bleL2CAPFrameDecode

Decode Bluetooth LE L2CAP frame

Syntax

[status,cfgL2CAP,sdu] = bleL2CAPFrameDecode(l2capFrame)

Description

[status,cfgL2CAP,sdu] = bleL2CAPFrameDecode(l2capFrame) decodes the specified Bluetooth^® low energy (LE) logical link control and adaptation protocol (L2CAP) frame, l2capFrame. The function returns the decoding status, status, the corresponding Bluetooth LE L2CAP configuration object, cfgL2CAP, and the upper-layer payload service data unit (SDU), sdu.

Examples

Decode Bluetooth LE L2CAP Data Frame with SDU

Create a default Bluetooth LE L2CAP configuration object. Set the value of channel identifier to '0004'.

cfgL2CAP = bleL2CAPFrameConfig

cfgL2CAP = 
  bleL2CAPFrameConfig with properties:

          ChannelIdentifier: '0005'
                CommandType: 'Credit based connection request'
           SignalIdentifier: '01'
    SourceChannelIdentifier: '0040'
                      LEPSM: '001F'
        MaxTransmissionUnit: 23
          MaxPDUPayloadSize: 23
                    Credits: 1

cfgL2CAP.ChannelIdentifier = '0004';

Generate a Bluetooth LE L2CAP data frame from 'cfgL2CAP', specifying the upper-layer payload SDU from attribute protocol (ATT) layer as '0A0100'.

L2CAPFrame = bleL2CAPFrame(cfgL2CAP,"0A0100");

Decode the generated Bluetooth LE L2CAP data frame. The returned status indicates decoding was successful.

[status,cfgL2CAP,SDU] = bleL2CAPFrameDecode(L2CAPFrame)

status = 
  blePacketDecodeStatus enumeration

    Success

cfgL2CAP = 
  bleL2CAPFrameConfig with properties:

    ChannelIdentifier: '0004'

SDU = 3x2 char array
    '0A'
    '01'
    '00'

Decode Corrupted Bluetooth LE L2CAP Frame

Specify a Bluetooth LE L2CAP frame containing corrupted data values.

l2capFrame = ['090005000107040060005000'];

Decode the specified Bluetooth LE L2CAP frame. The returned status indicates that the decoding failed due to the corrupted input L2CAP frame. If the decoding fails, the output displays the reason of failure and the object displays no properties.

[status,cfgL2CAP,sdu] = bleL2CAPFrameDecode(l2capFrame)

status = 
  blePacketDecodeStatus enumeration

    MismatchL2CAPHeaderLength

cfgL2CAP = 
  bleL2CAPFrameConfig with properties:

sdu =

  1x0 empty char array

Input Arguments

l2capFrame — Bluetooth LE L2CAP frame

character vector of octets in hexadecimal format | string scalar of octets in hexadecimal format | numeric vector of elements in range [0, 255] | n-by-2 character array

Bluetooth LE L2CAP frame, specified as one of these values:

• Character vector — This vector represents octets in hexadecimal format.

• String scalar — This scalar represents octets in hexadecimal format.

• Numeric vector of elements in the range [0, 255] — This vector represents octets in decimal format.

• n-by-2 character array — Each row represents an octet in hexadecimal format.

Data Types: char | double | string

Output Arguments

status — Packet decoding status

nonpositive integer

Packet decoding status, returned as a nonpositive integer of type blePacketDecodeStatus. This value represents the result of decoding a Bluetooth LE L2CAP frame. Each value of status corresponds to a member of the blePacketDecodeStatus enumeration class, which indicates the packet decoding status according to this table.

Value of status	Member of Enumeration Class	Decoding Status
0	Success	Packet decoding succeeded
–301	InvalidL2CAPConnectionIntervalRange	Invalid connection intervals
–302	InvalidL2CAPPeripheralLatency	Invalid Peripheral latency
–303	InvalidLECredits	Invalid low energy (LE) credits
–304	L2CAPSegmentationUnsupported	Segmentation is not supported
–305	MismatchL2CAPHeaderLength	Length mismatches with actual length
–306	IncompleteL2CAPDataFrame	L2CAP data frame is not sufficient to decode
–307	InvalidL2CAPChannelIdentifier	Invalid L2CAP channel identifier
–308	InvalidL2CAPCommand	Invalid L2CAP command code
–309	InvalidL2CAPCommandRejectReason	Invalid command reject reason code
–310	InvalidL2CAPParameterUpdateResult	Invalid parameters update result
-311	InvalidL2CAPConnectionResult	Invalid connection result code
-312	IllegalL2CAPSignalIdentifier	Illegal signal identifier in L2CAP
-313	InvalidL2CAPConnectionIntervalMinimum	Invalid interval minimum
-314	InvalidL2CAPConnectionIntervalMaximum	Invalid interval maximum
-315	InvalidL2CAPConnectionTimeout	Invalid connection timeout
-316	InvalidLEPSM	Invalid LE protocol/service multiplexer
-317	InvalidL2CAPChannelMTU	Invalid maximum transmission unit
-318	InvalidL2CAPChannelMPS	Invalid maximum PDU payload size
-319	InvalidL2CAPSDULength	Invalid SDU length
-320	MismatchL2CAPSignalFrameLength	Length mismatches with actual length
-321	IncompleteL2CAPSignalFrame	L2CAP signal frame is not valid or not sufficient

An enumeration value other than 0 implies failed Bluetooth LE ATT PDU decoding. If the decoding fails, the cfgATT object displays no output.

cfgL2CAP — Bluetooth LE L2CAP frame configuration object

bleL2CAPFrameConfig object

Bluetooth LE L2CAP frame configuration object, returned as a bleL2CAPFrameConfig object.

sdu — Upper-layer payload

character array of octets in hexadecimal format

Upper-layer payload, returned as a character array. Each row of the array represents an octet in hexadecimal format.

Data Types: char | string

References

[1] Bluetooth Technology Website. “Bluetooth Technology Website | The Official Website of Bluetooth Technology.” Accessed November 22, 2021. https://www.bluetooth.com/.

[2] Bluetooth Special Interest Group (SIG). "Bluetooth Core Specification." Version 5.3. https://www.bluetooth.com/.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2019b