RF98 datasheet(68/121 Pages) HOPE

68 / 121 page

Page 68

RF96/97/98

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WIRELESS & SENSING

PRELIMINARY

DATASHEET

Optional DC free data coding

CRC checksum calculation

Preamble

0 to 65536 bytes

Sync Word

0 to 8 bytes

Address

byte

Message

Up to 2047 bytes

CRC

2-bytes

Payload

(min 1 byte)

Fields added by the packet handler in Tx and processed and removed in Rx

Optional User provided fields which are part of the payload

Message part of the payload

Figure 33. Fixed Length Packet Format

Variable Length Packet Format

Variable length packet format is selected when bit PacketFormat is set to 1.

This mode is useful in applications where the length of the packet is not known in advance and can vary over time. It is then

necessary for the transmitter to send the length information together with each packet in order for the receiver to operate

properly.

In this mode the length of the payload, indicated by the length byte, is given by the first byte of the FIFO and is limited to

255 bytes. Note that the length byte itself is not included in its calculation. In this mode, the payload must contain at least 2

bytes, i.e. length + address or message byte.

An illustration of a variable length packet is shown below. It contains the following fields:

 Preamble (1010...)

 Sync word (Network ID)

 Length byte

 Optional Address byte (Node ID)

 Message data

RF98 bảng dữ liệu(PDF) 68 Page - HOPE Microelectronics CO., Ltd.