Rainbow Electronics ATmega128RFA1 - Manual (Page 102)

102
8266A-MCU Wireless-12/09
ATmega128RFA1
9.12.3 AES_STATE – AES Plain and Cipher Text Buffer Register
Bit 7 6 5 4 3 2 1 0
NA ($13E) AES_STATE7:0 AES_STATE
Read/Write RW RW RW RW RW RW RW RW
Initial Value 0 0 0 0 0 0 0 0
The AES_STATE register accesses a 16 byte internal data buffer. The buffer is
accessed by reading or writing 16 times to the same address location (AES_STATE). If
the buffer is not completely read or written an error occurs when an AES operation is
started. Note that the AES_STATE register is cleared when entering the radio
transceiver SLEEP state.
• Bit 7:0 – AES_STATE7:0 - AES Plain and Cipher Text Buffer
These bits represent the data buffer for the AES operation.
9.12.4 AES_KEY – AES Encryption and Decryption Key Buffer Register
Bit 7 6 5 4 3 2 1 0
NA ($13F) AES_KEY7:0 AES_KEY
Read/Write RW RW RW RW RW RW RW RW
Initial Value 0 0 0 0 0 0 0 0
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 R R R
Initial Value 0 0 0 0
Bit 3 2 1 0
NA ($141) TRX_STATUS3 TRX_STATUS2 TRX_STATUS1 TRX_STATUS0 TRX_STATUS
Read/Write R R R R
Initial Value 0 0 0 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