Custom board based on nrf5340 CLAA not working after flashing the application

[Ke Li]

Hi,

I designed a custom PCB with the nrf5340 CLAA chip and am testing out the board. I want to flash a simple project of lighting up the on-board LED (the LED is connected to P1.07 in my board design). In nrf connect SDK in VS Code, I was able to create a custom board for nrf5340 QKAA (I was told this is fine for CLAA too), add the GPIO pin P1.07 in the DeviceTree, build the project without errors and flash the code to my board via JLink successfully. However, the LED is not lighted up. When I tried to debug, the process always stops at the step “Starting target CPU…” and won’t let me proceed.

I also tried to control the LED directly using JLink.exe via command line (I am using a windows machine because I encountered more issues on mac). I could connect to the chip in JLink. However, I was not able to write the values directly to the registers to light up the LED either. I wrote the values but when I checked the memory at the address, it was still 0. I checked the soldering of my board physically and they are all connected. I measured RESET and Power and they are both around 3.3V. Is there anything that you think I should try to solve this issue? Is there anything specific I should do to flash the code for the first time? (E.g. the chip is initially locked/protected so we can’t write to its memory directly for the first time?) Any advice would be appreciated. Thanks!

[Simonr]

Hi

These inductors were not part of the schematics you uploaded for our review, so it was assumed they were not present. Either way, thank you for confirming it's not the DCDC inductors causing this. It should be fine to test the application for the MDBT53V-DB-40 as long as you make sure you use the board files for this board when building the application. There are no obvious issues with the build/flash log. Make sure you're doing a Pristine build when you build with the DCDC regulators disabled to make sure you overwrite the existing application.

Best regards,

Simon

[Ke Li]

Hi Simon,

I am now able to enter the main function as shown below in debugging by setting CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y and 

# CONFIG_SOC_ENABLE_LFXO is not set because my board does not have an external 32kHz crystal. 

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

/* 1000 msec = 1 sec */
// #define SLEEP_TIME_MS   1000

/* The devicetree node identifier for the "led0" alias. */
#define LED0_NODE DT_ALIAS(led0)

/*
 * 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) {
    if (!device_is_ready(led.port)) {
        return 0;
    }
    gpio_pin_configure_dt(&led, GPIO_OUTPUT_ACTIVE);
    
    while (1) {  // Add infinite loop
        gpio_pin_set_dt(&led, 1);
        k_sleep(K_MSEC(1000));
        gpio_pin_set_dt(&led, 0);
        k_sleep(K_MSEC(1000));
    }
    
    return 0;
}

Now after building the application, when I debug, the process stops at the following lines of code in cmsis_gcc_m.h. When I hit continue, the on-board LED starts blinking as expected. However, when I just flash the same code instead of debugging, the code is not executed on the board. Do you have any idea why? Thanks!

/**
  \brief   Disable IRQ Interrupts
  \details Disables IRQ interrupts by setting special-purpose register PRIMASK.
           Can only be executed in Privileged modes.
 */
__STATIC_FORCEINLINE void __disable_irq(void)
{
  __ASM volatile ("cpsid i" : : : "memory");
}

Best,

Ke