sd_power_system_off is giving Gatt Connection Error instead of going in sleep

[AIRAM]

I am utilizing the nRF52811 with SDK version 16.00 for a project. However, I have encountered an issue related to the function sd_power_system_off, which is intended to put the device into a sleep mode. Instead of entering sleep mode, the function triggers an error labeled as "GATT_CONN_ERROR" on the nRF Connect mobile application.

I have taken the necessary steps to debug the issue, and through this process, I have confirmed that the sd_power_system_off function is indeed the source of the problem. To resolve this, I have conducted extensive research on various forums, but unfortunately, I have not yet identified a suitable solution to rectify this specific error.

In my pursuit of resolving the problem, I considered the potential influence of debugging on the deep sleep functionality. However, even after disconnecting the debugger and allowing the nRF52811 to run independently, the error persists unchanged.

For contextual clarity, I have provided a segment of the relevant code below, where I am implementing the deep sleep functionality:
Given the current situation, I am seeking assistance to address this issue and enable the intended sleep functionality on the nRF52811. Any insights, guidance, or recommendations that can be provided regarding this matter would be greatly appreciated. Thank you in advance for your help.

static void app_timer_callback(void* p_context)
{
    // Add your desired functionality here
}

static void timer_timeout_handler( void* p_context)
{ret_code_t err_code;

  UNUSED_PARAMETER(p_context);
nrf_timer_event_t event_type;

if(normalmode==false){
    timer_counter += 5000;
  NRF_LOG_DEBUG(" = timer_counter %d .",timer_counter );
  NRF_LOG_INFO(" = timer_counter %d.",timer_counter );
     
 if( timer_counter >= 120000)
   {

    
    NRF_LOG_DEBUG(" done;.");
  NRF_LOG_INFO(" done;.");

      app_timer_stop(m_app_timer);
 NRF_LOG_DEBUG(" cleared.");
  NRF_LOG_INFO(" cleared.");

// Configure the App Timer for the desired time interval (5 minutes)
interval_ms =  300 * 1000;  // 5 minutes
err_code = app_timer_start(m_app_timer, APP_TIMER_TICKS(interval_ms), NULL);
APP_ERROR_CHECK(err_code);
        
    NRF_LOG_DEBUG(" shifted.");
  NRF_LOG_INFO(" shifted.");
 }

    }

    else if (normalmode==true){
    if(f1<0.05 && f2<0.05 && f3<0.05 && f4<0.05){
    ds_counter+=5000;
    if(ds_counter>=5000){

  err_code = app_timer_stop(m_app_timer);
APP_ERROR_CHECK(err_code);
//sleep_mode_enter();
    // Go to system-off mode (this function will not return; wakeup will cause a reset).
    err_code = sd_power_system_off();
     if (err_code != NRF_SUCCESS) {
        NRF_LOG_WARNING("sd_power_system_off() failed, errCode=0x%x\n", err_code);
        return;
    //APP_ERROR_CHECK(err_code);

}}}}}
    

[Jared]

Hi,

First, I would like to point out, that if you put the nRF52811 into system off sleep while it's in a connection, then it's natural to expect the other side of the connection to result in a GATT_CONN_ERROR as the connection will be disrupted. Before you go to sleep, you should send a disconnect event, by disconnecting from the peer. 

Another important point is that nRF52811 will only emulate deep sleep when the debugger is connected, you need to disconnect the debugger for it to actually enter deep sleep.

 

regards

Jared 

[AIRAM]

Hi Jared,
Thank you so much for your time and help.
I have another question or favor to ask. Can you please explain how can I send a disconnect event by disconnecting from peer.

[Jared]

If you go to system off then you need to do intialize everything again, if you only disconnect then you can restart advertising by calling 

ble_advertising_start(),

How do you determine that the board doesn't wakeup?

regards

Jared

[AIRAM]

It doesn't advertise on sensing a GPIO low,
Okay i will try re advertising after system off mode

[AIRAM]

Same results, should i create a private ticket so that i can share my complete code with you and maybe then you can find the problem , I tried to find the key issue but I am not yet able to find root cause

[Jared]

Hi,

I can convert this case to a private case,

But first,

Have you made sure that the code reproduces the issue on a development kit?

regards

Jared 

[AIRAM]

No i didn't reproduce onto a DK, This code is written for nRF52811 but the development kit i have is nRF52832. 

It's okay, I will try to find the solution and will post here later iA, 
Thanks for your help all the way long.

Regards,

[AIRAM]

If the sleep function is called from an interrupt context, such as from the app timer callback, the program will never exit this while loop. This is because the Softdevice event that is supposed to clear the 'm_conn_handle' variable will become blocked. The simplest solution to this is to replace the while loop with a busy wait and hope the connection is successfully terminated after the delay.

LINK TO ANSWER

#include "nrf_delay.h"

static void sleep_mode_enter(void)
{ 
    ...
    (void) sd_ble_gap_disconnect(m_conn_handle, BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
    /* Wait for connection to be terminated*/
    nrf_delay_ms(100);
    ...