1. Function description

    Bluetooth BLE data transmission service (rdts) example, using 128bit UUID. 
    After the BLE host connects to the device, the downlink data will be transparently 
    transmitted to USART1, and the data received by USART1 will be transparently 
    transmitted to the BLE host.
    This example will allow connect to 3 master at the same time. The first byte will
    be the connection to send if it in 0x00 to 0x02, otherwise send the data to all connection.

2. Operating environment
    Software development environment: KEIL MDK-ARM V5.30.0.0
    Hardware environment: Developed based on the development board N32WB031_STB

3. Instructions

    System configuration;
        1. Clock source: HSI=64M, AHB=64M, APB1=32M, APB2=64M
        2. Port configuration:
            LED1: PB0
            LED2: PA6
            KEY1: PB1
            KEY2: PB2
        3. Log print: DEMO board PB1(TX), baud rate: 115200, 8 data bits, 1 stop bit, no parity bit, no hardware flow control
        4. Bluetooth BLE name: NS_RDTSS
        5. LED1 lights up when it is turned on, LED2 indicates the connection status, and lights up when Bluetooth is connected
        6. BLE Data: USART1 PB6(TX) and PB7(RX), baud rate: 115200, 8 data bits, 1 stop bit, no parity bit, no hardware flow control

    usage method:
        1. Burn to development board after compilation
        2. Power on development board and check the log.
        3. Connect the master device, and send data via USART1 each other.

4. Precautions
    Since the program will enter the sleep mode, the SWD will not be accessible. 
    Press the RESET button to execute the program burning step within one second.