This version (07 Jan 2021 08:47) was approved by Ioana Chelaru.The Previously approved version (18 Jul 2018 15:25) is available.
Table of Contents
AD5770R IIO DAC Linux Driver
Supported Devices
This driver supports the
Evaluation Boards
Description
This is a Linux industrial I/O (IIO) subsystem driver, targeting multi-channel serial interface DACs. 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 | [No] |
Devicetree
Required devicetree properties for the AD5770R:
- compatible: Must be “adi,ad5770r”
- reg: SPI chip select number for the device
- spi-max-frequency: Max SPI frequency to use (< 10000000)
- child nodes: Each child node represents one channel.
Optional properties:
- vref: Specify the voltage of the external reference used.
- reset-gpios: GPIO spec for the RESET pin. If specified, it will be asserted during driver probe.
ad5770r@0 {
compatible = "ad5770r";
reg = <0>;
spi-max-frequency = <1000000>;
vref-supply = <&vref>;
reset-gpios = <&gpio 22 0>;
channel@0 {
num = <0>;
adi,range-microamp = <0 300000>;
};
channel@1 {
num = <1>;
adi,range-microamp = <0 140000>;
};
channel@2 {
num = <2>;
adi,range-microamp = <0 55000>;
};
channel@3 {
num = <3>;
adi,range-microamp = <0 45000>;
};
channel@4 {
num = <4>;
adi,range-microamp = <0 45000>;
};
channel@5 {
num = <5>;
adi,range-microamp = <0 45000>;
};
};
vref: fixedregulator@0 {
compatible = "regulator-fixed";
regulator-name = "fixed-supply";
regulator-min-microvolt = <1250000>;
regulator-max-microvolt = <1250000>;
};
Adding Linux driver support
Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)
Linux Kernel Configuration
Device Drivers --->
...
<*> Industrial I/O support --->
--- Industrial I/O support
...
Digital to analog converters --->
...
<*> Analog Devices AD5770R IDAC driver
...
...
...
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.
This specifies any shell prompt running on the target
pi@raspberrypi:/sys/bus/iio/devices/iio:device0 $ cd /sys/bus/iio/devices/ pi@raspberrypi:/sys/bus/iio/devices $ ls iio:device0 iio:device1 pi@raspberrypi:/sys/bus/iio/devices $ cd iio\:device0 pi@raspberrypi:/sys/bus/iio/devices/iio:device0 $ ls -l total 0 -r--r--r-- 1 root root 4096 Jul 18 12:12 dev -r--r--r-- 1 root root 4096 Jul 18 12:12 name lrwxrwxrwx 1 root root 0 Jul 18 12:12 of_node -> ../../../../../../../../firmware/devicetree/base/soc/spi@7e204000/ad5770r@0 -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current0_filter_low_pass_3db_frequency -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current0_powerdown -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current0_raw -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current0_scale -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current1_filter_low_pass_3db_frequency -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current1_powerdown -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current1_raw -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current1_scale -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current2_filter_low_pass_3db_frequency -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current2_powerdown -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current2_raw -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current2_scale -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current3_filter_low_pass_3db_frequency -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current3_powerdown -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current3_raw -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current3_scale -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current4_filter_low_pass_3db_frequency -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current4_powerdown -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current4_raw -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current4_scale -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current5_filter_low_pass_3db_frequency -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current5_powerdown -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current5_raw -rw-r--r-- 1 root root 4096 Jul 18 12:12 out_current5_scale -r--r--r-- 1 root root 4096 Jul 18 12:12 out_current_filter_low_pass_3db_frequency_available drwxr-xr-x 2 root root 0 Jul 18 12:12 power lrwxrwxrwx 1 root root 0 Jul 18 12:12 subsystem -> ../../../../../../../../bus/iio -rw-r--r-- 1 root root 4096 Jul 18 12:12 uevent
Show device name
This specifies any shell prompt running on the target
pi@raspberrypi:/sys/bus/iio/devices/iio:device0 $ cat name ad5770r
Show scale
Description:
/sys/bus/iio/devices/iio:deviceX/out_currentY_scale
scale to be applied to out_currentY_raw in order to obtain the measured current in milliamps.
This specifies any shell prompt running on the target
root@raspberrypi:/sys/bus/iio/devices/iio:device0# cat out_current0_scale 0.018310546
Set channel Y output current
Description:
/sys/bus/iio/devices/iio:deviceX/out_currentY_raw
Raw (unscaled, no bias etc.) output current for channel Y.
This specifies any shell prompt running on the target
root@raspberrypi:/sys/bus/iio/devices/iio:device0# echo 5000 > out_current0_raw
I = out_current0_raw * out_current0_scale = 5000 * 0,018310546 = 91,55273 mA
Enable power down mode for the device
/sys/bus/iio/devices/iio:deviceX/out_currentY_powerdown
Description:
Writing 1 causes channel Y to enter power down mode. Clearing returns to
normal operation.
This specifies any shell prompt running on the target
root@raspberrypi:/sys/bus/iio/devices/iio:device0# echo 1 > out_current0_powerdown root@raspberrypi:/sys/bus/iio/devices/iio:device0# cat out_current0_powerdown 1 root@raspberrypi:/sys/bus/iio/devices/iio:device0# echo 0 > out_current0_powerdown root@raspberrypi:/sys/bus/iio/devices/iio:device0# cat out_current0_powerdown 0
Show available filter frequencies
/sys/bus/iio/devices/iio:deviceX/out_current_filter_low_pass_3db_frequency_available
Description:
Contains available filter frequencies.
This specifies any shell prompt running on the target
root@raspberrypi:/sys/bus/iio/devices/iio:device0# cat out_current_filter_low_pass_3db_frequency_available 153 357 715 1400 2800 262000
Set channel Y filter frequency
/sys/bus/iio/devices/iio:deviceX/out_current0_filter_low_pass_3db_frequency
Description:
Write filter value to channel Y.
This specifies any shell prompt running on the target
root@raspberrypi:/sys/bus/iio/devices/iio:device0# cat out_current0_filter_low_pass_3db_frequency 262000 root@raspberrypi:/sys/bus/iio/devices/iio:device0# echo 1000 > out_current0_filter_low_pass_3db_frequency root@raspberrypi:/sys/bus/iio/devices/iio:device0# cat out_current0_filter_low_pass_3db_frequency 1400
More Information
- IIO mailing list: linux [dash] iio [at] vger [dot] kernel [dot] org
resources/tools-software/linux-drivers/iio-dac/ad5770r.txt · Last modified: 07 Jan 2021 08:47 by Ioana Chelaru