STM32 Application Prevents ST-LINK connection

[Maldus512]

Hello everyone,
I'm developing a Zephyr application for a custom stm32413 board. I've successfully setup the project and confirmed it works, but I'm facing an issue with the flashing procedure.
Basically the west flash commands only works if the application itself isn't running on the board. To program it successfully I have to enter the ROM bootloader.

For reference, this is the code:

main.c

#include <stdio.h>
#include <zephyr/kernel.h>
#include <zephyr/drivers/gpio.h>
#include <zephyr/logging/log.h>


LOG_MODULE_REGISTER(main);

#define SLEEP_TIME_MS 500                /* 1000 msec = 1 sec */
#define LED0_NODE     DT_ALIAS(heartbit) /* The devicetree node identifier for the "led0" alias. */

/*
 * A build error on this line means your board is unsupported.
 * See the sample documentation for information on how to fix this.
 */
static const struct gpio_dt_spec led = GPIO_DT_SPEC_GET(LED0_NODE, gpios);

int main(void) {
    int  ret;
    bool led_state = true;

    if (!gpio_is_ready_dt(&led)) {
        return 0;
    }

    ret = gpio_pin_configure_dt(&led, GPIO_OUTPUT_ACTIVE);
    if (ret < 0) {
        return 0;
    }

    for (;;) {
        ret = gpio_pin_toggle_dt(&led);
        if (ret < 0) {
            return 0;
        }

        led_state = !led_state;
        //printk("LED state: %s\n", led_state ? "ON" : "OFF");
        k_msleep(SLEEP_TIME_MS);
    }
    return 0;
}

prj.conf

# Enable GPIO ports A, B, C, D, E, F, G, H
CONFIG_GPIO=y

# Debug
CONFIG_DEBUG=y

board.dts

/*
 * Copyright (c) 2024 STMicroelectronics
 *
 * SPDX-License-Identifier: Apache-2.0
 */

/dts-v1/;
#include <st/f4/stm32f413Xg.dtsi>
#include <st/f4/stm32f413v(g-h)tx-pinctrl.dtsi>
#include "arduino_r3_connector.dtsi"
#include <zephyr/dt-bindings/input/input-event-codes.h>

/ {
	model = "HSW paperone board";
	//compatible = "st,stm32f413";

	chosen {
		//zephyr,console = &usart1;
		//zephyr,shell-uart = &usart1;
		zephyr,sram = &sram0;
		zephyr,flash = &flash0;
	};

	leds {
		compatible = "gpio-leds";
		heartbit_led: led_0 {
			gpios = <&gpiob 10 GPIO_ACTIVE_HIGH>;
			label = "User LED";
		};
	};

	aliases {
		heartbit = &heartbit_led;
	};
};

&clk_lsi {
	status = "okay";
};

&clk_hse {
	//hse-bypass;
	clock-frequency = <DT_FREQ_M(8)>; /* STLink 8MHz clock */
	status = "okay";
};

&rcc {
	//clocks = <&pll>;
	clocks = <&clk_hse>;
	//clock-frequency = <DT_FREQ_M(100)>;
	clock-frequency = <DT_FREQ_M(8)>;
	ahb-prescaler = <1>;
	apb1-prescaler = <1>;
	apb2-prescaler = <1>;
};

&rtc {
	clocks = <&rcc STM32_CLOCK_BUS_APB1 0x10000000>,
		 <&rcc STM32_SRC_LSI RTC_SEL(2)>;
	status = "okay";
};

I'm using an official ST-LINK v2. The output is as follows:

$ west flash
The module for runner "nios2" could not be imported (No module named 'runners.nios2'). This most likely means it is not handling its dependencies properly. Please report this to the zephyr developers.
-- west flash: rebuilding
ninja: no work to do.
-- west flash: using runner stm32cubeprogrammer
      -------------------------------------------------------------------
                        STM32CubeProgrammer v2.19.0                  
      -------------------------------------------------------------------

ST-LINK SN  : 38FF6E06304E4B3039452143
ST-LINK FW  : V2J29S7
Board       : --
Voltage     : 1.71V
SWD freq    : 4000 KHz
Connect mode: Under Reset
Reset mode  : Hardware reset
Device ID   : 0x463
Revision ID : Rev A
Device name : STM32F413/F423
Flash size  : 1 MBytes
Device type : MCU
Device CPU  : Cortex-M4
BL Version  : 0x90

Opening and parsing file: zephyr.hex


Memory Programming ...
  File          : zephyr.hex
  Size          : 15.21 KB 
  Address       : 0x08000000 



Erasing memory corresponding to sector 0:
Erasing internal memory sector 0
Download in Progress:
[==================================================] 100% 

File download complete
Time elapsed during download operation: 00:00:00.891

RUNNING Program ... 
  Address:      : 0x8000000
Application is running, Please Hold on...
Start operation achieved successfully

# Second flash attempt
$ west flash
The module for runner "nios2" could not be imported (No module named 'runners.nios2'). This most likely means it is not handling its dependencies properly. Please report this to the zephyr developers.
-- west flash: rebuilding
ninja: no work to do.
-- west flash: using runner stm32cubeprogrammer
      -------------------------------------------------------------------
                        STM32CubeProgrammer v2.19.0                  
      -------------------------------------------------------------------

ST-LINK SN  : 38FF6E06304E4B3039452143
ST-LINK FW  : V2J29S7
Board       : --
Voltage     : 1.71V
Error: Unable to get core ID
Error: ST-LINK error (DEV_TARGET_CMD_ERR)
FATAL ERROR: command exited with status 1: /home/maldus/Local/bin/STM32_Programmer_CLI --connect 'port=swd reset=HWrst' --download /home/maldus/Projects/Rotondi/cassa-rotondi/build/zephyr/zephyr.hex --start

The error message lead me to this discussion which then pointed me to the CONFIG_DEBUG option, with no luck.
If I remove the call to k_msleep the programming command works every time, so it appears to be an issue with whatever sleep mode Zephyr is entering. How can I configure the project to keep the debug module alive enough to respond to subsequent requests?

[TK5090]

Are you able to flash with STM32CubeProgrammer v2.19.0 directly without using west?