Packet configuration

nRF54L15 | nRF54L10 | nRF54L05 Datasheet

A RADIO packet contains the fields PREAMBLE, ADDRESS, S0, LENGTH, S1, PAYLOAD, and CRC. For Long Range (125 kbps and 500 kbps) Bluetooth Low Energy modes, fields CI, TERM1, and TERM2 are also included.

The content of a RADIO packet is illustrated in the following figures. RADIO sends the fields in the packet according to the sequence shown in the figures, starting on the left.

Figure 2. On-air packet layout
On-air packet layout
Figure 3. On-air packet layout for Long Range (125 kbps and 500 kbps) Bluetooth Low Energy modes
On-air packet layout for Long Range (125 kbps and 500 kbps) Bluetooth Low Energy modes
Not shown in the figures 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. RADIO sends the different fields in the packet in the order they are illustrated above, from left to right.

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

Table 1. Preamble size according to mode
Preamble
MODE PCNF0.PLEN When first bit of ADDRESS is 0 When first bit of ADDRESS is 1
Ble_1Mbit 1 0xAA 0x55
Nrf_1Mbit 1 0xAA 0x55
Nrf_2Mbit 1 0xAA 0x55
Ble_2Mbit 2 0xAAAA 0x5555
Nrf_4Mbit_0BT4 2 0xAAAA 0x5555
Nrf_4Mbit_0BT6 2 0xAAAA 0x5555
Ble_LR125Kbit Any 10 repetitions of 0x3C
Ble_LR500Kbit Any 10 repetitions of 0x3C
Ieee802154_250Kbit Any 4 repetitions of 0x00

Radio packets are stored in memory inside instances of a RADIO packet data structure as shown in the following figure. The PREAMBLE, ADDRESS, CI, TERM1, TERM2, and CRC fields are omitted in this data structure. Fields S0, LENGTH, and S1 are optional.

Figure 4. Representation of a RADIO packet in RAM
Page-1 Class.397 Sheet.7 Sheet.8 Sheet.9 Sheet.10 Sheet.11 S0 S0 Class.403 Sheet.13 Sheet.14 Sheet.15 Sheet.16 Sheet.17 LENGTH LENGTH Class.409 Sheet.19 Sheet.20 Sheet.21 Sheet.22 Sheet.23 S1 S1 Class.433 Sheet.25 Sheet.26 Sheet.27 Sheet.28 Sheet.29 PAYLOAD PAYLOAD Dynamic connector.448 Dynamic connector.449 Dynamic connector.455 Dynamic connector.457 Dynamic connector.458 Sheet.36 0 0 Sheet.37 n n Sheet.38 LSByte LSByte Dynamic connector.39 Dynamic connector.40

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 endianness, meaning 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.

Independent of the configuration of PCNF1.MAXLEN, the combined length of S0, LENGTH, S1, and PAYLOAD cannot exceed 258 bytes.