Bluetooth

Bluetooth uses the same 2.4Ghz ISM band as WIFI, it uses 80 channels of 1Mhz and all the channels through frequency hopping. The idea of bluetooth was to be a wireless version of usb, but many releases later the reality is more complicated. Bluetooth 2 added EDR to increase the datarate. BL5 added BLE Bluetooth Low Energy, coexists with Bluetooth, but is incompatible. It uses 40 channels of 2Mhz and originates from Nokia Wibree. Bluetooth has GATT device Generic Attribute Profiles, similar to the USB devices. Bluetooth support a PAN personal network and in BL5 also Bluetooth Mesh exists, which uses 802.15.4 as physical access. Both android and linux use bluez as default bluetooth stack

systemctl status hciuart.service
rfkill list all
modprobe btusb

hcitool dev
hcitool scan
hciconfig features
bluetoothctl version

bluetoothctl
del 38:78:62:A6:29:BD
connect 38:78:62:A6:29:BD
info 38:78:62:A6:29:BD 
list
devices
power on
scan on
pair
trust

lspci -v