Bluetooth Stack
Last updated
Last updated
L2CAP – Logical Link Control and Adaptation Protocol.
LMP – Link Manager Protocol.
HID – Human Interface Device.
RFCOMM – serial cable emulation (ETSI).
Bluetooth includes:
A HW description.
An environment for applications.
Radio layer.
Defines requirements for a Bluetooth radio transceiver.
Handles conformity to 2.4GHz band.
Establishes specifications for using Spread-Spectrum Frequency Hopping.
Classifies device into one of three power classes:
long range; (Class 1 - 100mW, 100m)
normal/standard range; (Class 2 - 2.5mW, 10m)
short range; (Class 3 - 1 mW, 1m)
2.4GHz issues.
Channel BW limited to 1MHz.
Spread spectrum must be used.
Multiple independent networks can interfere.
Microwave ovens also use these frequencies.
ICs at 2.4 GHz need huge current levels.
Bluetooth remedies.
1 Mb/s baud taxes exploit BW at maximum.
Voice coding (CVSDM) allow high speed operation.
Fast “frequency hoping” and small packets to avoid interference.
Interface with the channel minimizes power consumption.
Interface specifications are relaxed enough to allow its integration in low power chipsets.
Radio: FH SS.
79/23 channels of 1 Mb/s.
Hoping: per slot.
Packets have 1, 3, or 5 slots of 625 μs.
Hoping (nominal) 1600 times per second.
Frame includes two packets.
Transmission followed by reception.
Radio designed to low cost and universal usage.
(noise, synchronous action technology 2.4GHz, etc...).
