RFM219SW

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Similar to the buffer mode, the data are obtained by reading the FIFO. The packet handler provides various options of decoding

and validating the incoming data. This can further reduce the work load and user program size of the MCU.

Packet Type: Fixed Length

The fixed length means that the payload length is configured into the device and will not be changed during the transmission. The

RX and TX shall have the same payload length in this case. The payload contains the optional Node ID and the Data. The

maximum payload length is limited to the FIFO size which is 32 bytes.

Optional Manchester or

data-whitening decoding

Preamble

Configurable

1 - 4 bytes

Sync

Configurable

1 - 4 bytes

Node ID

Optional

1 byte

Data

Configurable

0 - 31 bytes

CRC

Optional

2 bytes

Payload/FIFO

CRC calculation

Figure 24. Fixed Length Packet Structure

Packet Type: Variable Length

The variable length means that the payload length can vary in different frames. In this case, an additional “Length” byte is given

as the part of the payload to indicate the payload length of the current frame. The maximum payload length can be indicated by

the Length byte is 31, because the Length byte itself is not included in the calculation. For example, if the Length byte indicates

that the payload is 31 bytes, and the Node ID is supported, it means that there will be 1 byte of Node ID and 30 bytes of Data

incoming.

If the Length byte indicates that the payload length is larger than 31, which exceeds the maximum size of the FIFO minus 1, the

current packet will be discarded by the device and the Data will not be shifted into the FIFO.

Optional Manchester or

data-whitening decoding

Preamble

Configurable

1 - 4 bytes

Sync

Configurable

1 - 4 bytes

Node ID

Optional

1 byte

Length

1 byte

Data

Configurable

0 - 30 bytes

CRC

Optional

2 bytes

Payload/FIFO

CRC calculation

Figure 25. Variable Length Packet Structure

For more details of the FIFO and configuring each component of the packet handler, please refer to the “AN138

5.10 Receiver Operation Control

Multiple options, which can be seen in “Table 10 – Operating Setting”, are available for the user to design different operating

behavior of the device. The main purpose of this is to save the power consumption of the system. It can be seen that the device

contains a sleep timer and a receive timer. Also, the device supports the well-known wake-on radio (WOR) operation. Please

refer to the document “AN138 RFM219SW Configuration Guideline” for the details introduction of the operation settings.