NRF52811-QCAA-R7 datasheet(181/444 Pages) NORDIC

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Peripherals

The RADIO includes a device address match unit and an interframe spacing control unit that can be utilized

to simplify address whitelisting and interframe spacing respectively in Bluetooth® low energy and similar

applications.

The RADIO also includes a received signal strength indicator (RSSI) and a bit counter. The bit counter

generates events when a preconfigured number of bits are sent or received by the RADIO.

6.14.1 Packet configuration

A RADIO packet contains the following fields: PREAMBLE, ADDRESS, S0, LENGTH, S1, PAYLOAD, and CRC.

The content of a RADIO packet is illustrated in the figure below. The RADIO sends the fields in the packet

according to the order illustrated in the following figure, starting on the left.

BASE

PREFIX

LENGTH

CRC

PAYLOAD

LSByte

MSByte

LSByte

ADDRESS

PREAMBLE

TERM

TERM1

Figure 58: On-air packet layout

Not shown in the figure is the static payload add-on (the length of which is defined in PCNF1.STATLEN, and

which is 0 bytes in a standard BLE packet). The static payload add-on is sent between PAYLOAD and CRC

fields. The RADIO sends the different fields in the packet in the order they are illustrated above, from left

to right. The preamble will be sent with least significant bit first on air.

PREAMBLE is sent with least significant bit first on air. The size of the PREAMBLE depends on the mode

selected in the MODE register:

• The PREAMBLE is one byte for MODE = Ble_1Mbit as well as all Nordic proprietary operating modes

(MODE = Nrf_1Mbit and MODE = Nrf_2Mbit), and PCNF0.PLEN has to be set accordingly. If the first bit

of the ADDRESS is 0, the preamble will be set to 0xAA. Otherwise the PREAMBLE will be set to 0x55.

• For MODE = Ble_2Mbit, the PREAMBLE must be set to 2 byte through PCNF0.PLEN. If the first bit of the

ADDRESS is 0, the preamble will be set to 0xAAAA. Otherwise the PREAMBLE will be set to 0x5555.

• For MODE = Ble_LR125Kbit and MODE = Ble_LR500Kbit, the PREAMBLE is 10 repetitions of 0x3C.

• For MODE = Ieee802154_250Kbit, the PREAMBLE is 4 bytes and set to all zeros.

Radio packets are stored in memory inside instances of a RADIO packet data structure as illustrated below.

The PREAMBLE, ADDRESS, CI, TERM1, TERM2, and CRC fields are omitted in this data structure. Fields S0,

LENGTH, and S1 are optional.

LENGTH

PAYLOAD

LSByte

Figure 59: In-RAM representation of RADIO packet

The byte ordering on air is always least significant byte first for the ADDRESS and PAYLOAD fields, and

most significant byte first for the CRC field. The ADDRESS fields are always transmitted and received least

significant bit first. The CRC field is always transmitted and received most significant bit first. The bit-

endian, i.e. the order in which the bits are sent and received, of the S0, LENGTH, S1, and PAYLOAD fields

can be configured via PCNF1.ENDIAN.

The sizes of the S0, LENGTH and S1 fields can be individually configured via S0LEN, LFLEN, and S1LEN in

PCNF0 respectively. If any of these fields are configured to be less than 8 bits, the least significant bits of

the fields are used.

If S0, LENGTH, or S1 are specified with zero length, their fields will be omitted in memory. Otherwise each

field will be represented as a separate byte, regardless of the number of bits in their on-air counterpart.

4454_140 v1.0

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NRF52811-QCAA-R7 Datasheet(PDF) 181 Page - Nordic Semiconductor

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