S2-LP datasheet(52/90 Pages) STMICROELECTRONICS

52 / 90 page

Packet handler engine

S2-LP

52/90

DocID029944 Rev 1

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 then 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 LINQ_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.



Length: The device supports both fixed and variable packet length transmission from

0 to 65535 bytes. On the transmitting device, the packet length is always set by using

the two registers PCKTLENx (x= 1, 2) as: PCKTLEN1 × 256 + PCKTLEN0. On the

receiving device, if FIX_VAR_LEN register is set to ‘1’, the packet length is directly

extracted from the field Length of the received packet itself. If the register

FIX_VAR_LEN = 0b the Length field of the received packet is not used, because is

already known from the registers PCKTLENx (x= 1, 2) as for the transmitter.

Furthermore, when variable packet length is used (FIX_VAR_LEN=1b), the width of

the binary field transmitted, must be configured through the LEN_WID register in the

following way:



If the packet length is from 0 to 255 bytes (payload + address field), then

LEN_WID = 0b (1 byte length field transmitted).



If the packet length is from 0 to 65535 bytes (payload + address field), then

LEN_WID = 1b (2 bytes length field transmitted).



Destination address: can be enabled or no by the register ADDRESS_LEN. If

enabled, ADDRESS_LEN=1b, its size is 1 byte. The destination address field is read

from the register RX_SOURCE_ADDR (TX only). The receiver uses this field to

perform automatic filtering on its value programmed in RX_SOURCE_ADDR (RX

only).



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, Address field

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.

S2-LP 数据表(PDF) 52 Page - STMicroelectronics

S2-LP 数据表(HTML) 52 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90

数据表下载