IMX6UL ADC test from user space

[anshulkhare]

Hi All,

I want to do an adc test on imx6ul board. But, I am not able to see anything under /sys/bus/iio/devices/.

I have enabled the ADC support in kernel configurations.

My dtsi(imx6ul.dtsi) file contains :

adc1: adc@02198000 {
compatible = "fsl,imx6ul-adc", "fsl,vf610-adc";
reg = <0x02198000 0x4000>;
interrupts = <GIC_SPI 100 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&clks IMX6UL_CLK_ADC1>;
num-channels = <2>;
clock-names = "adc";
status = "disabled";
};

Is there anything more to be done to see the devices in /sys/bus/iio/devices/.

Could anyone kindly help me out on this ?

[fabio_poiatti]

Hi,

I tried the MX6UL_PAD_GPIO1_IO04__GPIO1_IO04 as ADC_IN4 connecting the physical pin to 3.3V

or 0V but I read always a number near 4095 as I read a different gpio pin ...

Any suggestion?

Thanks

[huf]

num-channels = <5>;

and then try: cat  /sys/bus/iio/devices/iio\:device0/in_voltage4_raw

[fabio_poiatti]

It is working :-)

many thanks

[huf]

adc1: adc@02198000 {
compatible = "fsl,imx6ul-adc", "fsl,vf610-adc";
reg = <0x02198000 0x4000>;
interrupts = <GIC_SPI 100 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&clks IMX6UL_CLK_ADC1>;
num-channels = <1>;
clock-names = "adc";
status = "disabled";
};

&adc1 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_adc1>;
vref-supply = <&reg_vref_3v3>;
status = "okay";
};

pinctrl_adc1 define the pins.

I think the key is: status = "okay";

you will see /sys/bus/iio/devices/iio:device0，document is wrong.

[fabio_poiatti]

I don't se anything ...

is it correct the pin definition

&iomuxc {
imx6ul-ccimx6ul {
/* Uncomment specific pins of the ADC channels enabled in 'adc-ch-list' */
pinctrl_adc1: adc1grp {
fsl,pins = <
/* GPIO1_4/ADC1_IN4 (pin 7 of the expansion header) */
MX6UL_PAD_GPIO1_IO04__GPIO1_IO04 0x80
>;
};
};

thanks

[huf]

my dts：

pinctrl_adc1: adc1grp {
fsl,pins = <
MX6UL_PAD_GPIO1_IO03__GPIO1_IO03 0x1b0b0
>;
};  

ADC_IN4, the i.MX Pins Tools recommed configuration is

MX6UL_PAD_GPIO1_IO04__GPIO1_IO04           0x000010B0

adn maybe your kernel configuration is not correct.

[fabio_poiatti]

now I see  something but I have some doubts regarding the meaning of pinctrl_adc1 ...

1) in your example you set pinctrl_adc1 as MX6UL_PAD_GPIO1_IO03__GPIO1_IO03 with value 0x10B0

is it correct? is the initial value for IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO03 register? The same for 

MX6UL_PAD_GPIO1_IO04__GPIO1_IO04

2) how is possible to set the adc input channel? Or in other words ... how is the relationship

beetwen the adc input channel, the bit0.4 of ADC1.HC0.ADCH register and the setting as

pinctrl_adc1 in the DTB file?

thanks

[fabio_poiatti]

any news?

always in the same condition .... and I also modified the DTS file to produce the adc1 anabled ..

but always I didn't see anything in the /sys directories

Thanks

[igorpadykov]

Hi Anshul

please try procedures described in sect.53.3.3 Programming Interface

attached Linux Manual, use nxp bsps described on

https://www.nxp.com/support/developer-resources/run-time-software/i.mx-developer-resources/i.mx-6ser...

Best regards
igor
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[anshulkhare]

Hello igor,

Thank you for the suggestion. But as per the document, we have enabled freescale vf610 ADC driver as well as ADC driver for imx6 (the board we are using). Still we are not able to see any devices under /sys/bus/iio/devices/. 

Is there anything else we are supposed to do?

[igorpadykov]

Hi Anshul

 according to document interface is available at

/sys/devices/soc0/soc.1/2200000.aips-bus/

Best regards
igor

[anshulkhare]

Hi igor,

There is nothing as soc.1 under /sys/devices/soc0/.

I can see only family, machine, power(dir), revision, soc_id, subsystem(link), uevent under this directory.

[igorpadykov]

Hi Anshul

please try demo images

https://www.nxp.com/webapp/Download?colCode=L4.1.15_2.0.0_iMX6UL&appType=license&location=null 

Best regards
igor

[fabio_poiatti]

I have the same problem ... and the demo image does not work signalling a 

Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b

Any suggestion?

thanks