NRF52811-QCAA-R datasheet(90/444 Pages) NORDIC

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Peripherals

Property

Address offset

Description

HEADER

Packet Header

LENGTH

Number of bytes in encrypted payload including length of MIC

Important: LENGTH will be 0 for empty packets since the MIC is not added to empty

packets

RFU

Reserved Future Use

PAYLOAD

Encrypted payload

MIC

3 + payload length

ENCRYPT: 4 bytes encrypted MIC

Important: MIC is not added to empty packets

Table 27: Data structure for encrypted packet

6.4.8 EasyDMA and ERROR event

The CCM implements an EasyDMA mechanism for reading and writing to the RAM.

In cases where the CPU and other EasyDMA enabled peripherals are accessing the same RAM block at the

same time, a high level of bus collisions may cause too slow operation for correct on the fly encryption. In

this case the ERROR event will be generated.

The EasyDMA will have finished accessing the RAM when the ENDKSGEN and ENDCRYPT events are

generated.

If the CNFPTR, SCRATCHPTR, INPTR and the OUTPTR are not pointing to the Data RAM region, an EasyDMA

transfer may result in a HardFault or RAM corruption. See Memory on page 16 for more information about

the different memory regions.

6.4.9 Registers

Base address

Peripheral

Instance

Description

Configuration

0x4000F000

CCM

AES CCM mode encryption

Table 28: Instances

Offset

Description

TASKS_KSGEN

0x000

Start generation of key-stream. This operation will stop by itself when completed.

TASKS_CRYPT

0x004

Start encryption/decryption. This operation will stop by itself when completed.

TASKS_STOP

0x008

Stop encryption/decryption

TASKS_RATEOVERRIDE

0x00C

Override DATARATE setting in MODE register with the contents of the RATEOVERRIDE register

for any ongoing encryption/decryption

EVENTS_ENDKSGEN

0x100

Key-stream generation complete

EVENTS_ENDCRYPT

0x104

Encrypt/decrypt complete

EVENTS_ERROR

0x108

CCM error event

Deprecated

SHORTS

0x200

Shortcuts between local events and tasks

INTENSET

0x304

Enable interrupt

INTENCLR

0x308

Disable interrupt

MICSTATUS

0x400

MIC check result

ENABLE

0x500

Enable

MODE

0x504

Operation mode

CNFPTR

0x508

Pointer to data structure holding AES key and NONCE vector

INPTR

0x50C

Input pointer

OUTPTR

0x510

Output pointer

SCRATCHPTR

0x514

Pointer to data area used for temporary storage

4454_140 v1.0

NRF52811-QCAA-R Datasheet(PDF) 90 Page - Nordic Semiconductor

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