add data logging function.

[liubenyuan]

Can I log data in HexNanoController_iOS using bluetooth as a RS232 interface ? so that the parameter of flexbot can be online recorded.

Liu

[HexAirbot]

The BLE 4.0 module of FlexBot works as peripheral device， any center BLE devicies can use BLE protocol to find and connect to the module.

In V1.5 FlexBot Board, with the new BT module, full duplex communication is supported, so the info (such as attitude, battery leve) of Flexbot can be sended back to the App.

More about the new BT module is here: https://github.com/HexAirbot/FlexBLE