Setting advertising transmission power

[Ridhi]

i have nrf52832 sdk vr 17.0.2. i want to set transmission power of advertising packet. pls assist

[Karl Ylvisaker]

Hello,

You can set this using the sd_ble_gap_tx_power_set function directly.
As mentioned in the function API Reference you will need to enable include_tx_power for it to be included in your advertising packet.

Best regards,
Karl

[Ridhi]

 */
static void advertising_init(){
    ret_code_t             err_code;
    ble_advertising_init_t init;

    memset(&init, 0, sizeof(init));

    init.advdata.name_type                = BLE_ADVDATA_FULL_NAME;
    init.advdata.include_appearance       = true;
    init.advdata.flags                    = BLE_GAP_ADV_FLAGS_LE_ONLY_LIMITED_DISC_MODE;
   
		init.srdata.uuids_more_available.uuid_cnt=sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
		init.srdata.uuids_more_available.p_uuids =m_adv_uuids;
    init.config.ble_adv_whitelist_enabled = false;
    init.config.ble_adv_fast_enabled      = true;
    init.config.ble_adv_fast_interval     = APP_ADV_INTERVAL;
    init.config.ble_adv_fast_timeout      = APP_ADV_DURATION;
    
    init.evt_handler = on_adv_evt;

    err_code = ble_advertising_init(&m_advertising, &init);
    APP_ERROR_CHECK(err_code);
    uint32_t err_code = sd_ble_gap_tx_power_set(BLE_GAP_TX_POWER_ROLE_ADV, m_advertising.adv_handle, 4); 
    APP_ERROR_CHECK(err_code);
    ble_advertising_conn_cfg_tag_set(&m_advertising, APP_BLE_CONN_CFG_TAG);
		
		
		
		
		
}

is it how shall it work?? i have added

  uint32_t err_code = sd_ble_gap_tx_power_set(BLE_GAP_TX_POWER_ROLE_ADV, m_advertising.adv_handle, 4);
APP_ERROR_CHECK(err_code);

pls chek

[Karl Ylvisaker]

Yes, thought you do not need to have the type declaration there since you've already declared it at the beginning of your function.
Are you not seeing an increase in the RSSI when you've added this line?

Best regards,
Karl

[Ridhi]

yes, i found that increasing power in adv increases the RSSI. 

Kindly tell by default what is the power used if i dont add the sd_ble_gap_tx_power_set(). 

Also, what is the default PHY used

[Karl Ylvisaker]

Ridhi said:

yes, i found that increasing power in adv increases the RSSI. 

Great, I'm happy to hear that it worked as expected.

Ridhi said:

Kindly tell by default what is the power used if i dont add the sd_ble_gap_tx_power_set(). 

Also, what is the default PHY used

The default txpower is +0, and the BLE advertising library default to using 1M PHY if no other phy is specified for the advertising mode, this happens in the following section of ble_advertising_start

..
    // Use 1MBIT as primary phy if no phy was selected.
    if (phy_is_valid(&p_advertising->adv_modes_config.ble_adv_primary_phy))
    {
        p_advertising->adv_params.primary_phy = p_advertising->adv_modes_config.ble_adv_primary_phy;
    }
    else
    {
        p_advertising->adv_params.primary_phy = BLE_GAP_PHY_1MBPS;
    }
..

Best regards,
Karl

[Ridhi]

thnku Karl,

wud like to know that min how much time an advertising event takes. Like  adv interval can range from 20 ms to 10.24s. i want to know min an event take how much time 

[Karl Ylvisaker]

I am not entirely sure what you are asking about. Are you asking about how long it takes to perform a single advertising? If so, this will depend on the advertising payload and configuration. You could use the Online Power Profiler to see the effects of different configurations on the advertising length. It gives a good estimate for how long each advertising would take.

Please also keep in mind that a random 0 - 10 ms delay is added before every advertising, as specified in the BLE specification. That means that even if you have set the advertising interval to be 100 ms, it could be anything between 100 and 110 ms that passes before the next advertising is sent. This delay is added for you by the SoftDevice.

Best regards,
Karl