iMX6ULL adc calibration

barry_chen — Wed, 13 Nov 2019 07:12:27 GMT

Hi,dears,

I had the same problem as this little friend:

My soc is iMx6uLL,but I tested at EVK board. EVK had this problem. So I think it has nothing to do with PCB.

Listed my config:

dts:

&adc1 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_adc1>;
vref-supply = <&reg_vref_3v3>;
num-channels = <2>;
status = "okay";
};

pinctrl_adc1: adc1grp {
fsl,pins = <
MX6UL_PAD_GPIO1_IO08__GPIO1_IO08 0xb0
MX6UL_PAD_GPIO1_IO09__GPIO1_IO09 0xb0
>;
};

vf610_adc.c :
static const struct iio_chan_spec vf610_adc_iio_channels[] = {
VF610_ADC_CHAN(9, IIO_VOLTAGE),
VF610_ADC_CHAN(8, IIO_VOLTAGE),

};

#cat /sys/bus/iio/devices/iio\:device0/in_voltage8_raw
3976

In my PCBA board ,ADC_VREFH is OK,3.3V, but why cat out is 3976?

When I connected 1.8V, cat out value is 2233.

It's strange.

Re: iMX6ULL adc calibration

igorpadykov — Wed, 13 Nov 2019 09:50:32 GMT

Hi cheng

adc is not used in linux as it is used in sdk, so one can test it in sdk:

SDK2.2_iMX6ULL_WIN

Best regards
igor
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topic iMX6ULL adc calibration in i.MX Processors

iMX6ULL adc calibration

Re: iMX6ULL adc calibration

SDK2.2_iMX6ULL_WIN