Payload Utilities

Data Structures
struct	scd30_meas_t
	SCD30 CO₂, temperature, and humidity measurement. More...
struct	veml7700_meas_t
	VEML7700 ambient light level measurement. More...
struct	bme280_meas_t
	BME280 temperature, humidity and pressure measurement. More...
struct	sensor_payload_t
	Aggregated payload holding measurements from all sensors. More...

Functions
pal_err_t	pl_set_scd30_data (sensor_payload_t *restrict pl, const scd30_meas_t *restrict data)
	Copy SCD30 measurement data into a sensor payload.
pal_err_t	pl_set_veml7700_data (sensor_payload_t *restrict pl, const veml7700_meas_t *restrict data)
	Copy VEML7700 measurement data into a sensor payload.
pal_err_t	pl_set_bme280_data (sensor_payload_t *restrict pl, const bme280_meas_t *restrict data)
	Copy BME280 measurement data into a sensor payload.

Detailed Description

Copyright

Copyright (c) 2026 Adrien Chevrier. Under AGPL-3.0-or-later license.

Provides measurement structures for each supported sensor and helper functions to copy their data into a unified payload strucuture ready for transmission.

Todo

Add relevant identification metadata to the sensor payload structure so that it would be possible to know when measurements were taken.

Warning

The current sensor payload implementation writes the sensor struct directly into the packet payload as-is, without any byte-by-byte packing as described in the protocol. This makes it sensitive to the platform endianness (little-endian).

Todo

Rewrite the sensor payload structure and packing processes to store each field byte by byte instead of copying the raw data struct, as recommended by the protocol.

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Data Structure Documentation

scd30_meas_t

struct scd30_meas_t

SCD30 CO₂, temperature, and humidity measurement.

Data Fields
float	co2	CO₂ concentration [ppm].
float	rh	Relative humidity [%].
float	t	Temperature [°C].

veml7700_meas_t

struct veml7700_meas_t

VEML7700 ambient light level measurement.

Data Fields
uint32_t	als	Ambient light level [lx].

bme280_meas_t

struct bme280_meas_t

BME280 temperature, humidity and pressure measurement.

Data Fields
float	p	Atmospheric pressure [hPa].
float	rh	Relative humidity [%].
float	t	Temperature [°C].

sensor_payload_t

struct sensor_payload_t

Aggregated payload holding measurements from all sensors.

Fields are populated individually via the pl_set_*_data() helpers.

Data Fields
uint32_t	als_veml7700	VEML7700 ambient light level [lx].
float	co2_scd30	SCD30 CO₂ concentration [ppm].
float	p_bme280	BME280 atmospheric [hPa].
float	rh_bme280	BME280 relative humidity [%].
float	rh_scd30	SCD30 relative humidity [%].
float	t_bme280	BME280 temperature [°C].
float	t_scd30	SCD30 temperature [°C].

Function Documentation

pl_set_bme280_data()

pal_err_t pl_set_bme280_data	(	sensor_payload_t *restrict	pl,
		const bme280_meas_t *restrict	data )

Copy BME280 measurement data into a sensor payload.

Parameters

[in,out]	pl	Pointer to the payload to update.
[in]	data	Pointer to the BME280 measurement to copy from.

Return values

PAL_OK	On success.
PAL_ERR_INVALID_ARG	Any pointer is NULL.

pl_set_scd30_data()

pal_err_t pl_set_scd30_data	(	sensor_payload_t *restrict	pl,
		const scd30_meas_t *restrict	data )

Copy SCD30 measurement data into a sensor payload.

Parameters

[in,out]	pl	Pointer to the payload to update.
[in]	data	Pointer to the SCD30 measurement to copy from.

Return values

PAL_OK	On success.
PAL_ERR_INVALID_ARG	Any pointer is NULL.

pl_set_veml7700_data()

pal_err_t pl_set_veml7700_data	(	sensor_payload_t *restrict	pl,
		const veml7700_meas_t *restrict	data )

Copy VEML7700 measurement data into a sensor payload.

Parameters

[in,out]	pl	Pointer to the payload to update.
[in]	data	Pointer to the VEML7700 measurement to copy from.

Return values

PAL_OK	On success.
PAL_ERR_INVALID_ARG	Any pointer is NULL.