AD7193 Driver with Raspberry Pi

Question

Hi,

So i have been trying to to establish SPI communication between AD7193 and Raspberry pi 3. I'm using the Yocto-rpi image for this purpose. This is procedure i followed but facing some issues:-

1. Enabled the ad7193 driver in menuconfig.

2. Added the patch file in the drivers/staging/iio/adc/ad7192.c for it to support device tree.

3.Created an overlay. dts file for this is /boot/dts/ as follows

/dts-v1/;
/plugin/;

/ {
compatible = "brcm,bcm2835", "brcm,bcm2708", "brcm,bcm2709";

        fragment@0 {
                target = <&spi0>;
                __overlay__ {
                        status = "okay";
                };
        };

        fragment@1 {
                target = <&spidev0>;
                __overlay__ {
                        status = "disabled";
                };
        };

        fragment@2 {
                target = <&spidev1>;
                __overlay__ {
                        status = "disabled";
                };
        };

        fragment@3 {
                target = <&gpio>;
                __overlay__ {
                        ad7193_pins: ad7193_pins {
                                brcm,pins = <45>;
                                brcm,function = <0>;
                                brcm,pull = <0>;
                        };
                };
        };

        fragment@4 {
                target = <&spi0>;
                __overlay__ {
                        /* needed to avoid dtc warning */
                        #address-cells = <1>;
                        #size-cells = <0>;

                        adc: ad7192@0{
                                compatible = "adi,ad7192";
                                reg = <0>;
                                pinctrl-names = "default";
                                pinctrl-0 = <&ad7193_pins>;

                                spi-max-frequency = <1000000>;
                                spi-cpha;
                                spi-cpol;
                                irq-gpio = <&gpio 45 0x2>; /* IRQF_TRIGGER_FALLING */
                                interrupts = <45 0>; /* high-to-low edge triggered */
                                interrupt-parent = <&gpio>;
                                adi,reference-voltage-mv = <3300>;
                                adi,clock-source-select = <2>;
                                adi,refin2-enable;
                                adi,unipolar-enable;
                                status = "okay";
                        };
                };
        };
};

4. Added this overlay.dts file to bb.append file and rebuild the kernel and enable the overlay file in /boot/config.txt in the target.

5. The driver is loaded but i keep getting setup failed and spi0.0 supply vcc not found, using dummy regulator
ad7192 spi0.0: setup failed

ad7192: probe of spi0.0 failed with error -5

I'm attaching the image below please let me know what i'm doing wrong.

Note:- I have connected AGND,CS,SCLK,Din,Dout/Rdy to the respective pins in raspberry pi 3.

Thanks in advance.

-SK

ADIApproved · Accepted Answer

Hey, I think we solved it. Turns out the issue is related to the parting of the device-tree file, the adi,clock-source-select is 8 bits, so in the device-tree it needs to be specified. For testing, we used an AD7190 chip, that runs on the same driver as AD7192, AD71923 & AD7195. The wiring is as presented below: The DTS file is : /dts-v1/; /plugin/; / { compatible = "brcm,bcm2835", "brcm,bcm2708", "brcm,bcm2709"; fragment@0 { target-path = "/"; __overlay__ { adc_vref: fixedregulator@0 { reg = <0>; compatible = "regulator-fixed"; regulator-name = "fixed-supply"; regulator-min-microvolt = <3300000>; regulator-max-microvolt = <3300000>; regulator-boot-on; }; }; }; fragment@1 { target = <&spidev0>; __overlay__ { status = "disabled"; }; }; fragment@2 { target = <&spidev1>; __overlay__ { status = "disabled"; }; }; fragment@3 { target = <&spi0>; __overlay__ { ad7190@0 { compatible = "ad7190"; reg = <0>; spi-max-frequency = <1000000>; spi-cpol; spi-cpha; #interrupt-cells = <2>; interrupts = <25 0x2>; interrupt-parent = <&gpio>; vcc-supply = <&adc_vref>; adi,clock-source-select = /bits/ 8 <2>; /* adi,reference-voltage-mv = /bits/ 16 <3300>; adi,refin2-pins-enable; adi,rejection-60-Hz-enable; adi,chop-enable; adi,buffer-enable; adi,burnout-currents-enable; adi,sinc3-filter-enable; adi,unipolar-enable;*/ }; }; }; }; What's different from the initial DTS: corrected target = "/" ; to target-path = "/"; in fragment@0 most importantly: adi,clock-source-select = /bits/ 8 <2>; the clock-source-select was zero because [ if bits is unspecified ] then the device-tree logic assumes it's a 32 bit value I commented out the other bits ; I'll probably test them later I was able to read from the device: root@OpenWrt:/sys/devices/platform/soc/3f204000.spi/spi_master/spi0/spi0.0/iio:device0# cat in_temp0_raw 9232793 Attached is also the patch that I used on top of an OpenWrt build/kernel. I tried to build an image via Yocto to be a bit more on-par with your environment, but I hit a few roadblocks there, and I decided to stick with OpenWrt [since I'm more familiar with that env]. Attached are also my scripts that I created [ for my personal use ] to automate some parts for building Yocto & OpenWrt. Though both generated images run fine on the RPI3 board, I only managed to setup overlays on OpenWrt [well, they're on by default I think]. We'll see maybe about updating the kernel documentation or maybe updating the ad7192.c driver to use 32 bits for the adi,clock-source-select field. Still not decided yet. Hope this helps. Alex)

SKR · Answer

Hi, 
 Type the menuconfig command then select the Device drivers option followed by staging drivers followed by IIO drivers and in the you will find your second option as analog to digital converters . Click on that you will find the ad7193 as the third option, press M and save it . Your driver will be enabled. You would have found this step by step procedure in the link provided few comments before clearly, please read it properly.

ADIApproved · Answer

the AD7192 driver supports 4 ADCs : AD7190, AD7192, AD7193 & AD7195; 
 so, you need to use that driver for AD7193 as well ;

ADIApproved · Answer

hey, 
 there's an entry in the ADI wiki regarding this: AD7192 IIO High Precision ADC Linux Driver [Analog Devices Wiki] 
 other info there may help ;

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AD7193 Driver with Raspberry Pi