The default serial port overwrite issue of NRF54L15

[yxh_kk]

I'm a new software developer and I'm not a native English speaker. I ask questions through a translator now, the description might not be clear.

I am currently working on the NRF54L15.  In my overlay file, I disabled UART20 and defined P1.05 as an enable pin for a peripheral.  However, when the system powers on, there is still a high-pull operation on P1.05, just like for UART.  I found that this operation occurs before the main function is executed because I added a delay at the first line of the main function and observed that the initial state of P1.05 was still high.  After entering the main function, I can control the high and low levels of P1.05 as expected.  I cannot allow P1.05 to be pulled high at the initial power-on because when the battery is low and charging, it will reset the NRF54L15, and the high pull on EN will drive a large load, preventing me from charging.  I discovered that the high pull is bound to UART20, but I don't understand why it still occurs at the initial state of the program even though I overwrote it.

thanks

dts：

&uart20 {
status = "disabled";
};

&spi21 {
compatible = "nordic,nrf-spim";
status = "okay";

pinctrl-0 = <&spi21_default>;
pinctrl-1 = <&spi21_sleep>;
pinctrl-names = "default", "sleep";

cs-gpios = <&gpio1 11 GPIO_ACTIVE_LOW>;
};

&i2c22 {
compatible = "nordic,nrf-twim";
#address-cells = <1>;
#size-cells = <0>;
reg = <0xc8000 0x1000>;
interrupts = <200 NRF_DEFAULT_IRQ_PRIORITY>;
easydma-maxcnt-bits = <16>;
status = "okay";
zephyr,pm-device-runtime-auto;
clock-frequency = <100000>;

pinctrl-0 = <&i2c22_default>;
pinctrl-1 = <&i2c22_sleep>;
pinctrl-names = "default", "sleep";

bct24157l: bct24157l@2d {
compatible = "bosch,bct24157l";
reg = <0x2d>;
status = "okay";
};
};

&pinctrl {
spi21_default: spi21_default {
group1 {
psels = <NRF_PSEL(SPIM_SCK, 1, 10)>,
<NRF_PSEL(SPIM_MOSI, 1, 14)>,
<NRF_PSEL(SPIM_MISO, 1, 9)>;
};
};

spi21_sleep: spi21_sleep {
group1 {
psels = <NRF_PSEL(SPIM_SCK, 1, 10)>,
<NRF_PSEL(SPIM_MOSI, 1, 14)>,
<NRF_PSEL(SPIM_MISO, 1, 9)>;
};
};

i2c22_default: i2c22_default {
group1 {
psels = <NRF_PSEL(TWIM_SDA, 1, 6)>,
<NRF_PSEL(TWIM_SCL, 1, 3)>;
};
bias-pull-up;
drive-push-pull;
slew-rate-slow;
};

i2c22_sleep: i2c22_sleep {
group1 {
psels = <NRF_PSEL(TWIM_SDA, 1, 6)>,
<NRF_PSEL(TWIM_SCL, 1, 3)>;
};
bias-pull-up;
low-power-enable;
};
};

/delete-node/ &button1;
/delete-node/ &button2;
/delete-node/ &{/pin-controller/pwm20_default/group1/};
/delete-node/ &{/pin-controller/pwm20_sleep/group1/};

/delete-node/ &{/pin-controller/spi00_default/group1/};
/delete-node/ &{/pin-controller/spi00_sleep/group1/};

&spi00 {
/delete-property/ cs-gpios;
};

&gpio1 {
status = "okay";
};

&led0 {
gpios = <&gpio1 12 GPIO_ACTIVE_HIGH>;
label = "Start GPIO";
};

&led2 {
gpios = <&gpio1 13 GPIO_ACTIVE_LOW>;
label = "Reset GPIO";
};

&led3 {
gpios = <&gpio2 10 GPIO_ACTIVE_HIGH>;
label = "Charge LED";
};

&button0 {
gpios = <&gpio1 7 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
label = "Power Save Button";
zephyr,code = <INPUT_KEY_0>;
};

&uart30 {
status = "okay";
current-speed = <115200>;
pinctrl-0 = <&uart30_default>;
pinctrl-1 = <&uart30_sleep>;
pinctrl-names = "default", "sleep";
};

&pinctrl {
uart30_default: uart30_default {
group1 {
psels = <NRF_PSEL(UART_TX, 0, 0)>,
<NRF_PSEL(UART_RX, 0, 1)>;
};
};

uart30_sleep: uart30_sleep {
group1 {
psels = <NRF_PSEL(UART_TX, 0, 0)>,
<NRF_PSEL(UART_RX, 0, 1)>;
low-power-enable;
};
};
};

/ {
chosen {
zephyr,console = &uart30;
zephyr,shell-uart = &uart30;
zephyr,uart-mcumgr = &uart30;
zephyr,bt-mon-uart = &uart30;
zephyr,bt-c2h-uart = &uart30;
};
};

&led1 {
gpios = <&gpio2 9 0>;
};

/ {
ads1299_en_gpio {
compatible = "gpio-keys";
en_gpio {
gpios = <&gpio1 5 GPIO_ACTIVE_HIGH>;
label = "ADS1299 EN GPIO";
};
};
};

/ {
charge_detect_pins {
compatible = "gpio-keys";
button_0 {
gpios = <&gpio2 0 GPIO_ACTIVE_HIGH>;
label = "Charge Detect";
};
button_1 {
gpios = <&gpio2 1 GPIO_ACTIVE_HIGH>;
label = "Charge Status";
};
};
};

/ {
ads1299_drdy_gpio {
compatible = "gpio-keys";
drdy_pin {
gpios = <&gpio1 4 GPIO_ACTIVE_LOW>;
label = "ADS1299 DRDY";
};
};
};

[Edvin]

Hello,

Are you using a DK to measure the behavior of P1.05? If so, what you are seeing is not the nRF54l15 pulling it high. It is the debugger that the UART is connected to that is pulling it up. Luckily, it is easy to disable, at least if your DK is fairly new. If you download nRF Connect for Desktop, and install the Board Configurator, you can disable the debuggers UART0 and UART0 HWFC:

If you have an older version of the DK, you may need to cut some, and short some other solder bridges. The numbers for them should be mentioned on the back of the DK.

Best regards,

Edvin

[yxh_kk]

NO，not using a DK to measure the behavior of P1.05.it‘s my new board designed by myself

[Edvin]

Oh, I see. I jumped to conclusion. Will I be able to reproduce what you are seeing on a DK perhaps? Is it possible to upload your application, so that I can try to run it locally, and see if I can reproduce the same behavior? And if you upload your project, please include the build folder, so that I can check that everything has been set properly after your application was compiled.

Best regards,

Edvin