write

Write Bluetooth LE LL protocol packet data to PCAP or PCAPNG file

Syntax

write(pcapObj,packet,timestamp)

write(pcapObj,packet,timestamp,Name,Value)

Description

write(pcapObj,packet,timestamp) writes Bluetooth^® low energy (LE) link layer (LL) protocol packet data to the packet capture (PCAP) or packet capture next generation (PCAPNG) file specified in the Bluetooth LE PCAP file writer object, pcapObj. Input packet specifies the Bluetooth LE LL protocol packet, and input timestamp specifies the packet arrival time.

write(pcapObj,packet,timestamp,Name,Value) specifies options using one or more name-value pair arguments. For example, 'PacketFormat','bits' sets the format of the Bluetooth LE LL protocol packets to bits.

Examples

Write Bluetooth LE LL Packet to PCAP File

Create a default Bluetooth LE PCAP file writer object.

pcapObj = blePCAPWriter;

Generate a Bluetooth LE LL packet.

cfgLLData = bleLLDataChannelPDUConfig('LLID', ...
    'Data (start fragment/complete)');
payload = '0E00050014010A001F004000170017000000';
llDataPDU = bleLLDataChannelPDU(cfgLLData,payload);
connAccessAddress = de2bi(hex2dec('E213BC42'),32)';
llpacket = [connAccessAddress;llDataPDU];

Write the Bluetooth LE LL packet to the PCAP file.

timestamp = 0;                                        % Packet arrival time in POSIX® microseconds elapsed since 1/1/1970
write(pcapObj,llpacket,timestamp,'PacketFormat','bits');

Use Bluetooth LE PCAP Writer to Write LL Packet to PCAPNG File

Create a Bluetooth LE PCAPNG file writer object, specifying the name and extension of the PCAPNG file.

pcapObj = blePCAPWriter('FileName','sampleBLELL', ...
    'FileExtension','pcapng');

Generate a Bluetooth LE LL packet.

cfgLLData = bleLLDataChannelPDUConfig('LLID', ...
    'Data (start fragment/complete)');
payload = '0E00050014010A001F004000170017000000';
llDataPDU = bleLLDataChannelPDU(cfgLLData,payload);
connAccessAddress = de2bi(hex2dec('E213BC42'),32)';
llpacket = [connAccessAddress; llDataPDU];

Write the Bluetooth LE LL packet to the PCAPNG file.

timestamp = 12800000;                               % Packet arrival time in POSIX® microseconds elapsed since 1/1/1970
write(pcapObj,llpacket,timestamp,'PacketFormat','bits');

Input Arguments

Note

The blePCAPWriter object does not overwrite the existing PCAP or PCAPNG file. Each time when you create this object, specify a unique PCAP or PCAPNG file name.

pcapObj — Bluetooth LE PCAP file writer object

blePCAPWriter object

Bluetooth LE PCAP file writer object, specified as a blePCAPWriter object.

packet — Bluetooth LE LL protocol packet

binary-valued vector | character vector | string scalar | numeric vector | n-by-2 character array

Bluetooth LE LL protocol packet, specified as one of these values.

• Binary-valued vector – This value represents bits.

• Character vector – This value represents octets in hexadecimal format.

• String scalar – This value represents octets in hexadecimal format.

• Numeric vector with each element in the range [0, 255] – This value represents octets in decimal format.

• n-by-2 character array – In this value, each row represents an octet in hexadecimal format.

Data Types: char | string | double

timestamp — Packet arrival time

nonnegative integer

Packet arrival time in POSIX^® microseconds elapsed since 1/1/1970, specified as a nonnegative integer.

Data Types: double

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: 'PacketFormat','bits' sets the format of the Bluetooth LE LL protocol packets to bits.

PhyHeader — Bluetooth LE LL protocol packet metadata

binary-valued vector | character vector | string scalar | numeric vector | n-by-2 character array

Bluetooth LE LL protocol packet metadata, specified as the comma-separated pair consisting of PhyHeader and one of these values.

• Binary-valued vector – This value represents bits.

• Character vector – This value represents octets in hexadecimal format.

• String scalar – This value represents octets in hexadecimal format.

• Numeric vector with each element in the range [0, 255] – This value represents octets in decimal format.

• n-by-2 character array – In this value, each row represents an octet in hexadecimal format.

Data Types: char | string | double

PacketComment — Comment for the Bluetooth LE LL protocol packet

'' (default) | character vector | string scalar

Comment for the Bluetooth LE LL protocol packet, specified as the comma-separated pair consisting of PacketComment and a character vector or a string scalar.

Data Types: char | string

PacketFormat — Format of the Bluetooth LE LL protocol packet

'octets' (default) | 'bits'

Format of the Bluetooth LE LL protocol packet, specified as the comma-separated pair consisting of PacketFormat and 'octets' or 'bits'. If this value is specified as 'octets', packet is specified as one of these values.

• Binary-valued vector – This value represents bits.

• Character vector – This value represents octets in hexadecimal format.

• String scalar – This value represents octets in hexadecimal format.

• Numeric vector with each element in the range [0, 255] – This value represents octets in decimal format.

• n-by-2 character array – In this value, each row represents an octet in hexadecimal format.

Data Types: char | string | double

PhyHeaderFormat — Format of the PHY header

'octets' (default) | 'bits'

Format of the physical layer (PHY) header, specified as the comma-separated pair consisting of PhyHeaderFormat and 'octets' or 'bits'. If you specify this value as 'octets', the PhyHeader argument can be specified as one of these values.

• Binary-valued vector – This value represents bits.

• Character vector – This value represents octets in hexadecimal format.

• String scalar – This value represents octets in hexadecimal format.

• Numeric vector with each element in the range [0, 255] – This value represents octets in decimal format.

• n-by-2 character array – In this value, each row represents an octet in hexadecimal format

Data Types: char | string | double

References

[1] Tuexen, M. “PCAP Next Generation (Pcapng) Capture File Format.” 2020. https://www.ietf.org/.

[2] Group, The Tcpdump. “Tcpdump/Libpcap Public Repository.” Accessed May 20, 2020. https://www.tcpdump.org.

[3] “Development/LibpcapFileFormat - The Wireshark Wiki.” Accessed May 20, 2020. https://www.wireshark.org.

Extended Capabilities

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

Version History

Introduced in R2020b