npm1300 zephyr driver documentation

[Yaxit]

Hi,

I'm developing now on a custom board with the npm1300. I see that there are two examples in NCS based on zephyr's drivers. Moreover, the nPM powerUP desktop application only exports an overlay file for use in the device tree with the zephyr driver.

However, I could not find detailed documentation of the Zephyr API's implementation of the driver, which callbacks are implemented and which ones are not etc.

For example, I can turn the LEDs on and off with the led driver, but `led_blink` doesn't do anything. I'm basically looking for documentation describing this stuff, since trial and error takes way too long for a chip with so many functionalities.

On a similar note, are these functions even thread-safe? I'm happy to use these drivers but only if I can trust them :D

Thank you!

[Achim Kraus]

I'm currently on the same "mission".

For the LED there is a sample:

nrf/samples/pmic/native/npm1300_one_button

and for the charger as well.

nrf/samples/pmic/native/npm1300_fuel_gauge

Not sure, why Nordic decided to not implement the charger API and used that more or less proprietary one.

I currently stuck in decoding the

sensor_channel_get(charger, SENSOR_CHAN_NPM1300_CHARGER_STATUS, &value);

for now it seems to be a rather incomplete API.

[Robin M Saltnes]

fuel gauge is not the charger, The Fuel gauge sample demonstrates how to calculate the state of charge of a battery.

The nPM1300's charger uses standard Zephyr API, and can be used in any sample by using the correct settings in the overlay.  

[Achim Kraus]

Does this apply for ncs 2.6.1 or only newer ncs?

Do you have an example of the "correct settings in the overlay"?

That's from the overlay I'm using:

    npm1300_pmic: pmic@6b {
        compatible = "nordic,npm1300";
        reg = <0x6b>;

        npm1300_gpio: gpio-controller {
            compatible = "nordic,npm1300-gpio";
            gpio-controller;
            #gpio-cells = <2>;
            ngpios = <5>;
        };

        npm1300_leds: leds {
            compatible = "nordic,npm1300-led";
            nordic,led0-mode = "error";
            nordic,led1-mode = "charging";
            nordic,led2-mode = "host";
        };

        npm1300_charger: charger {
            compatible = "nordic,npm1300-charger";
            term-microvolt = <4150000>;
            term-warm-microvolt = <4000000>;
            current-microamp = <800000>;
            dischg-limit-microamp = <1000000>;
            vbus-limit-microamp = <1000000>;
            thermistor-ohms = <10000>;
            thermistor-beta = <3380>;
            charging-enable;
        };

        npm1300_regulators: regulators {
            compatible = "nordic,npm1300-regulator";

            npm1300_buck1: BUCK1 {
                regulator-min-microvolt = <2700000>;
                regulator-max-microvolt = <3300000>;
                regulator-always-on;
            };

            npm1300_buck2: BUCK2 {
                regulator-min-microvolt = <3300000>;
                regulator-max-microvolt = <3300000>;
            };


        };
    };

[Robin M Saltnes]

To me the charger settings looks fine, what problem are you experiencing with the charger?

[Achim Kraus]

Using "zephyr/samples/charger" NCS 2.6.1 ?

"charger_get_prop" was always reporting an error. I think it was "-ENOTSUP" but I may have been an other error.

To be frank:

With the years I'm got used to check rather the nrf samples and there I found the "fuel_gauge", which doesn't use the "charger_get_prop" and instead uses the "sensor_channel_get". That works for me and the value reported as status are then contained in the datasheet.

[Robin M Saltnes]

You are right, it looks like the nPM1300 charger driver is using the zephyr sensor API. I will forward that this is confusing to the developers of the drivers.  

Update from devs: It looks like the Zephyr drvice driver api for chargers did not exist when we started developed the drivers for the nPM1300 charger, and that's why the sensor device driver API was selected.

Thanks for bringing this to my attention. 

[Achim Kraus]

Thanks for confirming my experience.

As I wrote, usually I go straight forward to the nrf samples. That was one of the rare cases, where I started with the zephyr samples.