Power management (pwr_mgmt) + systick causes board hangup

[RoyCreemers]

We are using a NRF52840 chip (SDK 15.3) in an application  and are having issues with the startup of the board. I managed to create an example application where I integrate the systick with power management.

#include <stdbool.h>
#include <stdint.h>
#include "nrf_drv_systick.h"
#include "boards.h"
#include "nrf_pwr_mgmt.h"

static int cnt = 0;
void SysTick_Handler(void)
{
    if (cnt % 1000 == 0)
      bsp_board_led_invert(0);

    cnt++;
}

int main(void)
{
  SysTick_Config(SystemCoreClock/1000 );
  bsp_board_init(BSP_INIT_LEDS);
  nrf_pwr_mgmt_init();
  
  while (true)
  {
    //nrf_pwr_mgmt_run();
  }
}

The example works fine and blinks an LED of the development kit once a second. 

However, once I uncomment 'nrf_pwr_mgmt_run' the board does not power up anymore after I have toggled the complete power (by removing/attaching the USB connector). Pressing the reset button only does not cause problems, and the board works as expected. 

Am I missing anything here?

[haakonsh]

Hmm, maybe SystemCoreClock/1000 gets converted to a float and messes of the systick configuration.
 

However, once I uncomment 'nrf_pwr_mgmt_run' the board does not power up anymore after I have toggled the complete power (by removing/attaching the USB connector).

 Can you share some details on "board does not power up", like what are your exact observations?

[oguzcan oguz]

Once I program this example, the LED on the board blinks with a frequency of once a second (systick is 1000 Hz). Once I reset it by pressing the reset button, it starts blinking with the same rate.

Once I reset the board by removing the USB connection, nothing happens anymore.

[haakonsh]

Are you powering the board by the nRF52840's USB connector?
If so do the LED's start blinking when you re-connect it?

[RoyCreemers]

Let me phrase it correctly: I reset the board by re-applying the USB connection. After the board is reconnected, the LED does not start blinking anymore. I'm powering the board by USB 

[haakonsh]

The USB is a reset source if it triggers a Power-on reset or a Wakeup from System OFF mode reset.

A Power-on reset will only trigger if the USB is the power supply.

A wake-up from System Off reset will only trigger if the system is in System Off and a debugger is not attached. 

[RoyCreemers]

I'm not sure I understand where you are going.... I know a power-on reset is triggered, question is why the LED does not start blinking after this reset.

[haakonsh]

How do you know that a power-on reset is triggered and that the MCU has booted?

[RoyCreemers]

Why would a power-on reset NOT be triggered? I'm powering the board. Please check with the initial question, the issue starts occuring once I do a call to 'nrf_pwr_mgmt_run'

[haakonsh]

Oh, now I know. You're shutting down the CPU with nrf_pwr_mgmt_run(), and SysTick only runs when the CPU is on.