Trying to read the voltage of two ADC inputs, each with different voltage divider circuits.
Using zephyr/samples/boards/nrf/battery, I can get the correct voltage if I pick one input or the other. However, if I copy battery.c to battery2.c changing the ADC input, I get incorrect values from both inputs.
If I use zephyr/samples/drivers/adc, the wrong voltages are displayed and changing one input affects both values. (Should be 15V and 3.9V)
ADC reading: - adc@e000, channel 4: 8779 = 1928 mV - adc@e000, channel 6: 8745 = 1921 mV ADC reading: - adc@e000, channel 4: 8790 = 1931 mV - adc@e000, channel 6: 8740 = 1920 mV ADC reading: - adc@e000, channel 4: 8774 = 1927 mV - adc@e000, channel 6: 8738 = 1919 mV
DTS:
/ {
zephyr,user {
io-channels = <&adc 4>, <&adc 6>;
};
};
&adc {
status = "okay";
#address-cells = <1>;
#size-cells = <0>;
channel@4 {
reg = <4>;
zephyr,gain = "ADC_GAIN_1_6";
zephyr,reference = "ADC_REF_INTERNAL";
zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
zephyr,input-positive = <NRF_SAADC_VDD>;
zephyr,resolution = <14>;
zephyr,oversampling = <8>;
};
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_VDD>;
zephyr,resolution = <14>;
zephyr,oversampling = <8>;
};
};
/ {
vbatt {
compatible = "voltage-divider";
io-channels = <&adc 4>;
output-ohms = <100000>;
full-ohms = <(100000 + 100000)>;
power-gpios = <&gpio0 18 GPIO_ACTIVE_HIGH>;
};
vin {
compatible = "voltage-divider";
io-channels = <&adc 6>;
output-ohms = <100000>;
full-ohms = <(100000 + 12000)>;
};
};
Any idea why the Zephyr ADC is displaying the wrong values or how to read multiple inputs with the nRF example?
