Using AD7949 with pyadi-iio

AD7949 is supported by the AD7689 class pyadi-iio/adi/ad7689.py at 24b753e22e5e3c440a8dc06941ed884db3e9fe8e · analogdevicesinc/pyadi-iio (github.com)

pyadi-iio assumes you are using the IIO driver for the device. Is this the case?

-Travis

Thank you, Travis.
I got libiio and pylibiio installed.

If try to run the example code of the AD7689 I get:
"ERROR: Unable to create Avahi DNS-SD browser: Invalid host name"

Is there anything i am doing wrong? This is my first time, I am a rookie and so I will make nearly every rookie mistake.
Sorry for this in advance.

iio_info shows only the devices of the raspberry (cpu thermal and rpi volt) if this is of any importance.

Thank you
-Max

Banana said:

"ERROR: Unable to create Avahi DNS-SD browser: Invalid host name"

This likely means avahi (autodiscovery) is not correctly setup on your system. Make sure the service is running if you need that feature. Otherwise, just directly provide the constructor the URI.

Banana said:

iio_info shows only the devices of the raspberry (cpu thermal and rpi volt) if this is of any importance.

You likely don't have the driver setup. Are you using the ADI kernel (it comes with Kuiper Linux) and have you enabled the correct devicetree through the config.txt file?

-Travis

Thank you. Since the AD7689 is not listed in the project files, it is not possible for me to access the AD7949, I guess?
https://wiki.analog.com/resources/tools-software/linux-software/kuiper-linux/project-list.

The AD7949 is on a self designed RPi-Shield and is connected to the SPI-Pins.

-Max

I have installed kuiper linux. Since there is no driver for the 7949, I have added the driver.
Could you please check if this process correct?

git clone https://github.com/analogdevicesinc/linux
cd linux
git checkout rpi-5.10.y

   
-I created `Kconfig` file inside the ad7949 directory, this will appeare`/linux-adi/drivers/ad7949/Kconfig`
    
    config ad7949
    tristate "ad7949" //gives your driver description like vendor name etc.
    depends on ARM
    default y if ARM
    help
      my driver module.

-Edit `Makefile` and `Kconfig` file  at `/linux-adi/drivers/Makefile` and `/linux-adi/drivers/Kconfig`
Makefile:
     obj-$(CONFIG_AD7949)   += ad7040/
    
Kconfig:   
    source "drivers/my_drvr/Kconfig"
    
-Edited `Kconfig` file into `kernel_source/arch/arm/configs/adi_bcm2711_defconfig` since i am using RPi 4
           CONFIG_AD7949=y


-Edit build_rpi_kernel_image.sh
             DEFCONFIG=${DEFCONFIG:-adi_bcm2711_defconfig}

-run  ./build_rpi_kernel_image.sh

-Copy kernel7 to RPi /boot/

If i run lsmod it does not show up but i don't get an error message when i run modprobe ad7949.

Could you confirme this? As next step i will try to setup a device tree overlay.

Thank you!

After setting up the device tree the ad7949 gets recognized in the iio_info

analog@analog:~ $ sudo iio_info
[sudo] password for analog:
Library version: 0.24 (git tag: accb7b5)
Compiled with backends: local xml ip usb serial
IIO context created with local backend.
Backend version: 0.24 (git tag: accb7b5)
Backend description string: Linux analog 5.10.63-v7l+ #1 SMP Fri Mar 10 16:35:58 UTC 2023 armv7l
IIO context has 4 attributes:
        hw_carrier: Raspberry Pi 4 Model B Rev 1.4
        dtoverlay: vc4-kms-v3d,ad7479
        local,kernel: 5.10.63-v7l+
        uri: local:
IIO context has 4 devices:
        hwmon0: cpu_thermal
                1 channels found:
                        temp1:  (input)
                        1 channel-specific attributes found:
                                attr  0: input value: 49660
                No trigger on this device
        hwmon1: rpi_volt
                1 channels found:
                        in0:  (input)
                        1 channel-specific attributes found:
                                attr  0: lcrit_alarm value: 0
                No trigger on this device
        iio:device0: ad7949
                8 channels found:
                        voltage6:  (input)
                        2 channel-specific attributes found:
                                attr  0: raw value: 16383
                                attr  1: scale ERROR: Invalid argument (22)
                        voltage3:  (input)
                        2 channel-specific attributes found:
                                attr  0: raw value: 0
                                attr  1: scale ERROR: Invalid argument (22)
                        voltage7:  (input)
                        2 channel-specific attributes found:
                                attr  0: raw value: 16383
                                attr  1: scale ERROR: Invalid argument (22)
                        voltage0:  (input)
                        2 channel-specific attributes found:
                                attr  0: raw value: 0
                                attr  1: scale ERROR: Invalid argument (22)
                        voltage4:  (input)
                        2 channel-specific attributes found:
                                attr  0: raw value: 0
                                attr  1: scale ERROR: Invalid argument (22)
                        voltage1:  (input)
                        2 channel-specific attributes found:
                                attr  0: raw value: 250
                                attr  1: scale ERROR: Invalid argument (22)
                        voltage5:  (input)
                        2 channel-specific attributes found:
                                attr  0: raw value: 16383
                                attr  1: scale ERROR: Invalid argument (22)
                        voltage2:  (input)
                        2 channel-specific attributes found:
                                attr  0: raw value: 0
                                attr  1: scale ERROR: Invalid argument (22)
                1 debug attributes found:
                                debug attr  0: direct_reg_access value: 0x3D79
                No trigger on this device
        iio_sysfs_trigger:
                0 channels found:
                2 device-specific attributes found:
                                attr  0: add_trigger ERROR: Permission denied (13)
                                attr  1: remove_trigger ERROR: Permission denied (13)
                No trigger on this device

I can access the ad7949 via python but cannot ad7949.rx().

Is there anything I have forgotten in my dts-file or what you cause this issue. Thank you a lot.

/dts-v1/;
/plugin/;

/ {
        compatible = "brcm,bcm2708", "brcm,bcm2709";


        fragment@0 {
                target = <&spi0>;
                __overlay__ {
                        #address-cells = <1>;
                        #size-cells = <0>;
                        status = "okay";

                        ad7949@0{
                                #clock-cells = <0>;
                                compatible = "ad7949";
                                reg = <0>;
                                spi-max-frequency = <1000000>;
                                spi-cpol;
                                vref-supply = <4096000>;
                        };
                };
        };
};

Moved to Linux.

-Travis

Hi Max,

Can you try removing `spi-cpol;` from the device tree overlay?

The devicetree binding documentation on ADI linux fork does not list the spi-cpol property.

Also, in every place cpol appears in ad7949 datasheet it is set to zero (along with cpha property) or it is set to one (also along with the cpha property).

The linux driver doesn't seem to handle the busy indicator functionality (which is the case for cpol == cpha == 1) so I would recommend removing cpol property from the device tree which will result in having default cpol == cpha == 0.

Hope that helps.

Hi machschmitt,

Thank you for your kind answer. I removed 'spi-cpol' and also tried to set 'spi-mode' = <0>, which should result in cpol == cpha == 0. Both did not help.

Also could there be a problem with a wrong keyword in the overlay? I am stating vref-supply, but the documentation refers to adi,internal-ref-microvolt - could this be an issue.

Also, I noticed if I  'watch iio_info' the raw values are changing randomly without any voltage attached (compatible = "brcm,bcm2708"). After that i tried the same thing with an overlay compatible = <brcm, bcm2711>, since I am using it with a Raspberry Pi 4. After that, the iio_info raw_values do not change any longer.

At the moment it is quite frustrating because I don't know if the overlay, the driver or something else is causing this error message.

Thanks anyway
-Max

Added
    fragment@0 {
        target = "/";
        __overlay__ {
            adc_vref: fixedregulator@0 {
                compatible = "regulator-fixed";
                regulator-name = "fixed-supply";
                regulator-min-microvolt = <xxx>;
                regulator-max-microvolt = <xxx>;
                regulator-boot-on;
            };

to the overlay. see also:
https://ez.analog.com/linux-software-drivers/f/q-a/87850/ad7193-driver-with-raspberry-pi