Module rx 

Reading packets out of the concentrator.

Received packets arrive in one buffer, back to back, each wrapped in metadata the chip writes around it: a sync word and nine bytes saying how long the payload is and how it was demodulated, then the payload, then fourteen more bytes of what the receiver made of it.

The metadata is in two halves and they are addressed differently. Everything before the payload is counted from the start of the packet; everything after it is counted from the start plus the payload length, which is why a reader has to know how long the payload is before it can find the signal levels or the timestamp.

A packet can also carry fine timestamp metrics after all of that, two bytes each, and the count lives in the tail. A reader that ignores them finds the next packet in the wrong place, so packet_len takes them into account and the walk in packets stays aligned.

Nothing here reads a register. A buffer is bytes, and this turns those bytes into packets, so a capture from a working gateway can be replayed and checked without hardware.

Structs

Packet

A packet as the concentrator wrote it into the buffer.

Quality

What the receiver made of a packet it heard.

Enums

Modem

Which demodulator heard a packet.

RxError

Why a buffer did not read as a packet.

Constants

BUFFER_LEN

How many bytes the receive buffer holds in all.

FSK_MODEM

The identifier of the frequency shift keying demodulator.

HEAD_METADATA

How many bytes of metadata come before the payload, the sync word included.

LORA_MULTI_MODEM_MAX

The highest identifier belonging to a multi-spreading-factor LoRa demodulator.

LORA_STD_MODEM

The identifier of the single-spreading-factor LoRa demodulator.

MAX_PAYLOAD

The largest payload a packet carries.

METRIC_LEN

How many bytes each fine timestamp metric takes.

SYNC_BYTE_0

The first byte of the word that marks the start of a packet.

SYNC_BYTE_1

The second byte of that word.

TAIL_METADATA

How many bytes of metadata come after it, before any timestamp metrics.

Functions

packet_len

How many bytes a packet takes in the buffer.

packets

Walks every packet the buffer holds, in the order the chip wrote them.

parse

Reads the one packet that starts at the front of these bytes.