How to set tx_power using sd_ble_gap_tx_power_set() on nrf52832?

[dewal]

Hi Everyone,

I am working on nrf52832, I am using sdk15.0.0 ble_peripheral /ble_app_beacon as reference.

I want to set TX_POWER using sd_ble_gap_tx_power_set(BLE_GAP_TX_POWER_ROLE_ADV,m_adv_handle,RADIO_TXPOWER_TXPOWER_Pos4dBm);

  m_adv_handle = BLE_GAP_ADV_SET_HANDLE_NOT_SET;

when I called this function after the ble_advertising function,err_code return 12292.

actually i am not understood BLE_GAP_ADV_SET_HANDLE_NOT_SET=0xFF.

Initially tx_power set to 4dbm but when softdevice enable getting error (code stuck at blx ,r3).

I am also trying using NRF_RADIO->TX_POWER=RADIO_TXPOWER_TXPOWER_Pos4dBm;

Register initially set to 4dbm but after call ble_stack_init() it set to 0dbm.When you change txpower, you need to update this value of the advertising data, it doesn't get updated automatically by the softdevice. 

 I think I forgot some configuration in my code, Can you suggest a proper solution to see the changes in TXPOWER.

thanks.

[Einar Thorsrud]

Hi,

Error code 12292 = 0x3004 = BLE_ERROR_INVALID_ADV_HANDLE. The issue here is that you do not provide the correct advertising handle, which you get from the call to sd_ble_gap_adv_set_configure(). See this post.

[dewal]

thanks for reply, 

i am passing below parameter, 

err_code = sd_ble_gap_adv_set_configure(&(m_adv_handle), &m_adv_data, &m_adv_params);

Is this wrong?

I want to set TX_POWER using sd_ble_gap_tx_power_set(BLE_GAP_TX_POWER_ROLE_ADV,m_adv_handle,RADIO_TXPOWER_TXPOWER_Pos4dBm);

This function called after the advertising_start() .

Is this right way to set the tx_power ? 

[Einar Thorsrud]

The p_tx_power_level field points to the Tx power level field  in the advertising data. This is not directly related to the actual Tx power and does not set the Tx power for you. There is no problem specifying it here if you want the Tx power to be part of the advertising data, but this is just data. To adjust the physical Tx power, you must use sd_ble_gap_tx_power_set() as we have allready discussed.

[ande_dewal]

thanks for reply,

I tried using sd_ble_gap_tx_power_set()  but not set tx_power in my application. As our above discussion I called this function after the advertising_init() and before advertising_start(), still not set tx_power it always gives me 0dbm. 

advertising_init();
 
 err_code = sd_ble_gap_tx_power_set(  BLE_GAP_TX_POWER_ROLE_ADV, m_adv_handle,RADIO_TXPOWER_TXPOWER_Pos4dBm);
  APP_ERROR_CHECK(err_code);
 advertising_start();

please check this i am not understood ,what setting going wrong in my code. please help me for set tx_power for range . 

[Einar Thorsrud]

Hi,

ande_dewal said:

still not set tx_power it always gives me 0dbm. 

How do you know that it is 0 dBm? How have you measured it? Could it be that the problem here is that you read the tx_value field of the advertising or scan response packet and misinterprets that as the actual Tx power? As mention before, those are two separate things altogether. sd_ble_gap_tx_power_set() is used to change the physical Tx power. You can optionally include the Tx power in your scan reponse/advertising packet, but that is just data. Do you want to signal the Tx power? If so, you can add that here, but you still need to actually change it using sd_ble_gap_tx_power_set().

ande_dewal said:

please help me for set tx_power for range . 

You set tx_power using sd_ble_gap_tx_power_set() exactly as described in the API documentation.

[ande_dewal]

thanks for response,

At scanner, get_tx_power gives me 0dbm.also i checked at debugging on segger studio in RADIO->TX_POWER register . it always gives 0dbm. when i am using  below fun err_code = sd_ble_gap_tx_power_set(  BLE_GAP_TX_POWER_ROLE_ADV, m_adv_handle,RADIO_TXPOWER_TXPOWER_Pos4dBm);

now, I am not set through scan response .

[Einar Thorsrud]

I see. Then the problem here is this misunderstanding. The physical Tx power and the Tx power you signal are completely independent. To check the physical Tx power you need to measure. Alternatively, you could check the RSSI using nRF Connect. Note that there will typically be a lot of variation in these measurements unless you have proper equipment, but you could for instance check to see that you see a clear difference between when you call sd_ble_gap_tx_power_set with 0 and -40 or similar.