MRF24XA Datasheet, PDF (173/250 Pages) Texas Instruments – Low-Power, 2.4 GHz ISM-Band IEEE 802.15.4™ RF Transceiver with Extended Proprietary Features

MRF24XA
6.5 Security Processing of
Transmitted Proprietary Frames
Setting TXST triggers automatic security processing
and frame sending as an uninterrupted sequence
(Figure 6-5). Separate security processing, triggered
by TXENC, is only required when both NWK-layer and
MAC-layer security are applied (Figure 6-6). In this
case, TXENC is set to perform NWK-layer security and
TXENCIF shall be awaited, then MAC security is con-
figured and TXST is set to launch the MAC-security
processing and the sending.
The security functions triggered by TXST, BUF1TXPP
(used for debug), BUF2TXPP (used for debug), and
TXENC are shown in Figure 6-5 and Figure 6-6. The
respective interrupts generated on completion and that
the aforementioned triggering bits are cleared by the
device automatically. Figure 6-5 illustrates the
conditions for security material retrieval by the device.
FIGURE 6-5:
TRANSMIT SECURITY PROCESSING WHEN FRMFMT = 1 (PROPRIETARY–
FORMAT)
Before launching the transmit processing (Figure 4-8)
- SW always configures SECKEY, SECSUITE, SECNONCE.
- SW never needs to configure SECHDRINDX, SECPAYINDX, SECENDINDX, except if DTSM = 1.
Enter
MHR parsed already
0
SecEn
1
1
DTSM
0
AHR parsed
No
SecLayer = 00 OR
SecLayer = 10
MAC security
Yes
left to do
SECHDRINDX
1
SECPAYINDX
MACPayIndex
No
SecLayer = 01
SecLayer = 11
is undefined
Yes
NWK security
to do only
SECHDRINDX
SECPAYINDX
NetHdrIndex
NetPayIndex
No security
CTR, CBC-MAC, CCM*
Exit
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Advanced
DS70005023B-page 173