S2-LP datasheet(54/90 Pages) STMICROELECTRONICS

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Packet handler engine

S2-LP

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

Sequence number: it is a 2 bits field and contains the sequence number of the

transmitted packet. It is incremented automatically every time a new packet is

transmitted. It can be manually updated with the SEQUENCE_UPDATE command.



NO_ACK: it is 1 bit field that notify to the receiver if the packet has to be

acknowledged or not. This bit must be used only in STack packet format.



Payload: the main data from transmitter with a max length up to 65535 supported by

the embedded automatic packet handler.



CRC: can optionally be calculated on the transmitted data (Length field, Destination

Address field, Source Address field, Sequence Number, No Ack and Payload) and

appended at the end of the payload (see Section 7.9: "CRC").



Postamble

: The packet postamble allows inserting a certain number of ‘01’ bit pairs at

the end of the data packet. The number of postamble bit pairs can be set through the

MBUS_PSTMBL register.

7.3

802.15.4g packet

Table 51: 802.15.4g packet

Preamble

Sync

PHR

MHR + MAC Payload

CRC

0:2046 bits

0:32 bits

2 bytes

2:2047 bytes

0:4 bytes



Preamble:

each preamble is a pair of ‘01’ or ‘10’ from 0 pair to 2046 pairs,

programmed by the register PREAMBLE_LENGTH. The binary sequences transmitted

in the various modulation modes are summarized in Table 49: "Preamble field

selection" (leftmost bit is transmitted first).



Sync: the pattern that identify the start of the frame can be configured in value with a

programmable length from 0 to 32 bits, in steps of 1-bit length. The setting is done by

the register SYNC_LENGTH. The S2LP supports dual synchronization with a either a

primary or a secondary synchronization word. The binary content of the primary SYNC

word is programmable through registers SYNCx (x= 1, 2, 3, 4). The binary content of

the secondary SYNC word is programmable through registers SEC_SYNCx (x= 1, 2,

3, 4), note that such registers are in alternate use with address filtering registers. On

the transmitter side either the primary or the secondary word is transmitted according

to the value of the SECONDARY_SYNC_SEL register, in particular if

SECONDARY_SYNC_SEL = 0, the primary synchronization word is transmitted; if

SECONDARY_SYNC_SEL = 1 then the secondary synchronization word is

transmitted. On the receiver side, the primary synchronization word is always enabled.

The search for the secondary synchronization word can be enabled setting

SECONDARY_SYNC_SEL = 1b. In this case, both the binary patterns are searched

for and both of them can trigger the start of payload demodulation. The SQI[5:0] value

reported in the LINK_QUALIF register is the maximum between the SQI of the primary

and secondary words. The bit SQI[6] indicates which synchronization word has been

detected: in particular, if the secondary synchronization word has been detected then

the SQI[6] = 1b otherwise if the primary synchronization word has been detected then

SQI[6] = 0b. The binary pattern programmed in SYNCx (or SEC_SYNCx) is

transmitted on air starting with the most significant bit of x = 1, to the least significant

bit of x = 4 according to the programmed synchronization word length. For the

802.15.4g packet format, the secondary synchronization word is automatically

selected on the TX side and enabled on the RX side when FEC is enabled (FEC_EN

= 1) and the setting of SECONDARY_SYNC_SEL is ignored.



PHR: The PHR (Physical Header) field is specific for the 802.15.4g packet format and

is automatically built by the packet handler block based on current register

configuration.

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