MRF24XA Datasheet, PDF (180/250 Pages) Texas Instruments – Low-Power, 2.4 GHz ISM-Band IEEE 802.15.4™ RF Transceiver with Extended Proprietary Features

MRF24XA
6.8.3 MAC-LAYER SECURITY EXAMPLE 3
• Network configuration: Address size is 1 byte,
Inferred destination addressing
• Source address: 0x01 (is at address 0x1F)
• Destination address: 0x91
• Payload: BA BA
• MAC security level: 0x07
• MAC security indices: Encode only from the sec-
ond payload
• Packet: Data packet
6.8.3.1 Transmission
1. Host MCU constructs the frame and loads the
buffer: 06 || 09 55 91 || 18 || BA BA. Always
encode security indices with DA present in
AUXSECHDR!
2. —
3. —
4. —
5. —
6. Host MCU configures:
- SECSUITE to 0x07
- SECKEY to
0x0F0E0D0C0B0A09080706050403020100,
where LSB (0x00) is at address 0x40
- SECNONCE
0x08070605040302015555555506, where
MSB (0x08) is at address 0x5c
7. Host MCU issues TXST
8. MRF24XA configures:
- SECHDRINDX to 0x01
- SECPAYINDX to 0x06
- SECENDINDX to 0x06
9. MRF24XA performs CCM* authentication with
encryption, where BA BA is encrypted to BA F7,
and the following MIC tag is attached:
35 84 FC 4F 1B 92 36 D2 8F D5 D8 B6 68 79 6A
13
10. MRF24XA appends CRC: 0x23A9
11. MRF24XA transmits the packet to the medium.
Different IF can be received based on the regis-
ter settings (for example, TX with CSMA).
Packet transmitted to the medium:
17 || 09 55 || 18 || BA F7 || 35 84 FC 4F 1B 92 36
D2 8F D5 D8 B6 68 79 6A 13 || A9 23
TX Buffer (0x200) content:
18 || 09 55 91 || 18 || BA F7 || 35 84 FC 4F 1B 92
36 D2 8F D5 D8 B6 68 79 6A 13 || A9 23
6.8.3.2 Reception
1. MRF24XA receives the following packet through
the antenna:
17 || 09 55 || 18 || BA F7 || 35 84 FC 4F 1B 92 36
D2 8F D5 D8 B6 68 79 6A 13 || A9 23
2. MRF24XA configures:
- SECHDRINDX to 0x01
- SECPAYINDX to 0x06 (inferred DA is
considered)
- SECENDINDX to 0x15
3. MRF24XA asserts RXIF (RXSFDIF): Packet
accepted by RX filter
4. —
5. Host MCU configures:
- SECSUITE to 0x07
- SECKEY to
0x0F0E0D0C0B0A09080706050403020100,
where LSB (0x00) is at address 0x40
- SECNONCE to
0x08070605040302015555555506, where
MSB (0x08) is at address 0x5c
6. Host MCU issues RXDEC
7. MRF24XA performs CCM* de-authentication
and decryption, where the MIC tag is compared
against the received one, and BA F7 is
decrypted to BA BA
8. MRF24XA asserts RXDECIF (and IDLEIF)
9. —
10. —
11. —
12. —
13. —
14. —
15. SW read the entire frame from RX Buffer
(0x300):
17 || 09 55 || 18 || BA BA || 35 84 FC 4F 1B 92
36 D2 8F D5 D8 B6 68 79 6A 13 || A9 23 || RSVs
DS70005023B-page 180
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