MRF24J40 Datasheet, PDF (21/66 Pages) Microchip Technology – IEEE 802.15.4™ 2.4 GHz RF Transceiver

MRF24J40
5.0 IEEE 802.15.4™-2003
5.1 Overview
Before discussing the use of the MRF24J40, it may be
helpful to review the structure of a typical data frame.
Users requiring more information should refer to the
IEEE 802.15.4 Standard.
FIGURE 5-1:
PACKET FORMAT
5.2 Packet Format
Normal IEEE 802.15.4 compliant packets are between 5
and 127 bytes long. They are made up of several possi-
ble fields: destination address information, source
address information, a length field, data payload and a
Cyclic Redundancy Check (CRC). Additionally, a 4-byte
preamble field and Start-of-Frame Delimiter (SFD) byte
are appended to the beginning of the packet. Thus, traffic
seen on the air will appear as shown in Figure 5-1.
Used to
calculate
FCS
Number
of
Bytes
4
1
1
2
1
0/4/10
0/2/4/8/
10
Field
Preamble
SFD
Packet Length
Frame Control
Sequence Number
Destination
Address
Information
Source Address
Information
Comments
Filtered
out by
module
Start-of-Frame
delimiter – Filtered
out by module
Short or long address of the destination
device plus the PAN identifier.
Length selected in the frame control.
Short or long address of the source
device plus the PAN identifier.
Length selected in the frame control.
Used to calculate
packet length
0-122
2
Data Payload
FCS
Frame check sequence – CRC
© 2006 Microchip Technology Inc.
Advance Information
DS39776A-page 19