MRF24XA_15 Datasheet, PDF (163/258 Pages) Microchip Technology – Low-Power, 2.4 GHz ISM-Band IEEE 802.15.4™ RF

MRF24XA
TABLE 5-14: SECURED FRAME RECEPTION (IEEE 802.15.4™ MAC FORMAT)
#
Processing Step
Steps per each security case
A
B
C
D
E
-2 Device parses the SecEn bit in the
FrameCtrl.
SecEn = 1
SecEn = 1
SecEn = 0
SecEn = 1
SecEn = 1
-1 For MAC security processing, the
device configures (correctly or incor-
rectly) the
following:
SECSUITE
SEC*INDX
NONCE
incorrect
No MAC layer
Configuration
security
SECSUITE
SEC*INDX
NONCE
incorrect
Configuration
0 Valid frame received on air and
accepted by RXFILTER.
RXIF = 1, RXBUFFUL = 1, (RXSFDIF = 1)
1 Host MCU has the opportunity to check FrameVer =
the SecEn, FrameVer and SAMode bits 0x (either)
in the MAC header.
FrameVer =
0x (either)
FrameVer =
0x (either)
FrameVer =
0x (either)
FrameVer =
0x (either)
2 For MAC security processing, the Host
SECKEY
MCU must load the following:
(+NONCE if
SAMode is not
11)
SECKEY
SECSUITE
SEC*INDX
NONCE
SECKEY
(+NONCE if
SAMode is not
11)
SECKEY
SECSUITE
SEC*INDX
NONCE
3 Host MCU starts MAC security pro-
cessing by setting RXDEC.
4 Device performs MAC layer security
processing as illustrated in Figure 5-4
through Figure 5-9.
RXDEC ← 1
MAC layer
RXDEC ← 1
MAC layer
No
MAC layer
Security
RXDEC ← 1
MAC layer
RXDEC ← 1
MAC layer
5 If Authentication fails then RXTAGIF is
generated. Otherwise, the security
operation is successful and RXDECIF
is generated.
RXDECIF (or
RXTAGIF)
RXDECIF (or
RXTAGIF)
RXDECIF (or
RXTAGIF)
RXDECIF (or
RXTAGIF)
6 SW examines RXTAGIF, if set, SW
RXTAGIF ← 1 RXTAGIF ← 1
aborts further processing and frees the
buffer by clearing RXBUFFUL..
RXTAGIF ← 1 RXTAGIF ← 1
7 For NWK security processing, the Host
MCU must load the following:
No
NWK layer security
SECKEY
SECSUITE
SEC*INDX
NONCE
SECKEY SEC-
SUITE
SEC*INDX
NONCE
SECKEY SEC-
SUITE
SEC*INDX
NONCE
8 Host MCU starts NWK security
processing by setting RXDEC.
RXDEC ← 1 RXDEC ← 1 RXDEC ← 1
9 Device performs NWK layer security
processing. (No figure)
NWK layer
security
NWK layer
security
NWK layer
security
10 If Authentication fails , RXTAGIF is gen-
erated. Otherwise, the security opera-
tion is successful and RXDECIF is
generated. The device clears RXDEC.
RXDECIF (or
RXTAGIF)
RXDEC ← 0
RXDECIF (or
RXTAGIF)
RXDEC ← 0
RXDECIF (or
RXTAGIF)
RXDEC ← 0
11 SW examines RXTAGIF, if set, SW
aborts further processing and frees the
buffer by clearing RXBUFFUL.
For the length
12 SW reads the entire frame from the
—
buffer.
13 SW clears the RXBUFFUL to free the
—
buffer.
 2015 Microchip Technology Inc.
Preliminary
DS70005023C-page 163