MRF24XA_15 Datasheet, PDF (157/258 Pages) Microchip Technology – Low-Power, 2.4 GHz ISM-Band IEEE 802.15.4™ RF

MRF24XA
5.5 Transmit Security Processing of
IEEE 802.15.4 Compliant Frames
Setting TXST triggers automatic MAC layer security
processing and frame sending as an uninterrupted
sequence, see Figure 5-14. (network layer) which is
triggered by TXENC is applied, where TXENCIF must
be awaited before other operation.
BUF1TXPP, BUF2TXPP, TXENC, and TXST can trig-
ger security functions as shown in Figure 5-12 and
Figure 5-14, where BUF1TXPP and BUF2TXPP are
both used for debug. The respective interrupts are gen-
erated on completion and the device automatically
clears the aforementioned triggering bits. In Figure 5-
12, the device shows the conditions for security mate-
rial retrieval and the operation of the DTSM bit.
FIGURE 5-14:
TRANSMIT SECURITY PROCESSING WHEN FRMFMT = 0 (IEEE 802.15.4™
FORMAT)
Before launching the transmit processing (Figure 4-9):
• SW always configures SECKEY
• SW may configure SECSUITE, SECNONCE, SECHDRINDX, SECPAYINDX, SECENDINDX
Enter
MHR Parsed
SecEn
MAC Security
1
DTSM
1
0
0
SAMode
Parse AHR
Configure SECSUITE,
SECNONCE, SECHDRINDX,
SECPAYINDX, SECENDINDX.
no security
CTR, CBC-MAC, CCM*
LENTGH is incremented when a MIC tag is
attached. TXSZIF is set when LENGTH>0x7F.
Exit
 2015 Microchip Technology Inc.
Preliminary
DS70005023C-page 157