LED: The flicker frequency of slave device is 102ms.
If master device already has the memory of slave device, the flicker frequency during the pairing is 110ms/s.
If not, or master has emptied the memory, then the flicker frequency is 750m/s.
After pairing, no matter it’s a master or slave device, the LED PIN is at high level.
Notice: The LED PIN connects to LED+ PIN.