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.

[AIRAM]

static void sleep_mode_enter(void)
{
    uint32_t err_code = bsp_indication_set(BSP_INDICATE_IDLE);
    APP_ERROR_CHECK(err_code);

 nrf_gpio_cfg_input(18, NRF_GPIO_PIN_PULLUP);
nrf_gpio_cfg_sense_input(18, NRF_GPIO_PIN_PULLUP, NRF_GPIO_PIN_SENSE_LOW);

  //  printf("The system is going into deep sleep.\n");
sd_ble_gap_disconnect(m_conn_handle, BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);

 // Go to system-off mode (this function will not return; wakeup will cause a reset).
    err_code = sd_power_system_off();
    APP_ERROR_CHECK(err_code);

}



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){
   
    ds_counter+=5000;
    if(ds_counter>=5000){

  err_code = app_timer_stop(m_app_timer);
APP_ERROR_CHECK(err_code);
sleep_mode_enter(); 
}}

This is how i changed my code but still the results are same.

[Jared]

Hi,

I think you should wait for the BLE_GAP_EVT_DISCONNECTED event to be generated before going to sleep. Only then you can be sure that the Softdevice sent a disconnect event to the peer. 

BLE_GAP_EVT_DISCONNECTED will be generated in the ble_evt_handler(), for example from the Nordic UART Example:

This message sequence chart shows how disconnect looks like between you and the peer:

regards

Jared 

[AIRAM]

Hi Jared, 
Sorry I didn't get it clearly,
Do you mean to say I should use this instead of what i used to disconnect in my code?

Regards

Airam

[Jared]

Hi,

Before going to sleep, you should wait for BLE_GAP_EVT_DISCONNECTED to be generated after calling sd_power_system_off(). 

regards

Jared 

[AIRAM]

Hi Jared,
Results are still same, is there any solution of this problem?

[Jared]

Hi,

Can you show me how you implemented it?

regards

Jared