 driver and offers support for interfacing IIO clients through IIO lib.

ADXL367 IIO Device Configuration

Device Attributes

ADXL367 IIO device does not have any device specific attributes.

Device Channels

ADXL367 IIO device has 0 input channels and 4 output channels: 3 acceleration channels and 1 temperature channel.

Acceleration channels

The acceleration channels are:

Channel 0: X axis
Channel 1: Y axis
Channel 2: Z axis

Each acceleration channel has 6 attributes. 4 of these attributes are shared in value with the other acceleration channels and 2 of these attributes can have different values for each channel.

The attributes are:

calibbias - offset added to the axis after all other signal processing. The calibbias value will be applied as an offset to the raw value bits.
raw - is the raw acceleration value read from the device.
sampling_frequency (shared) - is the sampling frequency for acceleration data. This value is common for all three acceleration channels and for temperature, too.
sampling_frequency_available (shared) - is the list of available sampling frequency values. This list is common for all three acceleration channels.
scale (shared) - is the scale that has to be applied to the raw value in order to obtain the converted real value in m/s^2.
scale_available (shared) - lists the available scale options (in this way device's range can be modified)

converted_accel [m/s^2] = (raw + calibbias) * scale

Temperature channel

The temperature channel is:

Channel 4: temp

The channel has 3 attributes, as follows:

offset - is the offset that has to be applied to the raw value in order to obtain the converted real value in degrees Celsius.
raw - is the raw temperature value read from the device.
scale - is the scale that has to be applied to the raw value in order to obtain the converted real value in degrees Celsius.

converted_temp [degrees Celsius] = (raw + offset) * scale

Device buffers

The ADXL367 IIO devices driver supports the usage of a data buffer for reading purposes.

ADXL367 IIO Driver Initialization Example

#define DATA_BUFFER_SIZE 400
uint8_t iio_data_buffer[DATA_BUFFER_SIZE*4*sizeof(int16_t)];

struct adxl367_iio_dev *adxl367_iio_desc;
struct adxl367_iio_init_param adxl367_init_par;

// Particular SPI configuration
struct no_os_spi_init_param spi_ip = {
	.device_id = SPI_DEVICE_ID,
	.max_speed_hz = 100000,
	.mode = NO_OS_SPI_MODE_0,
	.chip_select = 0U,
	.bit_order = NO_OS_SPI_BIT_ORDER_MSB_FIRST,
	.platform_ops = SPI_OPS,
	.extra = &spi_extra
};

struct adxl367_init_param init_param = {
	.spi_init = spi_ip,
	.comm_type = ADXL367_SPI_COMM
};

struct iio_data_buffer accel_buff = {
	.buff = (void *)iio_data_buffer,
	.size = DATA_BUFFER_SIZE*4*sizeof(int16_t)
};

adxl367_iio_ip.adxl367_initial_param = &init_param;
adxl367_iio_init(&adxl367_iio_desc, &adxl367_iio_ip);

struct iio_app_device iio_devices[] = {
	{
		.name = "adxl367",
		.dev = adxl367_iio_desc,
		.dev_descriptor = adxl367_iio_desc->iio_dev,
		.read_buff = &accel_buff,
	}
};

return iio_app_run(iio_devices, NO_OS_ARRAY_SIZE(iio_devices));

Wiki

Analog Devices Wiki

Table of Contents

ADXL367 No-OS Driver

Supported Devices

Overview

Applications

ADI No-OS

ADXL367 ADI No-OS driver

ADXL367 Driver Source Code

ADXL367 Code Driver Documentation

ADXL367 Device Configuration

Driver Initialization

Range Configuration

Axis Calibration Configuration

FIFO Configuration

Activity Detection Configuration

Inactivity Detection Configuration

Interrupts Configuration

ADXL367 Device Measurements

Operation Mode Setting

Temperature Data

Acceleration Data

Single Data Set

FIFO Data

ADXL367 Driver Initialization Example

SPI Communication Example

ADI IIO No-OS

ADXL367 IIO No-OS driver

ADXL367 IIO Device Configuration

Device Attributes

Device Channels

Acceleration channels

Temperature channel

Device buffers

ADXL367 IIO Driver Initialization Example

Analog Devices Wiki

Table of Contents

ADXL367 No-OS Driver

Supported Devices

Overview

Applications

ADI No-OS

ADXL367 ADI No-OS driver

ADXL367 Driver Source Code

ADXL367 Code Driver Documentation

ADXL367 Device Configuration

Driver Initialization

Range Configuration

Axis Calibration Configuration

FIFO Configuration

Activity Detection Configuration

Inactivity Detection Configuration

Interrupts Configuration

ADXL367 Device Measurements

Operation Mode Setting

Temperature Data

Acceleration Data

Single Data Set

FIFO Data

ADXL367 Driver Initialization Example

SPI Communication Example

ADI IIO No-OS

ADXL367 IIO No-OS driver

ADXL367 IIO Device Configuration

Device Attributes

Device Channels

Acceleration channels

Temperature channel

Device buffers

ADXL367 IIO Driver Initialization Example

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