STS1TX datasheet(34/70 Pages) STMICROELECTRONICS

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Transmission and reception

STS1TX

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DocID025109 Rev 1

Three registers are available to use the AES engine of STS1TX:

•

AES_KEY_IN [15:0]: R/W type register (128-bit), used to provide the key to use

•

AES_DATA_IN [15:0]: R/W type register (128-bit), used to provide the input to the AES

engine

•

AES_DATA_OUT [15:0]: R type register (128-bit), used to retrieve the output of the

AES operation.

The core processes 128-bit data blocks using 128-bit keys.

The AES can be accessed in any of the STS1TX operation modes.

To turn on the AES engine, the AES_ON bit in the ANA_FUNC_CONF[0] register must be

set.

Once the AES engine is on, it processes the operations according to the commands sent.

The STS1TX engine provides 4 different operations:

Encryption using a given encryption key (AES Enc command). In this operation, the

MCU puts the encryption key into the AES_KEY_IN[15:0] register and the data to

encrypt into the AES_DATA_IN[15:0]. The MCU sends the AES Enc command and

when the AES_EOP (end of operation) is issued, the MCU can retrieve the data

encrypted from AES_DATA_OUT[15:0]

Decryption key derivation starting from an encryption key (AES Key command). In this

operation, the MCU puts the encryption key into AES_DATA_IN[15:0]. The MCU sends

the AES Key command and when the AES_EOP (end of operation) is issued, the MCU

can retrieve the decryption key from AES_DATA_OUT[15:0]

Data decryption using a decryption key (AES Dec command). In this operation, the

MCU puts the decryption key into the AES_KEY_IN[15:0] register and the data to

decrypt into AES_DATA_IN[15:0]. The MCU sends the AES Dec command and when

the AES_EOP (end of operation) is issued, the MCU can retrieve the data decrypted

from AES_DATA_OUT[15:0].

Data decryption using a decryption key (AES KeyDec command). In this operation, the

MCU puts the encryption key into the AES_KEY_IN[15:0] register and the data to

decrypt into AES_DATA_IN[15:0]. The MCU sends the AES KeyDec command and

when the AES_EOP (end of operation) is issued, the MCU can retrieve the data

decrypted from AES_DATA_OUT[15:0].

Transmission and reception

9.1

PA configuration

The PA output power level can be configured by programming the PA_POWER[8:0] register

bank. The user can store up to eight output levels to provide flexible PA power ramp-up and

ramp-down at the start and end of a frequency modulation transmission as well as ASK

modulation shaping.

The power levels of the ramp are controlled by 7-bit words (PA_LEVEL_x, x=0

− 7),

according to the following table:

STS1TX Datenblatt(PDF) 34 Page - STMicroelectronics

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