Product Specs

Table Of Contents
23 RADIO 2.4 GHz Radio
Page
207
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 on-air. The CRC field is always transmitted and received Most Significant Bit first. The bit-
endian, i.e. which order the bits are sent and received in, of the S0, LENGTH, S1 and PAYLOAD fields can
be configured via the ENDIAN in PCNF1.
The S0INCL field in PCNF0 determines if S0 is present in RAM at all if its length is zero. If present, one byte
is allocated in RAM.
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 bit long the, the least significant
bits of the fields, as seen from the RAM representation, 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.
23.3 Maximum packet length
Independent of the configuration of MAXLEN, the combined length of S0, LENGTH, S1 and PAYLOAD
cannot exceed 258 bytes.
23.4 Address configuration
The on-air radio ADDRESS field is composed of two parts, the base address field and the address prefix
field.
The size of the base address field is configurable via BALEN in PCNF1. The base address is truncated from
LSByte if the BALEN is less than 4. See Table 38: Definition of logical addresses on page 207.
The on-air addresses are defined in the BASEn and PREFIXn registers, and it is only when writing these
registers the user will have to relate to actual on-air addresses. For other radio address registers such as the
TXADDRESS, RXADDRESSES and RXMATCH registers, logical radio addresses ranging from 0 to 7 are
being used. The relationship between the on-air radio addresses and the logical addresses is described in
Table 38: Definition of logical addresses on page 207.
Table 38: Definition of logical addresses
Logical address
Base address
Prefix byte
0
BASE0
PREFIX0.AP0
1
BASE1
PREFIX0.AP1
2
BASE1
PREFIX0.AP2
3
BASE1
PREFIX0.AP3
4
BASE1
PREFIX1.AP4
5
BASE1
PREFIX1.AP5
6
BASE1
PREFIX1.AP6
7
BASE1
PREFIX1.AP7
23.5 Data whitening
The RADIO is able to do packet whitening and de-whitening.
See WHITEEN in PCNF1 register for how to enable whitening. When enabled, whitening and de-whitening
will be handled by the RADIO automatically as packets are sent and received.
The whitening word is generated using polynomial g(D) = D
7
+ D
4
+ 1, which then is XORed with the data
packet that is to be whitened, or de-whitened. See the figure below.