• ADXL362

• CN0274

• EVAL-ADXL362Z
• EVAL-ADXL362Z-DB
• EVAL-ADXL362Z-MLP
• EVAL-ADXL362Z-S

• Product Page

Digital Accelerometer characteristics are application specific and may vary between boards and models. The platform_data for the device's “struct device” holds this information.

enum adxl_odr {
	ADXL_ODR_12_5HZ	= 13,
	ADXL_ODR_25HZ	= 25,
	ADXL_ODR_50HZ	= 50,
	ADXL_ODR_100HZ	= 100,
	ADXL_ODR_200HZ	= 200,
	ADXL_ODR_400HZ	= 400,
};
 
enum adxl_g_range {
	ADXL_RANGE_PM_2g = 2,
	ADXL_RANGE_PM_4g = 4,
	ADXL_RANGE_PM_8g = 8,
};
 
enum adxl_power_mode {
	ADXL_NORM_OPERATION	= 0,
	ADXL_LOW_NOISE_MODE	= 1,
	ADXL_ULTRA_LOW_NOISE_MODE = 2,
};
 
struct adxl362_platform_data {
	/*
	 * data_range:
	 * Measurement range selection +/- 2,4,8 g
	 */
	enum adxl_g_range data_range;
 
	/*
	 * low_power_mode:
	 * Power versus noise tradeoff.
	 */
	enum adxl_power_mode low_power_mode;
 
	/*
	 * data_rate:
	 * Selects the output data rate (ODR).
	 */
	enum adxl_odr data_rate;
 
	/*
	 * half_bw:
	 * Sets the anti-aliasing filter to 1/4 of the output data rate (ODR)
	 */
	bool half_bw;
 
	/*
	 * watermark_odr:
	 * The Watermark feature can be used to reduce the interrupt/poll load
	 * of the system. The FIFO fills up to watermark value in sample sets
	 * [1..170] and then generates an interrupt. Each ODR can have it's
	 * own watermark.
	 */
	u8 watermark_odr_12Hz;
	u8 watermark_odr_25Hz;
	u8 watermark_odr_50Hz;
	u8 watermark_odr_100Hz;
	u8 watermark_odr_200Hz;
	u8 watermark_odr_400Hz;
 
	/*
	 * When acceleration measurements are received from the ADXL362
	 * events are sent to the input event subsystem. The following settings
	 * select the event code for ABS x, y and z axis data
	 * respectively. The event codes can also be negated to further account
	 * for sensor orientation.
	 */
	s32 ev_code_x;	/* (+/-)ABS_X,Y,Z */
	s32 ev_code_y;	/* (+/-)ABS_X,Y,Z */
	s32 ev_code_z;	/* (+/-)ABS_X,Y,Z */
	s32 abs_fuzz;	/* input fuzz val */
 
	/*
	 * [in]activity_threshold:
	 * holds the threshold value for activity detection.
	 * The data format is unsigned. The scale factor is
	 * 1mg/LSB.
	 */
	u16 activity_threshold;
	u16 inactivity_threshold;
 
	/*
	 * [in]activity_time:
	 * is an unsigned time value representing the
	 * amount of time that acceleration must be [below]/above the value in
	 * [in]activity_threshold for [in]activity to be declared.
	 * The scale factor is 1ms/LSB.
	 */
	u32 inactivity_time;
	u32 activity_time;
 
	/*
	 * referenced_[in]activity_en:
	 * Sets [in]activity detection to operate in referenced mode opposed to
	 * absolute mode.
	 */
	bool referenced_activity_en;
	bool referenced_inactivity_en;
 
	/*
	 * Use ADXL362 INT2 pin instead of INT1 pin for interrupt output
	 */
	bool use_int2;
 
	/*
	 * Optional IRQ flags
	 */
	unsigned irqflags;
};

static struct adxl362_platform_data adxl362_info = {
	.data_rate = ADXL_ODR_100HZ,	/* 100Hz */
	.data_range = ADXL_RANGE_PM_2g,	/* +/- 2000mg */
	.activity_threshold = 70,	/* 70mg (referenced) */
	.inactivity_threshold = 30,	/* 30mg (referenced) */
	.inactivity_time = 10000,	/* 10s */
	.activity_time = 1,		/* 1ms */
	.referenced_activity_en = true, /* cancel static accel. of gravity */
	.referenced_inactivity_en = true, /* cancel static accel. of gravity */
	.watermark_odr_12Hz = 1,
	.watermark_odr_25Hz = 1,
	.watermark_odr_50Hz = 1,
	.watermark_odr_100Hz = 1,
	.watermark_odr_200Hz = 2, /* limit irq/poll interval to 10ms */
	.watermark_odr_400Hz = 4, /* limit irq/poll interval to 10ms */
	.ev_code_x = ABS_X,		/* default mapping */
	.ev_code_y = ABS_Y,
	.ev_code_z = ABS_Z,
};

Depending on the DDS 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_INPUT_ADXL362) || defined(CONFIG_INPUT_ADXL362_MODULE)
	{
		.modalias	= "adxl362",
		.platform_data	= &adxl362_info,
		.irq		= IRQ_PF6,
		.max_speed_hz	= 5000000,    /* max spi clock (SCK) speed in HZ */
		.bus_num	= 0,
		.chip_select 	= 1,
		.mode 		= SPI_MODE_0,
	},
#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);

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

Input device support
  -*- Generic input layer (needed for keyboard, mouse, ...)
  < >   Support for memoryless force-feedback devices
  < >   Polled input device skeleton
  < >   Sparse keymap support library
        * Userland interfaces *
  < >   Mouse interface
  < >   Joystick interface
  <*>   Event interface
  < >   Event debugging
        * Input Device Drivers *
  [ ]   Keyboards  --->
  [ ]   Mice  --->
  [ ]   Joysticks/Gamepads  --->
  [ ]   Tablets  --->
  [ ]   Touchscreens  --->
  [*]   Miscellaneous devices  --->
		--- Miscellaneous devices
		< >   Analog Devices AD714x Capacitance Touch Sensor
		< >   BMA150/SMB380 acceleration sensor support
		< >   MMA8450 - Freescale's 3-Axis, 8/12-bit Digital Accelerometer
		< >   MPU3050 Triaxial gyroscope sensor
		< >   Sharp GP2AP002A00F I2C Proximity/Opto sensor driver
		< >   Polled GPIO tilt switch
		< >   Kionix KXTJ9 tri-axis digital accelerometer
		< >   User level driver support
		< >   PCF8574 Keypad input device
		< >   Rotary encoders connected to GPIO pins
		< >   Analog Devices ADXL34x Three-Axis Digital Accelerometer
		<*>   Analog Devices ADXL362 Three-Axis Digital Accelerometer
		< >   VTI CMA3000 Tri-axis accelerometer
        Hardware I/O ports  --->

root:~> modprobe evdev
root:~> modprobe adxl362
input: ADXL362 accelerometer as /devices/platform/bfin-spi.0/spi_master/spi0/spi0.1/input/input0

Your kernel startup messages should include something like this

input: ADXL362 accelerometer as /devices/platform/bfin-spi.0/spi_master/spi0/spi0.1/input/input0

In case you see a message like this

adxl362 spi0.1: Failed to probe (0x00:0x00)

This means that the SPI communication and initilaization with the ADXL362 failed. check bus_num and chip_select in your platform device file

After the kernel boot your device folder should include at least one device node for the accelerometer

root:/> ls -al /dev/input/
drw-r--r--    2 root     root            0 Jan  1 00:03 .
drwxr-xr-x    5 root     root            0 Jan  1 00:03 ..
crw-rw-r--    1 root     root      13,  64 Jan  1 00:03 event0
root:/>

root:~> cat /sys/class/input/input0/name
ADXL362 accelerometer

root:/> event_test /dev/input/event0
Input driver version is 1.0.1
Input device ID: bus 0x1c vendor 0xad product 0xf2 version 0x1
Input device name: "ADXL362 accelerometer"
Supported events:
  Event type 0 (Sync)
  Event type 3 (Absolute)
    Event code 0 (X)
      Value   -144
      Min    -2000
      Max     2000
    Event code 1 (Y)
      Value   -256
      Min    -2000
      Max     2000
    Event code 2 (Z)
      Value    398
      Min    -2000
      Max     2000
Testing ... (interrupt to exit)
Event: time 43.641571, -------------- Report Sync ------------
Event: time 43.641582, type 3 (Absolute), code 0 (X), value 192
Event: time 43.641588, type 3 (Absolute), code 1 (Y), value 7
Event: time 43.641593, type 3 (Absolute), code 2 (Z), value 291
Event: time 43.641597, -------------- Report Sync ------------
Event: time 43.656442, type 3 (Absolute), code 0 (X), value 211
Event: time 43.656451, type 3 (Absolute), code 1 (Y), value 12
Event: time 43.656456, type 3 (Absolute), code 2 (Z), value 295
Event: time 43.656461, -------------- Report Sync ------------
Event: time 43.656476, type 3 (Absolute), code 1 (Y), value 15
Event: time 43.656481, type 3 (Absolute), code 2 (Z), value 280
Event: time 43.656486, -------------- Report Sync ------------

root:/> cd sys/class/input/input0/device/
root:/sys/devices/platform/bfin-spi.0/spi_master/spi0/spi0.1> ls -al
drwxr-xr-x    4 root     root             0 Jan  1 01:40 .
drwxr-xr-x    4 root     root             0 Jan  1 01:40 ..
-rw-rw-r--    1 root     root          4096 Jan  1 01:50 autosleep
lrwxrwxrwx    1 root     root             0 Jan  1 01:50 driver -> ../../../../../../bus/spi/drivers/adxl362
drwxr-xr-x    3 root     root             0 Jan  1 01:40 input
-r--r--r--    1 root     root          4096 Jan  1 01:50 modalias
drwxr-xr-x    2 root     root             0 Jan  1 01:50 power
-rw-rw-r--    1 root     root          4096 Jan  1 01:50 rate
lrwxrwxrwx    1 root     root             0 Jan  1 01:50 subsystem -> ../../../../../../bus/spi
-rw-r--r--    1 root     root          4096 Jan  1 01:50 uevent

Writing 'Output Data Rate' into rate sets the desired sample rate
Reading rate returns the current Output Data Rate

See table above for supported sample rates

root:/sys/devices/platform/bfin-spi.0/spi_master/spi0/spi0.1> echo 400 > rate
root:/sys/devices/platform/bfin-spi.0/spi_master/spi0/spi0.1> cat rate
400

Writing '1' into autosleep - enables Autosleep Upon Inactivity
Writing '0' into autosleep - disables Autosleep Upon Inactivity

root:/sys/devices/platform/bfin-spi.0/spi_master/spi0/spi0.1> echo 1 > autosleep
root:/sys/devices/platform/bfin-spi.0/spi_master/spi0/spi0.1> echo 0 > autosleep

Using this driver under Android as Acceleration Sensor Follow the link here ADXL362 Android Sensor