Downlink Encoding / Decoding¶

Include¶

Include the downlink header for downlink functionality:

#include <downlink.h>

void sfx_downlink_encode(sfx_dl_plain to_encode, sfx_commoninfo common, sfx_dl_encoded *encoded)¶

generate raw Sigfox downlink frame from given contents, for given Sigfox object and its state

Parameters

to_encode – content of raw Sigfox frame, only sfx_dl_plain::payload has to be set, all other members of sfx_dl_plain are ignored
common – general information about the Sigfox object and its state
encoded – output, raw Sigfox downlink frame, excluding preamble

void sfx_downlink_decode(sfx_dl_encoded encoded, sfx_commoninfo common, sfx_dl_plain *decoded)¶

retrieve contents of Sigfox downlink from given raw frame

Attention: This function applies Forward Error Correction (FEC). If FEC has occurred during decoding, sfx_dl_plain::fec_corrected will be set to true in the output.

Parameters

to_decode – the raw contents of the Sigfox downlink frame to decode
common – General information about the Sigfox object and its state. If a wrong NAK is provided, sfx_dl_plain::mac_ok will be false, but decoding will still work.
decoded – output, contents of Sigfox frame and whether MAC / CRC match

struct sfx_dl_plain¶

properties that describe the plain contents of a downlink frame after decoding or before encoding

Public Members

uint8_t payload[SFX_DL_PAYLOADLEN]¶: plaintext payload of downlink frame, always 8 bytes long

bool crc_ok¶: indicates whether CRC of downlink frame is valid, set by sfx_downlink_decode

bool mac_ok¶: indicates whether MAC of downlink frame is valid, set by sfx_downlink_decode

bool fec_corrected¶: indicates whether FEC was applied during decoding, set by sfx_downlink_decode

struct sfx_dl_encoded¶

properties that describe the encoded contents of a raw downlink frame after reception / before transmission

Public Members

uint8_t frame[SFX_DL_FRAMELEN]¶: raw, scrambled contents of downlink frame without preamble, 15 bytes long

The encoding / decoding functions handle downlinks excluding the preamble. However, the preamble content can be obtained from the following array:

uint8_t SFX_DL_PREAMBLE[]¶: content of Sigfox’s 13-byte (SFX_DL_PREAMBLELEN) downlink preamble