How to limit BLE 5 range in nRF52840 to 5m in ble_app_uart?

[Devanshi1510]

Hi,

Board: nRF52840 PCA10056 Development kit

Keiluvision 5

SoftDevice : S140

nRF-SDK 15.2

SDK example code: ble_app_uart

Hi, I want to change the BLE range to 5 meters, so I tried this function as belows:

uint32_t err_code = sd_ble_gap_tx_power_set(BLE_GAP_TX_POWER_ROLE_ADV, m_advertising.adv_handle,-20);
APP_ERROR_CHECK(err_code);  

I got the change in range upto 9m but when I try to reduce it further to -40db I face issue while connecting again, I had to take my smartphone to the closest to the board to get connected again. This should not happen as it is getting connected and disconnected at  -20db properly. So, I think it should work like same at -40 db. Please help urgently and guide that what changes need to be done in the code. 

Thanks for your support

[run_ar]

I guess you could try to measure the RSSI you are getting at -40 dBm. I assume you are aware that the range will vary depending on the environment in the location you are in.  At what distance can you connect at -40dBm?