Bluetooth I2CAP

L2CAP:

 

對於下層L2CAP 鏈路層的控制和協議層的調試，對於上層提供連接和無連接的數據服務，允許更好層次的協議和application傳送和接收數據。

 

L2CAP支持的Controller模式：

(1)BR/ENR和AMP（0或者多個）

(2)BR/ENR、BLE和AMP（0或者多個）

(3)BLE

 

 

L2CAP:Channel  Identifier

 

 

 

CID Name Space:

 

 

 

 

 

在兩個設備之間 L2CAP操作：

 

動態申請的例子：

 

operation between layers:

 

 

L2CAP channel 操作的模式：

(1)Basic L2CAP Mode

(2)Flow Control Mode

(3)Retransmission Mode

(4)Enhanced Retransmission Mode

(5)Streamming Mode

(6)LE Credit Based Flow Control Mode

 

 

 

 

 

 

 

 

 

 

 

 

 

Data Packet:

 

 

BASIC L2CAP Mode:

 

connection-oriented:

 

connectionless:

 

 

Flow Control Mode

Retransmission Mode

Enhanced Retransmission Mode:

 

control:2 bytes for 

Flow Control Mode

Retransmission Mode

 

4 bytes for Enhanced Retransmission Mode Streamming Mode

I-frame:發送和接收L2CAP實體

 

S-frame:是爲了識別I-frame和I-frame重傳

 

Control Filed:

 

Standard Control Filed formats:

 

Enhanced Control Field formats:

 

Extended Control Field formats:

 

TxSeq:表明當前I-frame發送的序列

ReqSeq:表明擋牆I-frame接收的序列

 

R: Retransmission Disable Bit 1 enable 0 disable 

 

 

I-frame:在I2CAP實體間傳輸消息

S-frame:用來監控I-frame並且用來要求I-frame的重傳。

TxSeq: 發送序列

RxSeq:接收序列

R:是否需要重新發送

SAR：用來分割或者裝配控制

 

 

 

S:表示S-frame的類型

 

P:設定1 表示請求回覆來自receiver，receiver將立刻回覆frame並且設定F(1)

F:回覆P並且Set 1

 

 

 

 

 

Length:

 

I-payloadInformation Field:

 

Frame Check Sequence(FCS):

 

invalid frame detection（對於Retransmission mode和Flow Control mode）:

(1)包含未知的CID

(2)包含FCS Error

(3)超過MPS

(4)I-frame小於8字節

(5)I-frame （SAR=0x01）小於10字節

(6)I-frame 與SAR不一致

(7)S-frame長度不能等於4

 

invalid frame detection algorihtm：

 

 

Connection-ORIENTED channels in LE creadit BASED flow control mode:

 

Signaling Packet:

 

 

 

 

Command format:

 

Code:

 

Identifier:

 

 

COMMAND REJECT:

 

 

 

 

CONNECTION REQUEST

 

CONNECTION RESPONSE:

 

 

Result:

Status:

 

CONFIGURATION REQUEST:

 

 

CONFIGURATION RESPONSE:

 

DISCONNECTION REQUEST:

DISCONNECTION RESPONSE:

 

ECHO REQUEST:

 

ECHO RESPONSE:

INFORMATION REQUEST:

 

 

InfoType:

 

NFORMATION RESPONSE:

EXTENDED FEATURE MASK:

 

FIXED CHANNELS SUPPORTED:

 

CREATE CHANNEL REQUEST:

CREATE CHANNEL RESPONSE:

 

MOVE CHANNEL REQUEST:

only use in  Enhanced Retransmission and Streaming

 

MOVE CHANNEL RESPONSE:

MOVE CHANNEL CONFIRMATION:

 

MOVE CHANNEL CONFIRMATION RESPONSE:

 

CONNECTION PARAMETER UPDATE REQUEST:

BLE Slave ------> BLE Master (only)

CONNECTION PARAMETER UPDATE RESPONSE:

BLE Master ----> BLE Slave

LE CREDIT BASED CONNECTION REQUEST:

 

LE_PSM:

LE CREDIT BASED CONNECTION RESPONSE:

LE FLOW CONTROL CREDIT: