This version (18 Apr 2023 09:56) was approved by Nuno Sá.The Previously approved version (17 Aug 2022 11:17) is available.
Table of Contents
AD74413R/AD74412R Quad-Channel, Software Configurable, Input and Output Circuit Linux Driver
Supported Devices
Evaluation Boards
Source Code
Status
Files
| Function | File |
|---|---|
| core driver | ad74413r.c |
| Documentation | adi,ad74413r.yaml |
Example device tree
| Function | File |
|---|---|
| dts | rpi-ad74413r-overlay.dts |
Driver testing
When configured with channel 0 as voltage output, channel 1 as current output, channel 2 as voltage input and channel 3 as current input, the following structure is created under the corresponding IIO device.
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 drwxr-xr-x 2 root root 0 Aug 17 09:56 buffer -r--r--r-- 1 root root 4096 Aug 17 09:56 dev -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_current0_offset -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_current0_raw -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_current0_sampling_frequency -r--r--r-- 1 root root 4096 Aug 17 09:56 in_current0_sampling_frequency_available -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_current0_scale -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_current3_offset -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_current3_raw -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_current3_sampling_frequency -r--r--r-- 1 root root 4096 Aug 17 09:56 in_current3_sampling_frequency_available -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_current3_scale -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_voltage1_offset -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_voltage1_raw -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_voltage1_sampling_frequency -r--r--r-- 1 root root 4096 Aug 17 09:56 in_voltage1_sampling_frequency_available -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_voltage1_scale -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_voltage2_offset -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_voltage2_raw -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_voltage2_sampling_frequency -r--r--r-- 1 root root 4096 Aug 17 09:56 in_voltage2_sampling_frequency_available -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_voltage2_scale -r--r--r-- 1 root root 4096 Aug 17 09:56 name lrwxrwxrwx 1 root root 0 Aug 17 09:56 of_node -> ../../../../../../../../firmware/devicetree/base/soc/spi@7e204000/ad74413r@0 -rw-r--r-- 1 root root 4096 Aug 17 09:56 out_current1_raw -rw-r--r-- 1 root root 4096 Aug 17 09:56 out_current1_scale -rw-r--r-- 1 root root 4096 Aug 17 09:56 out_voltage0_raw -rw-r--r-- 1 root root 4096 Aug 17 09:56 out_voltage0_scale drwxr-xr-x 2 root root 0 Aug 17 09:56 power drwxr-xr-x 2 root root 0 Aug 17 09:56 scan_elements lrwxrwxrwx 1 root root 0 Aug 17 09:56 subsystem -> ../../../../../../../../bus/iio drwxr-xr-x 2 root root 0 Aug 17 09:56 trigger -rw-r--r-- 1 root root 4096 Aug 17 09:56 uevent
Show device name
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0> cat name ad74413r
Show raw measurement
Description:
Raw measurement of current on channel 0.
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0> cat in_current0_raw 4608
Show scale
Description:
Scale to be applied to the raw measurement of current on channel 0 in order to obtain the actual current.
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0> cat in_current0_scale 0.001525902
Set sampling frequency
Description:
Show available sampling frequencies and select one for channel 0.
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0> cat in_current0_sampling_frequency_available 10 20 1200 4800 root:/sys/bus/iio/devices/iio:device0> cat in_current0_sampling_frequency 20 root:/sys/bus/iio/devices/iio:device0> echo 4800 > in_current0_sampling_frequency root:/sys/bus/iio/devices/iio:device0> cat in_current0_sampling_frequency 4800
Buffer management
Description:
The scan_elements directory contains interfaces for elements that will be captured for a single triggered sample set in the buffer
This specifies any shell prompt running on the target
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 Aug 17 09:56 in_current0_en -r--r--r-- 1 root root 4096 Aug 17 09:56 in_current0_index -r--r--r-- 1 root root 4096 Aug 17 09:56 in_current0_type -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_current3_en -r--r--r-- 1 root root 4096 Aug 17 09:56 in_current3_index -r--r--r-- 1 root root 4096 Aug 17 09:56 in_current3_type -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_voltage1_en -r--r--r-- 1 root root 4096 Aug 17 09:56 in_voltage1_index -r--r--r-- 1 root root 4096 Aug 17 09:56 in_voltage1_type -rw-r--r-- 1 root root 4096 Aug 17 09:56 in_voltage2_en -r--r--r-- 1 root root 4096 Aug 17 09:56 in_voltage2_index -r--r--r-- 1 root root 4096 Aug 17 09:56 in_voltage2_type
Before enabling the buffer, a few steps need to be completed.
- For example, if we want to capture all input channels, we need to enable the scan elements:
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0/scan_elements> echo 1 > in_current0_en root:/sys/bus/iio/devices/iio:device0/scan_elements> echo 1 > in_voltage1_en root:/sys/bus/iio/devices/iio:device0/scan_elements> echo 1 > in_voltage2_en root:/sys/bus/iio/devices/iio:device0/scan_elements> echo 1 > in_current3_en
This specifies any shell prompt running on the target
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 Aug 17 09:56 data_available -rw-r--r-- 1 root root 4096 Aug 17 09:56 enable -rw-r--r-- 1 root root 4096 Aug 17 09:56 length -rw-r--r-- 1 root root 4096 Aug 17 09:56 watermark
- Set the buffer length:
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0/buffer> echo 1024 > length
- Set the watermak:
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0/buffer> echo 512 > watermark
- Enable the buffer:
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0/buffer> echo 1 > enable
- Read the samples:
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0/buffer> cat /dev/iio:device0
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.
This specifies any shell prompt running on the target
root:/> /sys/kernel/debug/iio/iio:device0/ root:/sys/kernel/debug/iio/iio:device0> ls direct_reg_access direct_reg_access
Reading
This specifies any shell prompt running on the target
root:/sys/kernel/debug/iio/iio:device0> echo 0x45 > direct_reg_access root:/sys/kernel/debug/iio/iio:device0> cat direct_reg_access 0x00
Writing
Write ADDRESS VALUE
This specifies any shell prompt running on the target
root@analog:/sys/kernel/debug/iio/iio:device0> echo 0x45 0xADAD > direct_reg_access root@analog:/sys/kernel/debug/iio/iio:device0> cat direct_reg_access 0xADAD
More Information
- IIO mailing list: linux [dash] iio [at] vger [dot] kernel [dot] org
resources/tools-software/linux-drivers/iio-addac/ad74413r.txt · Last modified: 18 Apr 2023 09:56 by Nuno Sá