RFM66W Datasheet, PDF (55/87 Pages) List of Unclassifed Manufacturers – 868 & 915MHz Ultra Low Power High Link Budget Integrated UHF Transceiver

WIRELESS & SENSING
RFM66W
DATASHEET
CONTROL
DIO0
DIO1
DIO2
DIO3
DIO4
DIO5
Data Rx
SYNC
RECOG.
Tx
PACKET
HANDLER
FIFO
(+SR)
SPI
NSS
SCK
MOSI
MISO
Figure 31. Packet Mode Conceptual View
Note The Bit Synchronizer is automatically enabled in Packet mode.
5.5.2. Packet Format
5.5.2.1. 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
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