Hi Nordic,
I'm using custom board based on nrf52840 SoC. After migrating the SDK, the original device tree configuration for ADC became unavailable, but I failed to find relevant explanations in the SDK migration guide. Through my own attempts, I modified the original dts that worked properly in ncs3.1.1 into a new dts, and it now works properly.
The old dts:
/ {
vbatt {
compatible = "voltage-divider";
io-channels = <&adc 7>;
output-ohms = <1000000>;
full-ohms = <2000000>;
};
};
&adc {
status = "okay";
};
The new dts:
/ {
vbatt {
compatible = "voltage-divider";
io-channels = <&adc 6>;
output-ohms = <1000000>;
full-ohms = <2000000>;
};
};
&adc {
#address-cells = <1>;
#size-cells = <0>;
status = "okay";
channel@6 {
reg = <6>;
zephyr,gain = "ADC_GAIN_1_6";
zephyr,reference = "ADC_REF_INTERNAL";
zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
zephyr,input-positive = <NRF_SAADC_AIN7>; /* P0.31 on nRF52840 */
zephyr,resolution = <12>;
};
};
These are two problems I encountered during my testing.
1.This error occurs during ADC setup when using channel 7 in NCS 3.2.0: <err> adc_nrfx_saadc: Cannot configure channel 0: -22. Normally, all 8 channels should be usable properly. I don't know why the error occurs in NCS 3.2.0.
2.If I do not use channel 6 but other channels such as channel 0 and channel 1, the voltage collected using adc_raw_to_millivolts(); will not be valid data. I do not see any other ADC channels being used in the final generated zephyr.dts, so I am not sure what exactly causes only channel 6 to be able to collect valid battery level data.
I hope you guys can answer my questions. Thank you very much.
