LJelect Sub GHz FSK/OOK Transceiver Module : Data Sheet : Page 51

LJ1269HC

Rev1.0 Page 51 Web: www.ljelect.com

Figure 33. Variable Length Packet Format

Unlimited Length Packet Format

Unlimited length packet format is selected when bit PacketFormat is set to 0 and PayloadLength is set to 0.

The user can then transmit and receive packet of arbitrary length and PayloadLength register is not used in Tx/Rx modes for

counting the length of the bytes transmitted/received. This mode is a replacement for the legacy buffered mode in RF63/RF64

transceivers.

In Tx the data is transmitted depending on the TxStartCondition bit. On the Rx side the data processing features like Address

filtering, Manchester encoding and data whitening are not available if the sync pattern length is set to zero (SyncOn = 0). The

filling of the FIFO in this case can be controlled by the bit FifoFillCondition. The CRC detection in Rx is also not supported in this

mode of the packet handler, however CRC generation in Tx is operational. The interrupts like CrcOk & PayloadReady are not

available either.

An unlimited length packet shown in is made up of the following fields:

 Preamble (1010...).

 Sync word (Network ID).

 Optional Address byte (Node ID).

 Message data

 Optional 2-bytes CRC checksum (Tx only)

Figure 34. Unlimited Length Packet Format