May be you can check the next two posts, they’re about related subjects, so maybe you can find them of help.
If you have any more doubts, don't hesitate to ask.
Thanks for the information. I did get the BLE connected in the Linux Command Line environment. However, what I need to do is to control the BLE in the Arduino application level. Just like adding the WiFi library in the Arduino IDE and program it to control WiFi scan, connect etc. I could find libraries like NordicSemiconductor/ble-sdk-arduino · GitHub and RedBearLab/nRF8001 · GitHub, but those libraries are for Nordic nRF8001 BLE chipset. Any other suggestions? Thank you very much.