Using AIN0/P0.13 as a ADC pin in nRF9160

[thwcs7]

I want to use P0.13 for ADC reading.
However, I noticed that it is already used as an SCK pin in this configuration:

spi3_default: spi3_default {
group1 {
psels = <NRF_PSEL(SPIM_SCK, 0, 13)>,
<NRF_PSEL(SPIM_MISO, 0, 12)>,
<NRF_PSEL(SPIM_MOSI, 0, 11)>;
};
};

So I disabled the SPI:

&arduino_spi {
status = "disabled";
};

Then I remapped GPIO P0.13 to a new ADC channel:

&arduino_header {
gpio-map = <0 0 &gpio0 14 0>,
<1 0 &gpio0 15 0>,
...
<19 0 &gpio0 13 0>,
...
};

And I also updated the ADC mapping:

&arduino_adc {
io-channel-map = <0 &adc 1>, <1 &adc 2>, <2 &adc 3>, <3 &adc 4>, <4 &adc 5>, <5 &adc 6>, <19 &adc 7>;
};

But it seems I still cannot read ADC on pin P0.13.

Here is my voltage divider configuration:

vbatt_divider {
compatible = "voltage-divider";
io-channels = <&adc 7>; // P0.13 (AIN0)
output-ohms = <220000>;
full-ohms = <900000>;
power-gpios = <&gpio0 VOLTAGE_DIV_EN GPIO_ACTIVE_LOW>;
};

Could you please help check if I am missing or misconfiguring anything?

[Hieu]

Hi thwcs7,

What you are doing seems correct. What exactly happened when you say "I still cannot read ADC on pin P0.13"?

Are you working on the nRF9160 DK though? On the DK, P0.13 is connected to the external flash chip, so that might be why the reading is not correct.

Hieu

[thwcs7]

No, I’m using a custom board with the nRF9160-SIxA chip. I can read the ADC values, but they don't seem to accurately reflect the voltage level (in mV) that I want to measure.

[Hieu]

Could you please give more details?