
112
42073A-MCU Wireless-02/13
ATmega2564/1284/644RFR2
The AES key register accesses a 128 Bit internal buffer that holds the Encryption or
Decryption Key. The AES_KEY buffer is a 16 Byte buffer. The buffer is accessed by
reading or writing 16 fold to the same address location (AES_KEY). A read access to
registers AES_KEY returns the last round key of the preceding security operation. This
is the key that is required for the corresponding ECB decryption operation after an ECB
encryption operation. However, the initial AES key written to the security module in
advance of an AES run is not modified during an AES operation. This initial key is used
for the next AES run even if it cannot be read from AES_KEY register. Note that the
AES_KEY register is cleared when entering the radio transceiver SLEEP state.
Bit 7:0 – AES_KEY7:0 - AES Encryption/Decryption Key Buffer
These bits represent the data buffer for the AES Encryption/Decryption key.
9.12.5 TRX_STATUS – Transceiver Status Register
Bit
7
6
5
4
NA ($141)
CCA_DONE
CCA_STATUS
TST_STATUS
TRX_STATUS4
TRX_STATUS
Read/Write
R
Initial Value
0
Bit
3
2
1
0
NA ($141)
TRX_STATUS3
TRX_STATUS2
TRX_STATUS1
TRX_STATUS0
TRX_STATUS
Read/Write
R
Initial Value
0
This read-only register signals the present state of the radio transceiver as well as the
status of the CCA operation. A state change is initiated by writing a state transition
command to the TRX_CMD bits of register TRX_STATE. The register is not accessible
in SLEEP state.
Bit 7 – CCA_DONE - CCA Algorithm Status
This bit indicates if a CCA request is completed. This is also indicated by a
TRX24_CCA_ED_DONE interrupt. Note that register bit CCA_DONE is cleared in
response to a CCA_REQUEST.
Table 9-34 CCA_DONE Register Bits
Register Bits
Value
Description
CCA_DONE
0
CCA calculation not finished
1
CCA calculation finished
Bit 6 – CCA_STATUS - CCA Status Result
The result of the CCA measurement is available in register bit CCA_STATUS after a
CCA request is completed. Note that register bit CCA_STATUS is cleared in response
to a CCA_REQUEST.
Table 9-35 CCA_STATUS Register Bits
Register Bits
Value
Description
CCA_STATUS
0
Channel indicated as busy.
1
Channel indicated as idle.
Bit 5 – TST_STATUS - Test mode status
This bit is reserved for internal use. It indicates the status of the test mode.