Changes in the DTS file don't apply after DFU

[Priyesh Shahi]

I have an array of LEDs on my custom board. One of the LEDs is set on a UART0 RTS pin, which is GPIO(0,5), and we are using ground as common. To avoid any conflicts, I disabled the UART0 node in my overlay file, but this LED still glows before any other LED.

&pwm0 {
	status = "okay";
};

&spi1 {
	status = "disabled";
};

&spi3 {
	status = "disabled";
};


&i2c1 {
	status = "disabled";
};

&pwm1 {
	status = "okay";
	pinctrl-0 = <&pwm1_default>;
	pinctrl-1 = <&pwm1_sleep>;
	pinctrl-names = "default", "sleep";
};

&pwm2 {
	status = "okay";
	pinctrl-0 = <&pwm2_default>;
	pinctrl-1 = <&pwm2_sleep>;
	pinctrl-names = "default", "sleep";
};

&pwm3 {
	status = "okay";
	pinctrl-0 = <&pwm3_default>;
	pinctrl-1 = <&pwm3_sleep>;
	pinctrl-names = "default", "sleep";
};

&uart1 {
	status = "disabled";
};

&arduino_header {
	gpio-map = <0 0 &gpio0 3 0>,
	           <1 0 &gpio0 4 0>,
	           <2 0 &gpio0 28 0>,
	           <3 0 &gpio0 29 0>,
	           <4 0 &gpio0 30 0>,
	           <5 0 &gpio0 31 0>,
	           <6 0 &gpio1 1 0>,
	           <7 0 &gpio1 2 0>,
	           <8 0 &gpio1 3 0>,
	           <9 0 &gpio1 4 0>,
	           <10 0 &gpio1 5 0>,
	           <11 0 &gpio1 6 0>,
	           <12 0 &gpio1 7 0>,
	           <13 0 &gpio1 8 0>,
	           <14 0 &gpio1 10 0>,
	           <15 0 &gpio1 11 0>,
	           <16 0 &gpio1 12 0>,
	           <17 0 &gpio1 13 0>,
	           <18 0 &gpio1 14 0>,
	           <19 0 &gpio1 15 0>,
	           <20 0 &gpio0 26 0>,
	           <21 0 &gpio0 27 0>;
};


&pinctrl {

	uart0_default: uart0_default {
		group1 {
			psels = <NRF_PSEL(UART_TX, 0, 6)>;
					// <NRF_PSEL(UART_RTS, 1, 12)>;
		};
		group2 {
			psels = <NRF_PSEL(UART_RX, 0, 8)>,
					<NRF_PSEL(UART_CTS, 0, 7)>;
			bias-pull-up;
		};
	};

	uart0_sleep: uart0_sleep {
		group1 {
			psels = <NRF_PSEL(UART_TX, 0, 6)>,
			        <NRF_PSEL(UART_RX, 0, 8)>,
			        // <NRF_PSEL(UART_RTS, 1, 12)>,
			        <NRF_PSEL(UART_CTS, 0, 7)>;
			low-power-enable;
		};
	};

	pwm0_default: pwm0_default {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 0, 13)>,
			        <NRF_PSEL(PWM_OUT1, 1, 6)>,
			        <NRF_PSEL(PWM_OUT2, 1, 5)>,
			        <NRF_PSEL(PWM_OUT3, 1, 4)>;
			nordic,invert;
		};
	};

	pwm0_sleep: pwm0_sleep {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 0, 13)>,
			        <NRF_PSEL(PWM_OUT1, 1, 6)>,
			        <NRF_PSEL(PWM_OUT2, 1, 5)>,
			        <NRF_PSEL(PWM_OUT3, 1, 4)>;
			low-power-enable;
		};
	};

	pwm1_default: pwm1_default {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 0, 24)>,
			        <NRF_PSEL(PWM_OUT1, 1, 9)>,
			        <NRF_PSEL(PWM_OUT2, 1, 8)>,
			        <NRF_PSEL(PWM_OUT3, 0, 5)>;
			nordic,invert;
		};
	};

	pwm1_sleep: pwm1_sleep {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 0, 24)>,
			        <NRF_PSEL(PWM_OUT1, 1, 9)>,
			        <NRF_PSEL(PWM_OUT2, 1, 8)>,
			        <NRF_PSEL(PWM_OUT3, 0, 5)>;
			low-power-enable;
		};
	};

	pwm2_default: pwm2_default {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 0, 2)>,
			        <NRF_PSEL(PWM_OUT1, 0, 29)>,
			        <NRF_PSEL(PWM_OUT2, 1, 15)>,
			        <NRF_PSEL(PWM_OUT3, 0, 28)>;
			nordic,invert;
		};
	};

	pwm2_sleep: pwm2_sleep {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 0, 2)>,
			        <NRF_PSEL(PWM_OUT1, 0, 29)>,
			        <NRF_PSEL(PWM_OUT2, 1, 15)>,
			        <NRF_PSEL(PWM_OUT3, 0, 28)>;
			low-power-enable;
		};
	};

	pwm3_default: pwm3_default {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 1, 13)>,
					<NRF_PSEL(PWM_OUT1, 1, 10)>;
			nordic,invert;
		};
	};

	pwm3_sleep: pwm3_sleep {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 1, 13)>,
					<NRF_PSEL(PWM_OUT1, 1, 10)>;
			low-power-enable;
		};
	};

	i2c0_default: i2c0_default {
		group1 {
			psels = <NRF_PSEL(TWIM_SDA, 0, 30)>,
					<NRF_PSEL(TWIM_SCL, 0, 31)>;
		};
	};

	i2c0_sleep: i2c0_sleep {
		group1 {
			psels = <NRF_PSEL(TWIM_SDA, 0, 30)>,
					<NRF_PSEL(TWIM_SCL, 0, 31)>;
			low-power-enable;
		};
	};
};



&i2c0_default {
	group1 {
		bias-pull-up;
		psels = <NRF_PSEL(TWIM_SDA, 0, 30)>, <NRF_PSEL(TWIM_SCL, 0, 31)>;
	};
};

/ {

	pwmleds {
		compatible = "pwm-leds";
		pwm_led1: pwm_led_1 {
			pwms = <&pwm0 1 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		pwm_led2: pwm_led_2 {
			pwms = <&pwm0 2 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		pwm_led3: pwm_led_3 {
			pwms = <&pwm0 3 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		pwm_led4: pwm_led_4 {
			pwms = <&pwm1 0 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		pwm_led5: pwm_led_5 {
			pwms = <&pwm1 1 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		pwm_led6: pwm_led_6 {
			pwms = <&pwm1 2 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		pwm_led7: pwm_led_7 {
			pwms = <&pwm1 3 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		pwm_led8: pwm_led_8 {
			pwms = <&pwm2 0 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		pwm_led9: pwm_led_9 {
			pwms = <&pwm2 1 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		pwm_led10: pwm_led_10 {
			pwms = <&pwm2 2 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		pwm_led11: pwm_led_11 {
			pwms = <&pwm2 3 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		pwm_led12: pwm_led_12 {
			pwms = <&pwm3 0 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		pwm_led13: pwm_led_13 {
			pwms = <&pwm3 1 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
	};

	buttons {
		compatible = "gpio-keys";
		button4: button_4 {
			gpios = <&gpio0 27 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
			label = "Push button switch 4";
			zephyr,code = <INPUT_KEY_4>;
		};

		button5: button_5 {
			gpios = <&gpio1 2 (GPIO_PULL_DOWN | GPIO_ACTIVE_HIGH)>;
			label = "Push button switch 5";
			zephyr,code = <INPUT_KEY_5>;
		};
	};

	/* These aliases are provided for compatibility with samples */
	aliases {
		pwm-led1 = &pwm_led1;
		pwm-led2 = &pwm_led2;
		pwm-led3 = &pwm_led3;
		pwm-led4 = &pwm_led4;
		pwm-led5 = &pwm_led5;
		pwm-led6 = &pwm_led6;
		pwm-led7 = &pwm_led7;
		pwm-led8 = &pwm_led8;
		pwm-led9 = &pwm_led9;
		pwm-led10 = &pwm_led10;
		pwm-led11 = &pwm_led11;
		pwm-led12 = &pwm_led12;
		pwm-led13 = &pwm_led13;
		die-temp0 = &temp;
		sw4 = &button4;
		sw5 = &button5;
	};
};

Also, when I am debugging my code, even before I run any code or command, this sequence happens. To solve this pin issue, I commented out the RTS pin configuration line in the pin-ctrl.dts file.

When I flashed it on my device, the problem got solved. However, when I used DFU to flash the same firmware on another device, the firmware updates successfully, but the problem remains the same. Can you help me with another solution to solve this problem? I am using inverse logic on the LED array to glow them.

What should I change in the overlay, in DFU, or elsewhere?

[Menon]

Hello,

When I flashed it on my device, the problem got solved. However, when I used DFU to flash the same firmware on another device, the firmware updates successfully, but the problem remains the same.

Could you tell me which two devices are mentioned here? Specifically, which chip or development kit (DK) is referred to as my device, and which one is the other device? Could you also share the SDK version on which the application is built?

Kind Regards,

Abhijith

[Priyesh Shahi]

Hello Abhijith,

Thank you for your query.

I am using the nRF52840 DK board for evaluation purposes. The custom board we've designed also uses the nRF52840 SoC. The primary difference between the DK board and our custom board is in the power configuration: the DK board uses VCC as the common reference, while our custom board uses ground as the common reference.

To clarify the devices mentioned:

• My device: This refers to our custom board with the nRF52840 SoC and ground as the common reference.
• The other device: This refers to the nRF52840 DK board used for initial evaluation.

Regarding the SDK version, the application is built on NCS version 2.5.1.

Please let me know if you need any more information or assistance.

Kind Regards,

Priyesh

[Menon]

Hello Priyesh,

I apologize for the delay in getting back to you. It’s summer vacation here in Norway, and the workload is a bit high due to being understaffed.

Regarding your issue, it might be related to the initial state or configuration of the pin at startup, even before the UART0 node is disabled or any code is executed. This can happen when pins are configured by default as part of the boot process or have default states that cause unintended behavior. I reviewed the device tree, and I can see that UART0 is already disabled, which is correct.

Assuming you are using MCUboot as the bootloader, I recommend creating an `mcuboot.overlay` file (`child_image-->mcuboot.overlay`) and configuring the UART0 RTS pin typically as an output, setting it low to prevent the LED from glowing. Let me know if this approach makes any difference.

Kind regards,

Abhijith

[Priyesh Shahi]

Hello Abhijith,

I apologize for the delay in getting back to you.

I appreciate your suggestion regarding the mcuboot.overlay file. I'm pleased to inform you that your solution works effectively and resolves the issue. It is indeed a better approach compared to the temporary solution I had found earlier.

Thank you for your assistance.

Kind regards,

Priyesh