https://devzone.nordicsemi.com/f/nordic-q-a/51256/set-tx-power-nrf52840-pca10059-sdk-15-3-s140-program-hangs-at-app_error-_checkGood day I converted a Central UART example. I thought I would experiment with the &quot;sd_ble_gap_tx_power_set()&quot; function to see how it works. When I include the following My program just hangs at APP_ERROR_CHECK. No error code or assert. Ifen-USTelligent Community 13Thu, 22 Aug 2019 08:19:54 GMThttps://devzone.nordicsemi.com/thread/205469?ContentTypeID=1Thu, 22 Aug 2019 08:19:54 GMT137ad170-7792-4731-bb38-c0d22fbe4515:42d71bbc-5b5d-4fc6-98b7-a268b09e677aSigurd[quote userid="74893" url="~/f/nordic-q-a/51256/set-tx-power-nrf52840-pca10059-sdk-15-3-s140-program-hangs-at-app_error-_check"]I set a breakpoint at APP_ERROR_CHECK&nbsp; err_code =0x00000002[/quote] <p>Error code 2 is <a href="https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s140.api.v6.1.1/group__nrf__error.html?cp=3_4_3_1_2_0_7_17#ga9a2af1a322a5dfb3bdb69e2aacd3bc27">NRF_ERROR_SOFTDEVICE_NOT_ENABLED</a>. Make sure that you set TX power after the softdevice is enabled.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/205379?ContentTypeID=1Wed, 21 Aug 2019 15:08:32 GMT137ad170-7792-4731-bb38-c0d22fbe4515:b8dea37e-2070-4a34-83ca-8f9f4dc52752melt<p>thanks, Jimmy, will have a look.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/205368?ContentTypeID=1Wed, 21 Aug 2019 14:46:57 GMT137ad170-7792-4731-bb38-c0d22fbe4515:f828262e-8e24-4eeb-832d-4b6c10ede3b8Jimmy Wong<p>HI,<br /><br />you can refer to my example (<a href="https://github.com/jimmywong2003/nrf52-ble5-long-range-demo">https://github.com/jimmywong2003/nrf52-ble5-long-range-demo</a>).<br /><br />I set the TX power on both peripheral and central role.</p><div style="clear:both;"></div>