MRF24XA_15 Datasheet, PDF (133/258 Pages) Microchip Technology – Low-Power, 2.4 GHz ISM-Band IEEE 802.15.4™ RF

MRF24XA
5.0 IEEE 802.15.4™ COMPLIANT
FRAME FORMAT AND FRAME
PROCESSING
Figure 5-1 shows the general MAC header structure.
The specific format of the Acknowledge frame is pro-
vided in Figure 5-2. The frame buffer is written in the
following sequence: (1) LENGTH field byte, (2) Byte 0
of the FrameCtrl field, (3) Byte 1 of the FrameCtrl field,
and (4) SEQUENCE.
FIGURE 5-1:
IEEE.802.15.4™ MAC HEADER STRUCTURE
MHR: MAC Header (IEEE 802.15.4™)
FrameCtrl
(2 octets)
Sequence
(1 octet)
DestPID
DestAddr
(0/2 octets) (0/2/8 octets)
Destination (0/4/10 octets)
SrcPID
(0/2 octets)
SrcAddr
(0/2/8 octets)
Source(0/2/4/8/10 octets)
AuxSecHdr
(0-14 octets)
FrameCtrl (IEEE 802.15.4)
7
6
Byte 0
5
4
3
2:0
Rsvd. PIDCmp AckReq FramePend SecEn Type
(1 bit) (1 bit) (1 bit)
(1 bit)
(1 bit) (3 bits)
7:6
SAMode
(2 bits)
Byte 1
5:4
3:2
FrameVer DAMode
(2 bits)
(2 bits)
1:0
Rsvd.
(2 bits)
• Type<2:0>: Indicates the frame type. For more
information, see Section 5.1 “Frame Types in
IEEE 802.15.4-Compliant Framing Mode”.
• SecEn: Security Enable bit. For more information,
see Section 5.3 “Security Material” and
Section 5.4 “Security Material Retrieval with
IEEE 802.15.4 Compliant Frames”.
• FramePend: This bit of the ACK frame must be
set when ACKTXFP = 1 and the frame being
ACK’d is an 802.15.4 Data Request Command
Frame (FrameCtrl.Type = 011 AND CMDType =
0x04), and cleared otherwise. CSMA-CA is not
performed before sending out ACK packets.
• AckReq: ACK Request. For more information, see
Section 4.12 “Clear Channel Assessment
(CCA)”.
• PIDCmp: PAN Identifier Compare. For more
information, see Section 5.2 “Addressing in
IEEE 802.15.4 Compliant Framing Mode”.
• DAMode: Destination Address Mode. For more
information, see Section 5.2 “Addressing in
IEEE 802.15.4 Compliant Framing Mode”.
• SAMode: Source Address Mode. For more
information, see Section 5.2 “Addressing in
IEEE 802.15.4 Compliant Framing Mode”.
 2015 Microchip Technology Inc.
Preliminary
DS70005023C-page 133