Datasheet

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WIRELESS, SENSING & TIMING DATASHEET
Rev. 2 - July 2014
©2014 Semtech Corporation
Figure 33. Packet Mode Conceptual View
Note The Bit Synchronizer is automatically enabled in Packet mode.
4.2.14.2. Packet Format
Fixed Length Packet Format
Fixed length packet format is selected when bit PacketFormat is set to 0 and PayloadLength is set to any value greater
than 0.
In applications where the packet length is fixed in advance, this mode of operation may be of interest to minimize RF
overhead (no length byte field is required). All nodes, whether Tx only, Rx only or Tx/Rx should be programmed with the
same packet length value.
The length of the payload is limited to 2047 bytes.
The length programmed in PayloadLength relates only to the payload which includes the message and the optional
address byte. In this mode the payload must contain at least one byte i.e. address or message byte.
An illustration of a fixed length packet is shown below. It contains the following fields:
 Preamble (1010...)
 Sync word (Network ID)
 Optional Address byte (Node ID)
 Message data
 Optional 2-bytes CRC checksum
CONTROL
SPI
PACKET
HANDLER
SYNC
RECOG.
DIO1
MISO
MOSI
SCK
NSS
Rx
Tx
Data
FIFO
(+SR)
DIO2
DIO0
DIO3
DIO4
DIO5