GPIO - nRF9160 - on low battery (<3.0V), some GPIOs seems to stick/switch to output mode active

[Achim Kraus]

nRF9160, SICA B1A, mfw 1.3.7, NCS 3.1.0

I currently try to test the situation, when the battery gets drained "too much" and the voltage drops below 3.0V (e.g. 2.9V) on VDD1,VDD2 and VDD_GPIO.

The device has several outputs, but they behave different, even if I can't see the difference in the configuration nor usage. Some are on, some are off

I agree, that this is slightly "out of spec", but it's pretty nasty, because it potentially drains the battery further.

Are there any configs to prevent such "break down effects"?

[Achim Kraus]

Used overlay:

&pinctrl {

	uart0_default: uart0_default {
		group1 {
			psels = <NRF_PSEL(UART_TX, 0, 23)>,
				<NRF_PSEL(UART_RTS, 0, 25)>;
		};
		group2 {
			psels = <NRF_PSEL(UART_RX, 0, 22)>,
				<NRF_PSEL(UART_CTS, 0, 24)>;
			bias-pull-up;
		};
	};

	uart0_sleep: uart0_sleep {
		group1 {
			psels = <NRF_PSEL(UART_TX, 0, 23)>,
				<NRF_PSEL(UART_RX, 0, 22)>,
				<NRF_PSEL(UART_RTS, 0, 25)>,
				<NRF_PSEL(UART_CTS, 0, 24)>;
			low-power-enable;
		};
	};
};

/	{

	leds {
		led0: led_0 {
			gpios = <&gpio0 26 0>;
		};
		led1: led_1 {
			gpios = <&gpio0 27 0>;
		};
		led2: led_2 {
			gpios = <&gpio0 28 0>;
		};
	};

};

&uart1 {
	status = "disabled";
};

&i2c2 {
	status = "disabled";
};

&spi3 {
	status = "disabled";
};

GPIO for led0 and led1 are high, led2 is low. I don't see, that this is controlled by the app. 

[Øyvind]

Hello, 

Unfortunately, as you point out, as this is out of speck there is not much that can be done.

Kind regards,
Øyvind

[Achim Kraus]

Thanks.