AD7768

AD7768 IIO Precision ADC Linux Driver.

Supported Devices

This driver supports the

Evaluation Boards

Description

This is a Linux industrial I/O (Linux Industrial I/O Subsystem) subsystem driver, targeting single channel serial interface ADCs. 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 Linux Industrial I/O Subsystem for more information.

Source Code

Status

Source

Mainlined?

git

[In progress…]

Files

Function

File

driver

drivers/iio/adc/ad7768.c

devicetree bindings

Documentation/devicetree/bindings/iio/adc/adi,ad7768.yaml

hdl project

hdl

Example Linux Device-Tree Initialization

Required properties:

  • compatible: Must be one of adi,ad7768, adi,ad7768-4.

  • reg: SPI chip select number for the device.

  • clocks: phandle to master clock of the device.

  • clock-names: Must be mclk.

  • spi-max-frequency: See Documentation/devicetree/bindings/spi/spi-bus.txt.

  • dmas: DMA specifier, consisting of a phandle to DMA controller node.

  • dma-names: Must be rx.

  • vref-supply: phandle to the regulator for ADC reference voltage.

Optional properties:

  • reset-gpios: Reset GPIO.

  • adi,data-lines: Number of DOUTx pins channels data is output on. Default value: 1.

NOTE: The adi,data-lines value is determined by the configuration of the AD7768/AD7768-4 chip’s FORMATx pins. These pins are read on power-up and dictate the number of data lines (DOUTx) on which the ADC conversions are output.

Function

File

AD7768 Device Tree

zynq-zed-adv7511-ad7768.dts

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.

Tip

An example program which uses the interface can be found here:

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
total 0
drwxr-xr-x 2 root root    0 Apr  2 21:43 buffer
drwxr-xr-x 2 root root    0 Apr  2 21:43 buffer0
-r--r--r-- 1 root root 4096 Apr  2 21:43 dev
-rw-r--r-- 1 root root 4096 Apr  2 21:43 filter_type
-r--r--r-- 1 root root 4096 Apr  2 21:43 filter_type_available
-rw-r--r-- 1 root root 4096 Apr  2 21:43 in_voltage_scale
-r--r--r-- 1 root root 4096 Apr  2 21:43 name
lrwxrwxrwx 1 root root    0 Apr  2 21:43 of_node -> ../../../../../../../../firmware/devicetree/base/axi/spi@e0006000/adc@0
drwxr-xr-x 2 root root    0 Apr  2 21:43 power
-rw-r--r-- 1 root root 4096 Apr  2 21:43 power_mode
-r--r--r-- 1 root root 4096 Apr  2 21:43 power_mode_available
-rw-r--r-- 1 root root 4096 Apr  2 21:43 sampling_frequency
-r--r--r-- 1 root root 4096 Apr  2 21:43 sampling_frequency_available
drwxr-xr-x 2 root root    0 Apr  2 21:42 scan_elements
lrwxrwxrwx 1 root root    0 Apr  2 21:42 subsystem -> ../../../../../../../../bus/iio
-rw-r--r-- 1 root root 4096 Apr  2 21:42 uevent

Show device name

root:/sys/bus/iio/devices/iio:device0> cat name
ad7768

Show scale

Description: scale to be applied to in_voltage0_raw in order to obtain the measured voltage in millivolts.

root:/sys/bus/iio/devices/iio:device0> cat in_voltage_scale
0.000488281

More Information