https://devzone.nordicsemi.com/f/nordic-q-a/84043/uart-rx-data-loss-from-time-to-time-when-ble-communication-is-enabledHi, We have a device in production based on nrf52840 which uses UARTE to TX/RX data to/from a washing machine and in paralel communicates with a Phone App via BLE. SD: 132_3.0 | nRF5 SDK v12.3.0 Communicating with the machine via UART works withouten-USTelligent Community 13Wed, 26 Jan 2022 12:04:28 GMThttps://devzone.nordicsemi.com/thread/349743?ContentTypeID=1Wed, 26 Jan 2022 12:04:28 GMT137ad170-7792-4731-bb38-c0d22fbe4515:449bb245-8f53-4b56-ac2f-db0003429c4cVidar Berg<p>Hello,</p> <p>I would strongly recommend you upgrade to the latest SDK as version 12.x.x. does not have production level support for the nRF52840. See &quot;<span><a title="SDKs and SoftDevices " href="https://infocenter.nordicsemi.com/topic/comp_matrix_nrf52840/COMP/nrf52840/nRF52840_ic_rev_sdk_sd_comp_matrix.html?cp=4_0_3_2">SDKs and SoftDevices </a></span>&quot; for supported SDK and softdevice combinations.</p> <p>For reliable UART communication with Softdevice and no HWFC you have to use larger DMA buffers. I recommend using the <span><a title="Libuarte - advanced UARTE driver" href="https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/lib_libuarte.html?cp=8_1_3_28">Libuarte - advanced UARTE driver</a></span> for this.</p> [quote user=""]I tried to make buffer size 2 but it stopped receiving data...[/quote] <p>NRF_DRV_UART_EVT_RX_DONE is signaled after the receive buffer is full. So with this configuration, you will have to receive 2 bytes before the event gets raised.</p> <p>Best regards,</p> <p>Vidar</p><div style="clear:both;"></div>