i'm new in BLE, now i have project with nrf51822 and sdk 11.0.
in chip arm like STM, MPS or PIC, avr. when byte come, we have a flag set 1 to notice that there is one byte is comming., when nothing in RX buffer, this flag set 0.
so i want to know in nrf what things like this flag to notice one byte comming in RX uart
The UART will generate an RXDRDY event every time a new byte is moved to the RXD register. I recommend using the UART driver (nrf_drv_uart) to configure the UART and interrupts. Take a look at how this is done in e.g. the ble_app_uart example in the SDK.