MRF24XA_15 Datasheet, PDF (179/258 Pages) Microchip Technology – Low-Power, 2.4 GHz ISM-Band IEEE 802.15.4™ RF

MRF24XA
TABLE 6-7: SECURED FRAME RECEPTION (PROPRIETARY MAC FORMAT)
#
Processing Step
Steps per each Security Case
MAC only
NWK only
MAC + NWK layer
-2 Device parses the SecEn bit in the FrameCtrl.
SecEn = 1
SecEn = 1
SecEn = 1
-1 For MAC security processing, the device config- SEC*INDX from SEC*INDX from
ures the SECHDRINDX, SECPAYINDX based on MacHdrIndex, NetHdrIndex, Net-
the Auxiliary Security Header, as well as the
MacPayIndex and PayIndex and the
SECENDINDX based on the LENGTH field.
the LENGTH
LENGTH
SEC*INDX from
MacHdrIndex,
MacPayIndex and
the LENGTH
0 Valid frame received and accepted by RXFILTER.
1 Host MCU reads the frame header to check
SecEn, SecLayer, source address, and so on.
RXIF = 1, RXBUFFUL = 1, (RXSFDIF = 1)
Read frame header from buffer.
2 For MAC security processing, the Host MCU must
load the following:
SECKEY
NONCE
SECSUITE
No
MAC layer security
SECKEY
NONCE
SECSUITE
3 Host MCU starts MAC security processing by set- Host: RXDEC ←1
ting RXDEC.
Host: RXDEC ←1
4 Device performs MAC layer security.
MAC layer security
MAC layer security
5 If SecLayer = 10 then SEC*INDX are filled in
—
preparation for network layer security processing
following in the sequel.
SEC*INDX from
NetHdrIndex, Net-
PayIndex and the
MAC layer MIC-posi-
tion (if present)
6 If Authentication fails then RXTAGIF is generated
otherwise the security operation is successful and
RXDECIF is generated. Device clears RXDEC.
7 SW examines RXTAGIF. If set, SW aborts further
processing and frees the buffer by clearing
RXBUFFUL.
RXDECIF (or
RXTAGIF)
RXDEC ← 0
RXTAGIF ←1
RXDECIF
(or RXTAGIF)
RXDEC ← 0
RXTAGIF ←1
8 For NWK security processing, the Host MCU must
No
load the following:
NWK layer security
SECKEY
SECSUITE
NONCE
SECKEY
SECSUITE
NONCE
9 Host MCU starts NWK security processing by set-
ting RXDEC.
Host: RXDEC ←1 Host: RXDEC ←1
10 Device performs NWK layer security processing.
(No figure).
NWK layer
security
NWK layer
security
11 If Authentication fails then RXTAGIF is generated.
Otherwise, the security operation is successful
and RXDECIF is generated. Device clears
RXDEC.
RXDECIF (or
RXTAGIF)
RXDEC ← 0
RXDECIF
(or RXTAGIF)
RXDEC ← 0
12 SW examines RXTAGIF. If set, SW aborts further
processing and frees the buffer by clearing
RXBUFFUL.
RXTAGIF ←1
RXTAGIF ←1
13 SW reads the payload from the buffer.
—
—
14 SW clears the RXBUFFUL to free the buffer.
RXBUFFUL ← 0
 2015 Microchip Technology Inc.
Preliminary
DS70005023B-page 179