Wiki

Below is the source of this page. To edit this source as well as other pages on the wiki, you must login.
====== ADXL367 Input 3-Axis Digital Accelerometer Linux Driver ======

  * [[adi>ADXL367|Product Page]]

===== Supported Devices =====

  * [[adi>ADXL367]]

===== Evaluation Boards =====

  * [[adi>EVAL-ADXL367Z]] 
  * [[adi>EVAL-ADXL367-SDP]] 

====== Source Code ======

===== Status =====

^ Source ^ Mainlined? ^
| [[git.linux.org>drivers/iio/accel/adxl367.c|git]] | [[git.linux.org>drivers/iio/accel/adxl367.c|Yes]]  |

===== Files =====

^ Function ^ File ^
| core driver | [[linux.github>master?drivers/iio/accel/adxl367.c | drivers/iio/accel/adxl367.c]] |
| spi driver | [[linux.github>master?drivers/iio/accel/adxl367_spi.c | drivers/iio/accel/adxl367_spi.c]] |
| i2c driver | [[linux.github>master?drivers/iio/accel/adxl367_i2c.c | drivers/iio/accel/adxl367_i2c.c]] |
| header | [[linux.github>master?drivers/iio/iio/accel/adxl367.h | drivers/iio/accel/adxl367.h]] |
| Documentation | [[linux.github>master?./Documentation/devicetree/bindings/iio/accel/adi,adxl367.yaml | adi,adxl367.yaml]] |

Example device tree

^ Function ^ File ^
| dts  | [[linux.github>rpi-4.19.y?arch/arm/boot/dts/overlays/rpi-adxl367-overlay.dts | rpi-adxl367-overlay.dts]] |

====== Example platform device initialization ======

Required devicetree properties:
  * compatible: Needs to be the name of the device. E.g. "adi,adxl367"
  * reg: the I2C address or SPI chip select number for the device

Required properties for SPI bus usage:
  * spi-max-frequency: Maximum SPI clock frequency.

Optional properties:
  * interrupts: a list of interrupt specifiers

Example for a SPI device node:
<code>
	#address-cells = <1>;
	#size-cells = <0>;
	status = "okay";

	adxl367@0 {
		compatible = "adi,adxl367";
		reg = <0>;
		spi-max-frequency = <1000000>;
		interrupt-parent = <&gpio>;
		interrupts = <25 IRQ_TYPE_EDGE_RISING>;
	};
</code>

Example for a I2C device node:
<code>
	#address-cells = <1>;
	#size-cells = <0>;
	status = "okay";

	adxl367@53 {
		compatible = "adi,adxl367";
		reg = <53>;
		interrupt-parent = <&gpio>;
		interrupts = <25 IRQ_TYPE_EDGE_RISING>;
	};
</code>

====== Driver testing ======

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/> **cd /sys/bus/iio/devices/**
root:/sys/bus/iio/devices> ls
iio:device0

root:/sys/bus/iio/devices> **cd iio\:device0**

root:/sys/bus/iio/devices/iio:device0> **ls -l**
drwxr-xr-x 2 root root    0 May  3 16:17 buffer
-r--r--r-- 1 root root 4096 May  3 16:17 dev
drwxr-xr-x 2 root root    0 May  3 16:17 events
-rw-r--r-- 1 root root 4096 May  3 16:17 in_accel_scale
-r--r--r-- 1 root root 4096 May  3 16:17 in_accel_scale_available
-rw-r--r-- 1 root root 4096 May  3 16:17 in_accel_x_raw
-rw-r--r-- 1 root root 4096 May  3 16:17 in_accel_y_raw
-rw-r--r-- 1 root root 4096 May  3 16:17 in_accel_z_raw
-rw-r--r-- 1 root root 4096 May  3 16:17 in_temp_offset
-rw-r--r-- 1 root root 4096 May  3 16:17 in_temp_raw
-rw-r--r-- 1 root root 4096 May  3 16:17 in_temp_scale
-rw-r--r-- 1 root root 4096 May  3 16:17 in_voltage_offset
-rw-r--r-- 1 root root 4096 May  3 16:17 in_voltage_raw
-rw-r--r-- 1 root root 4096 May  3 16:17 in_voltage_scale
-r--r--r-- 1 root root 4096 May  3 16:17 name
lrwxrwxrwx 1 root root    0 May  3 16:17 of_node -> ../../../../../../../../firmware/devicetree/base/soc/spi@7e204000/adxl367@0
drwxr-xr-x 2 root root    0 May  3 16:17 power
-rw-r--r-- 1 root root 4096 May  3 16:17 sampling_frequency
-r--r--r-- 1 root root 4096 May  3 16:17 sampling_frequency_available
drwxr-xr-x 2 root root    0 May  3 16:17 scan_elements
lrwxrwxrwx 1 root root    0 May  3 16:17 subsystem -> ../../../../../../../../bus/iio
-rw-r--r-- 1 root root 4096 May  3 16:17 uevent
</xterm></WRAP>

=== Show device name ===

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/bus/iio/devices/iio:device0> **cat name**
adxl367
</xterm></WRAP>

=== Show scale ===

**Description:**\\
scale to be applied to in_accel_*_raw in order to obtain the acceleration.

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/bus/iio/devices/iio:device0> **cat in_accel_scale**
0.002394347
</xterm></WRAP>

=== Show axis x measurement ===

**Description:**\\
Raw unscaled acceleration measurement on x axis

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/bus/iio/devices/iio:device0> **cat in_accel_x_raw**
-5
</xterm></WRAP>

=== Set sampling frequency ===

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/bus/iio/devices/iio:device0> **cat sampling_frequency_available**
12.500000 25.000000 50.000000 100.000000 200.000000 400.000000
root:/sys/bus/iio/devices/iio:device0> **cat sampling_frequency**
12.500000
root:/sys/bus/iio/devices/iio:device0> **echo 400.000000 > sampling_frequency**
root:/sys/bus/iio/devices/iio:device0> **cat sampling_frequency**
400.000000
</xterm></WRAP>

===== Using the FIFO Buffer =====

**Description:**\\
The ADXL367 includes a deep, 512 sample FIFO buffer. The 512 FIFO samples can be allotted in several ways, such as the following:
  * 512 sample sets of single-axis data
  * 256 sample sets of concurrent 2-channel data
  * 170 sample sets of concurrent 3-channel data
  * 128 sample sets of concurrent 4-channel data

==== Buffer management ====

**Description:**\\
The scan_elements directory contains interfaces for elements that will be captured for a single triggered sample set in the buffer

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/bus/iio/devices/iio:device0> **cd scan_elements/**
root:/sys/bus/iio/devices/iio:device0/scan_elements> **ls -l**
-rw-r--r-- 1 root root 4096 May  3 16:17 in_accel_x_en
-r--r--r-- 1 root root 4096 May  3 16:17 in_accel_x_index
-r--r--r-- 1 root root 4096 May  3 16:17 in_accel_x_type
-rw-r--r-- 1 root root 4096 May  3 16:17 in_accel_y_en
-r--r--r-- 1 root root 4096 May  3 16:17 in_accel_y_index
-r--r--r-- 1 root root 4096 May  3 16:17 in_accel_y_type
-rw-r--r-- 1 root root 4096 May  3 16:17 in_accel_z_en
-r--r--r-- 1 root root 4096 May  3 16:17 in_accel_z_index
-r--r--r-- 1 root root 4096 May  3 16:17 in_accel_z_type
-rw-r--r-- 1 root root 4096 May  3 16:17 in_temp_en
-r--r--r-- 1 root root 4096 May  3 16:17 in_temp_index
-r--r--r-- 1 root root 4096 May  3 16:17 in_temp_type
-rw-r--r-- 1 root root 4096 May  3 16:17 in_voltage_en
-r--r--r-- 1 root root 4096 May  3 16:17 in_voltage_index
-r--r--r-- 1 root root 4096 May  3 16:17 in_voltage_type
</xterm></WRAP>

Before enabling the buffer, a few steps need to be completed. 
  * For example, if we want the FIFO to store sample sets of concurrent 3-channel data, we need to enable the scan elements:
<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/bus/iio/devices/iio:device0/scan_elements> **echo 1 > in_accel_x_en**
root:/sys/bus/iio/devices/iio:device0/scan_elements> **echo 1 > in_accel_y_en**
root:/sys/bus/iio/devices/iio:device0/scan_elements> **echo 1 > in_accel_z_en**
</xterm></WRAP>

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/bus/iio/devices/iio:device0/scan_elements> **cd ../buffer/**
root:/sys/bus/iio/devices/iio:device0/buffer> ls -l
-r--r--r-- 1 root root 4096 May  3 16:17 data_available
-rw-r--r-- 1 root root 4096 May  3 16:17 enable
-r--r--r-- 1 root root 4096 May  3 16:17 hwfifo_enabled
-r--r--r-- 1 root root 4096 May  3 16:17 hwfifo_watermark
-r--r--r-- 1 root root 4096 May  3 16:17 hwfifo_watermark_max
-r--r--r-- 1 root root 4096 May  3 16:17 hwfifo_watermark_min
-rw-r--r-- 1 root root 4096 May  3 16:17 length
-rw-r--r-- 1 root root 4096 May  3 16:17 watermark
</xterm></WRAP>

  * Set the buffer length:
<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/bus/iio/devices/iio:device0/buffer> **echo 1024 > length**
</xterm></WRAP>

  * Set the watermak:
<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/bus/iio/devices/iio:device0/buffer> **echo 512 > watermark**
</xterm></WRAP>

  * Enable the buffer:
<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/bus/iio/devices/iio:device0/buffer> **echo 1 > enable**
</xterm></WRAP>

  * Read the samples:
<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/bus/iio/devices/iio:device0/buffer> **cat /dev/iio:device0**
</xterm></WRAP>

====== Low level register access via debugfs (direct_reg_access) ======

Some IIO drivers feature an optional debug facility, allowing users to read or write registers directly. Special care needs to be taken when using this feature, since you can modify registers on the back of the driver. Accessing debugfs requires root privileges.

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/> **/sys/kernel/debug/iio/iio:device0/**
root:/sys/kernel/debug/iio/iio:device0> ls direct_reg_access  
direct_reg_access
</xterm></WRAP>

Reading

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root:/sys/kernel/debug/iio/iio:device0> echo 0x0 > direct_reg_access
root:/sys/kernel/debug/iio/iio:device0> cat direct_reg_access 
0xAD
</xterm></WRAP>

Writing

Write ADDRESS VALUE

<WRAP box bggreen><wrap info>This specifies any shell prompt running on the target</wrap>
<xterm>
root@analog:/sys/kernel/debug/iio/iio:device0> echo 0x3D 0x80 > direct_reg_access   
root@analog:/sys/kernel/debug/iio/iio:device0> cat direct_reg_access 
0x80
</xterm></WRAP>

====== More Information ======

{{page>software:linux:docs:iio:iio_snippets#iio pointers&noheader&firstseconly&noeditbtn}}
Analog Devices Wiki

Page Tools
