MRF24J40-I MICROCHIP [Microchip Technology], MRF24J40-I Datasheet - Page 21

• Manufacturer Part Number: MRF24J40-I
• Manufacturer: MICROCHIP [Microchip Technology]

5.0
5.1
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:
© 2006 Microchip Technology Inc.
IEEE 802.15.4™-2003
Overview
Used to
calculate
FCS
Used to calculate
packet length
PACKET FORMAT
Number
0/2/4/8/
0/4/10
0-122
Bytes
10
of
4
1
1
2
1
2
Advance Information
Sequence Number
Source Address
Packet Length
Frame Control
Data Payload
Destination
Information
Information
Preamble
Address
Field
SFD
FCS
5.2
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.
Comments
Packet Format
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.
Frame check sequence – CRC
MRF24J40
DS39776A-page 19