This version (06 Nov 2023 11:41) was approved by Ana-Maria Cusco.The Previously approved version (06 Nov 2023 11:16) is available.
Table of Contents
AD7768 IIO Precision ADC Linux Driver
Supported Devices
Evaluation Boards
Description
This is a Linux industrial I/O (IIO) 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 IIO for more information.
Source Code
Status
| Source | Mainlined? |
|---|---|
| git | [In progress…] |
Files
| Function | File |
|---|---|
| driver | master/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:
This specifies any shell prompt running on the target
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
This specifies any shell prompt running on the target
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.
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0> cat in_voltage_scale 0.000488281
More Information
- IIO mailing list: linux [dash] iio [at] vger [dot] kernel [dot] org
resources/tools-software/linux-drivers/iio-adc/ad7768.txt · Last modified: 06 Nov 2023 11:41 by Ana-Maria Cusco