Periodic advertisement when APP_ADV_DURATION expires

Question

Hi, I am using ble_app_uart example for peripheral device and it will be powered by a 3.7 V battery. I need to use battery as long as possible. So I decided to make peripheral device advertise periodically. Since I need to use app_timer, System ON sleep mode works for me. I know that device doesn't advertise when APP_ADV_DURATION expires (assume it is not 0). I tried to restart advertise after APP_ADV_DURATION which triggers BLE_ADV_EVT_IDLE event. Also I disabled sleep_mode_enter() function in BLE_ADV_EVT_IDLE since it will put device in System OFF sleep mode. My timeout handler is like this: static void single_shot_timer_handler(void * p_context)
{
 uint32_t err_code;
 
 err_code = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST); 
 APP_ERROR_CHECK(err_code);
} 
 And I wanted to start timer in BLE_ADV_EVT_IDLE event like this: switch (ble_adv_evt)
 {
 case BLE_ADV_EVT_FAST:
 NRF_LOG_INFO("adv fast");
 err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING);
 APP_ERROR_CHECK(err_code);
 break;
 case BLE_ADV_EVT_IDLE:
 NRF_LOG_INFO("idle"); 
 err_code = app_timer_start(m_single_shot_timer_id, APP_TIMER_TICKS(20000), NULL);
 APP_ERROR_CHECK(err_code);
 //sleep_mode_enter();
 break; 
 I just wanted to advertise for 10 seconds and make it sleep for 20 seconds. I expected timer to start 20 seconds after BLE_ADV_EVT_IDLE. However, device advertises all the time. I mean when APP_ADV_DURATION expires, it doesn't stop advertising. 
 By the way APP_ADV_DURATION macro is 1000. And I use SDK 16 
 Could you please help me about it ? I will be very appreciated if you give me a suggestion. 
 Best Regards

Jørgen Holmefjord · Accepted Answer

It looks like the UART is causing the high current. I'm not sure if you need it when the device is not connected, but I could reduce the sleep current by adding this to the BLE_ADV_EVT_IDLE event: 
 app_uart_close();
*(volatile uint32_t *)0x40002FFC = 0;
*(volatile uint32_t *)0x40002FFC;
*(volatile uint32_t *)0x40002FFC = 1; 
 And then reinitialize it in the timer_handler: 
 uart_init(); 
 I then see about 6 uA average current during sleep:

Jørgen Holmefjord · Answer

The BLE_ADV_EVT_IDLE is only valid for the advertising role, it does not relate to connections (apart from the fact that a connection can only be established when the device is advertising). When a connection is established, the advertising will have to be restarted by the application. If a connection is established, you have to explicitly disconnect on one of the sides for the link to disconnect. If you want to disconnect at a specific time after the connection, you can do that with another timer. If you will transfer some data when a device connects, it may be simpler to do the disconnect once the data transfer is completed.

Periodic advertisement when APP_ADV_DURATION expires

Top Replies