I have tried ble_app_uart_c project in SDk 9 , SDK 10 or SDK11 , but they have the same problem.
Problem is that slave(SDk 9,ble_app_uart) can send data to master(by terminal) , but master can't.
I did not modify the code that download form official website.
I remember that they can communicate each other before , so i confuse it.
Thanks.