Can we use UART in a ble interrupt ?

Question

I have a ble central device. Sending commands to UART in main() works well. Sending in on_ble_evt() doesn't work (only the first char).
But I see in your examples that you use UART in ble_nus_c_evt_handler() 
 So when can we use UART and when can we not use it ? I have problems understanding what we can do and when : I thought the BLE code is driven by interrupts and we should do only very quick things there, to be sure we finish doing them before the next BLE interrupt 
 Thanks

Pavan kumar · Accepted Answer

I guess first you need to make sure weather you are using a uart_fifo.c or simple_uart generally simple_uart will return this problem like just printing the first char