DAC AD5362 Issue

In the driver, it looks like you need to provide 2 reference regulators:

        [ID_AD5362] = {
                .channel_template = AD5360_CHANNEL(16),
                .num_channels = 8,
                .channels_per_group = 4,
                .num_vrefs = 2,
        },

num_vrefs is 2

the error " Invalid argument" seems to be coming from a missing regulator most likely;

you need to add these regulators in the device-tree;

even if you just specify some fixed-regulator property that has a fixed value;

In the driver, it looks like you need to provide 2 reference regulators:

        [ID_AD5362] = {
                .channel_template = AD5360_CHANNEL(16),
                .num_channels = 8,
                .channels_per_group = 4,
                .num_vrefs = 2,
        },

num_vrefs is 2

the error " Invalid argument" seems to be coming from a missing regulator most likely;

you need to add these regulators in the device-tree;

even if you just specify some fixed-regulator property that has a fixed value;

Hi aardelean,

We added vref in dts and now invalid argument is not coming and i am able to read scale property.

But, whenever i am trying update out_voltage0_raw or any other channels that value is not getting updated and hence i am not getting analog out of that channel.what changes i have to do in driver?

VKumar592 said:

root@am57xx-evm:/sys/bus/iio/devices/iio:device2# echo 1000 > out_voltage0_raw
root@am57xx-evm:/sys/bus/iio/devices/iio:device2# cat out_voltage0_raw
1024

if you try other values, do you still read 1024?

how is the board connected?

maybe reduce the SPI frequency to a few kilohertz to see if this helps; SPI sensive above 1 Mhz, and you need good connections to go to a few Mhz;

did you configure the proper SPI modes? it looks like this would need SPI mode 1 [if i am reading the datasheet correctly], so in the device-tree you'd need to set the "spi-cpha" property so that it's in mode 1.

i don't have an eval board with this chip around to test

Hi aardelean,

device tree node is as follows-

&mcspi3{
    status = "okay";
    pinctrl-names = "default";
    pinctrl-0 = <&mcspi3_pins_default>;
    ti,pindir-d0-out-d1-in;
    ti,spi-num-cs = <1>;
    dmas = <&sdma_xbar 15>,
           <&sdma_xbar 16>;
    dma-names="tx0","rx0";

    ad5362@0{
        compatible = "adi,ad5362";
        reg = <0>;
        spi-max-frequency = <10000000>;
        spi-cpha;
        vref0-supply = <&vref0>;
        vref1-supply = <&vref1>;
    };

};

contents of the registers of the DAC -

root@am57xx-evm:/sys/bus/iio/devices/iio:device2# grep "" *
dev:249:2
name:ad5362
out_voltage0_calibbias:17408
out_voltage0_calibscale:25600
out_voltage0_offset:-132096
out_voltage0_raw:1024
out_voltage0_scale:0.183105468
out_voltage1_calibbias:17536
out_voltage1_calibscale:25728
out_voltage1_offset:-132096
out_voltage1_raw:1152
out_voltage1_scale:0.183105468
out_voltage2_calibbias:17664
out_voltage2_calibscale:25856
out_voltage2_offset:-132096
out_voltage2_raw:1280
out_voltage2_scale:0.183105468
out_voltage3_calibbias:17792
out_voltage3_calibscale:25984
out_voltage3_offset:-132096
out_voltage3_raw:1408
out_voltage3_scale:0.183105468
out_voltage4_calibbias:17920
out_voltage4_calibscale:26112
out_voltage4_offset:-132608
out_voltage4_raw:1536
out_voltage4_scale:0.183105468
out_voltage5_calibbias:18048
out_voltage5_calibscale:26240
out_voltage5_offset:-132608
out_voltage5_raw:1664
out_voltage5_scale:0.183105468
out_voltage6_calibbias:18176
out_voltage6_calibscale:26368
out_voltage6_offset:-132608
out_voltage6_raw:1792
out_voltage6_scale:0.183105468
out_voltage7_calibbias:18304
out_voltage7_calibscale:26496
out_voltage7_offset:-132608
out_voltage7_raw:1920
out_voltage7_scale:0.183105468
out_voltage_powerdown:0
uevent:MAJOR=249
uevent:MINOR=2
uevent:DEVNAME=iio:device2
uevent:DEVTYPE=iio_device
root@am57xx-evm:/sys/bus/iio/devices/iio:device2#

Calibscale should be 65535 and calibbias should be 0 by default but it is not link that.

if you try other values, do you still read 1024?

yes i tried modifying this value it is not changing.

VKumar592 said:

spi-max-frequency = <10000000>;

10 Mhz is pretty high;

triy 500 khz for testing; if it works, scale it up and see where it doesn't

triy 500 khz for testing; if it works, scale it up and see where it doesn't

I changed it to 500khz but still the same issue.

Hi,

Try enabling the SPI debugging feature in linux:

- enable spi_debug from make menuconfig

See if some error outputs from spidev are received when running dmesg after trying to write to one of the out_voltageX.

If still nothing show up, can you post a waveform of an SPI write?

Hi,

SPI debugging is already enabled. Following is the log of SPI devices

oot@am57xx-evm:~# dmesg | grep spi
[    2.531099] omap2_mcspi 480b8000.spi: registered master spi1
[    2.531334] spi spi1.0: setup: speed 1000000, sample trailing edge, clk normal
[    2.531347] spi spi1.0: setup mode 1, 8 bits/w, 1000000 Hz max --> 0
[    2.531549] omap2_mcspi 480b8000.spi: registered child spi1.0
[    2.531875] omap2_mcspi 480ba000.spi: registered master spi2
[    2.532058] spi spi2.0: setup: speed 1000000, sample leading edge, clk normal
[    2.532070] spi spi2.0: setup mode 0, 8 bits/w, 1000000 Hz max --> 0
[    2.532272] omap2_mcspi 480ba000.spi: registered child spi2.0
[    2.532390] spi spi2.1: setup: speed 1000000, sample leading edge, clk normal
[    2.532401] spi spi2.1: setup mode 0, 8 bits/w, 1000000 Hz max --> 0
[    2.532592] omap2_mcspi 480ba000.spi: registered child spi2.1
[    3.424147] ads8688 spi2.0: Looking up vref-supply from device tree
[    3.424153] ads8688 spi2.0: Looking up vref-supply property in node /ocp/spi@480ba000/ads8688_1@0 failed
[    3.424186] ads8688 spi2.0: setup: speed 1000000, sample trailing edge, clk normal
[    3.424532] ads8688 spi2.1: Looking up vref-supply from device tree
[    3.424537] ads8688 spi2.1: Looking up vref-supply property in node /ocp/spi@480ba000/ads8688_2@1 failed
[    3.424563] ads8688 spi2.1: setup: speed 1000000, sample trailing edge, clk normal
[    3.424899] ad5360 spi1.0: Looking up vref0-supply from device tree
[    3.424960] ad5360 spi1.0: Looking up vref1-supply from device tree
root@am57xx-evm:~#

No errors are seen, when we try to write to /sys/bus/iio/devices/iio\:device2/out_voltage0_raw

Hi,

Can you tell us to what is SYNC connected? I see that SYNC is required to act as a CS, staying low for the duration of the write. IF SYNC does not go high after the 25th clock, transfer is considered corrupted and register won't update.

Thanks

Hi,

The issue is resolved after giving 10V vdd and -10V vss.

initially we were giving 6V VDD and -6V vss

thank you.