dongle就是USB装置的意思
U盘，SD卡读卡器，3G的USB上网卡，等等之类的都算是dongle
Continuity Activation Tool 的github
https://github.com/dokterdok/Continuity-Activation-Tool/上面说最好是用 BCM20702 芯片的
Bluetooth 4.0 USB dongles
A few important notes about using CAT with USB Bluetooth 4.0 dongles:
Bluetooth 4.0 dongles based on the Cambridge Silicon Radio CSR8510 A10 chip (e.g. Inatek Nano) are not compatible with CAT.
The recommendation is to look for dongles based on the Broadcom BCM20702 chip, which are similar to the ones used by Apple in their Continuity compatible Macs. A few examples: Asus BT400, IOGEAR GBU521, GMYLE, and many others. Compatibility with CSR dongles is not guaranteed.
Instant Hotspot currently doesn't work reliably when using a dongle. This is a known issue, no workarounds have been identified yet.
Atheros Wi-Fi AirPort cards will prevent Continuity from working even when adding a Bluetooth 4.0 dongle. The System Diagnostic feature of CAT tells which Wi-Fi brand is active. There are no workarounds and no patch is expected to change this, an AirPort card upgrade is required.