nPM2100 - break-to-wake

Question

Hello everyone,

We are currently working on a project that uses the nPM2100 to power an nRF52840. Our application requires automatic enabling break-to-wake mode each time the SHPHLD pin is shorted (power switch based on the state of the SHPHLD pin)

At the moment, in our firmware (NCS 3.2.3), we are able to configure the controller through the overlay, but we do not see any way to enable this mode.

npm2100_pmic: pmic@74 {
    compatible = "nordic,npm2100";
    reg = <0x74>;


    shiphold-longpress = "ship";
    // shiphold-current = "low";
    // shiphold-hibernate-wakeup;

    npm2100_gpio: gpio-controller {
        compatible = "nordic,npm2100-gpio";
        gpio-controller;
        #gpio-cells = <2>;
        ngpios = <2>;
    };

    npm2100_regulators: regulators {
        compatible = "nordic,npm2100-regulator";

        npm2100_boost: BOOST {
            regulator-always-on;
            regulator-min-microvolt = <1800000>;
            regulator-max-microvolt = <3300000>;

            regulator-init-microvolt = <3300000>;
            regulator-init-microamp = <300000>;
            regulator-initial-mode = <(NPM2100_REG_OPER_AUTO | NPM2100_REG_FORCE_PASS)>;
            mode-gpios = <&npm2100_gpio 0 (GPIO_ACTIVE_LOW  | GPIO_PULL_DOWN | NPM2100_GPIO_DEBOUNCE_OFF)>;
        };


        npm2100_ldosw: LDOSW {
            regulator-min-microvolt = <800000>;
            regulator-max-microvolt = <3000000>;




            regulator-initial-mode = <(NPM2100_REG_OPER_ULP | NPM2100_REG_LDSW_EN)>;
            mode-gpios = <&npm2100_gpio 0 (GPIO_ACTIVE_HIGH  | GPIO_PULL_DOWN | NPM2100_GPIO_DEBOUNCE_OFF)>;
        };

    };

    npm2100_wdt: watchdog {
        compatible = "nordic,npm2100-wdt";
    };

    npm2100_vbat: vbat {
        compatible = "nordic,npm2100-vbat";
    };
};

Is it possible to configure break-to-wake mode using only the devicetree? I reviewed the driver itself and found options such as:

// shiphold-flags = <x>;
// shiphold-current = "low";
// shiphold-hibernate-wakeup;

Unfortunately, these do not seem to allow switching the mode itself.

If not, is there any example code available that enables it over I2C from the microcontroller? If I understand it correctly, I could use a callback from the SHPHLD pin and manually put the controller into break-to-wake mode.

Thank you in advance for any help. Perhaps someone has run into the same problem and managed to solve it.

Best regards,

Paweł

Menon · Accepted Answer

Hello, 
 s it possible to configure break-to-wake mode using only the devicetree? 
 Not fully, no, the application is still responsible for detecting the falling edge of the SHPHLD pin. For the Devicetree configuration, the recommendation is to: 
 shiphold-flags = <(GPIO_ACTIVE_HIGH | GPIO_PULL_UP)>;
 shiphold-longpress = "disable";
 shiphold-current = "weak";

GPIO_ACTIVE_HIGH instructs the PMIC to wake up on rising edge (when the short b/w SHPHLD and GND is removed) 
 GPIO_PULL_UP keeps the SHPHLD pin pulled up during the active state, so that the app can detect the falling edge on shortening 
 shiphold-longpress = "disable"; disables the "power off" functionality of the SHPHLD pin 
 shiphold-current = "weak"; can be adjusted according to the needs with "weak" meaning the lowest possible quiescent current during ship mode 
 
 As for the application, the best way would be to set up an interrupt on SHPHLD falling edge with a handler to enter ship mode (if there is a PMIC GPIO to spare) using the MFD driver. Otherwise the current SHPHLD state is available in the MAIN.STATUS register . 
 Kind Regards, 
 Abhijith

nPM2100 - break-to-wake

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