Device driver interface for the Sensirion SGP30 Gas Sensor. More...

Detailed Description

Device driver interface for the Sensirion SGP30 Gas Sensor.

About

This driver provides an interface for the Sensirion SGP30 Gas Sensor. The Datasheet can be found here

After the sensor is powered up and starts measuring air quality for the first 15s sgp30_read_measurements calls will return fixed values of of 400ppm CO2eq and 0ppb TVOC. Afterwards values should be read in regular intervals of 1s for best operation of the dynamic baseline compensation algorithm.

The above is not done by default unless the sgp30_strict module is included. In that case, if attempting to read before the is completed, then -EAGAIN will be returned. After this periodic readings happen every 1s, and the last value read is returned when calling sgp30_read_measurements. A timestamp is also added to sgp30_data_t.

The sensor features on-chip humidity compensation for the air quality measurements. sgp30_set_absolute_humidity can be used to change the absolute humidity value used. See [SGP30 driver integration] (https://files.seeedstudio.com/wiki/Grove-VOC_and_eCO2_Gas_Sensor-SGP30/res/Sensirion_Gas_Sensors_SGP30_Driver-Integration-Guide_HW_I2C.pdf) for more on this. The baseline values for the correction algorithm can also be tweaked with sgp30_set_baseline. More on how to implement dynamic baseline compensation can be seen at [SGP30 driver integration] (https://files.seeedstudio.com/wiki/Grove-VOC_and_eCO2_Gas_Sensor-SGP30/res/Sensirion_Gas_Sensors_SGP30_Driver-Integration-Guide_HW_I2C.pdf).

Files
file	sgp30.h

file	sgp30_constants.h
	Internal addresses, registers and constants.

file	sgp30_params.h
	Default configuration.

Data Structures
struct	sgp30_data_t
	Set of measured values. More...

struct	sgp30_raw_data_t
	Set of measured raw values. More...

struct	sgp30_params_t
	Device initialization parameters. More...

struct	sgp30_t
	Device descriptor for the driver. More...

Functions
int	sgp30_init (sgp30_t dev, const sgp30_params_t params)
	Initialize the given device.

int	sgp30_start_air_quality (sgp30_t *dev)
	Start air quality measurements, called on sgp30_init.

int	sgp30_read_future_set (sgp30_t dev, uint16_t version)
	Initialize the given device.

int	sgp30_reset (sgp30_t *dev)
	Performs a soft reset on the device.

bool	sgp30_ready (sgp30_t *dev)
	If device is ready to start reading measurements.

int	sgp30_read_serial_number (sgp30_t dev, uint8_t buf, size_t len)
	Read the serial number from the sensor.

int	sgp30_read_measurements (sgp30_t dev, sgp30_data_t data)
	Read air quality signals.

int	sgp30_set_absolute_humidity (sgp30_t *dev, uint32_t humidity)
	Set absolute humidity value for on-chop humidity compensation.

int	sgp30_set_baseline (sgp30_t dev, sgp30_data_t data)
	Set new baseline values.

int	sgp30_get_baseline (sgp30_t dev, sgp30_data_t data)
	Returns baseline values.

int	sgp30_read_raw_measurements (sgp30_t dev, sgp30_raw_data_t data)
	Read raw signals H2 (sout_H2) and Ethanol(sout_EthOH)

Function Documentation

◆ sgp30_get_baseline()

int sgp30_get_baseline	(	sgp30_t *	dev,
		sgp30_data_t *	data
	)

Returns baseline values.

Parameters

[in]	dev	Device descriptor of the driver
[out]	data	Current baseline values

Return values

0	Success
-EBADMSG	CRC checksum didn't match
-EPROTO	Sensor did not acknowledge command

◆ sgp30_init()

int sgp30_init	(	sgp30_t *	dev,
		const sgp30_params_t *	params
	)

Initialize the given device.

Parameters

[in,out]	dev	Device descriptor of the driver
[in]	params	Initialization parameters

Returns: 0 on success

◆ sgp30_read_future_set()

int sgp30_read_future_set	(	sgp30_t *	dev,
		uint16_t *	version
	)

Initialize the given device.

Parameters

[in]	dev	Device descriptor of the driver
[out]	version	The future set version

Return values

0	Success
-EBADMSG	CRC checksum didn't match
-EPROTO	Sensor did not acknowledge command

◆ sgp30_read_measurements()

int sgp30_read_measurements	(	sgp30_t *	dev,
		sgp30_data_t *	data
	)

Read air quality signals.

Note: For the first 15s after the “Init_air_quality” command (called in the init function) the sensor is in an initialization phase during which a “Measure_air_quality” command returns fixed values of 400ppm CO2eq and 0ppb TVOC.

Parameters

[in]	dev	Device descriptor of the driver
[out]	data	Air quality measurements

Return values

0	Success
-EAGAIN	Sensor is not yet ready
-EBADMSG	CRC checksum didn't match
-EPROTO	Sensor did not acknowledge command

◆ sgp30_read_raw_measurements()

int sgp30_read_raw_measurements	(	sgp30_t *	dev,
		sgp30_raw_data_t *	data
	)

Read raw signals H2 (sout_H2) and Ethanol(sout_EthOH)

It returns the sensor raw sensor signals which are used as inputs for the on-chip calibration and baseline compensation algorithms.

Parameters

[in]	dev	Device descriptor of the driver
[out]	data	Raw measurement values

Return values

0	Success
-EBADMSG	CRC checksum didn't match
-EPROTO	Sensor did not acknowledge command

◆ sgp30_read_serial_number()

int sgp30_read_serial_number	(	sgp30_t *	dev,
		uint8_t *	buf,
		size_t	len
	)

Read the serial number from the sensor.

Parameters

[in]	dev	Device descriptor of the driver
[out]	buf	Pre-allocated memory for returning the serial number
[in]	len	Length of the `str` buffer, must be 6

Return values

0	Success
-EBADMSG	CRC checksum didn't match
-EPROTO	Sensor did not acknowledge command

◆ sgp30_ready()

bool sgp30_ready ( sgp30_t * dev )

If device is ready to start reading measurements.

Note: Only available if sgp30_strict is used

Parameters

[in] dev Device descriptor of the driver

Return values

true	If ready to read measurements
false	If still in warm-up period of it sgp30_start_air_quality has not been called

◆ sgp30_reset()

int sgp30_reset ( sgp30_t * dev )

Performs a soft reset on the device.

Warning: Reset is performed via a "General Call". All devices on the same I2C bus that support the General Call mode will perform a reset.

Parameters

[in] dev Device descriptor of the driver

Return values

0	Success
-PROTO	Sensor did not acknowledge command

◆ sgp30_set_absolute_humidity()

int sgp30_set_absolute_humidity	(	sgp30_t *	dev,
		uint32_t	humidity
	)

Set absolute humidity value for on-chop humidity compensation.

Note: This function requires absolute humidity values, most sensors output relative humidity, this can be calculated if temperature is also known:

AH = 216.7 * ((RH / 100.0) * 6.112 * exp(17.62 * T / (243.12 + T))) / (273.15 + T)

Where RH is in 0-100%, and T is in C.

(*) Approximation formula from Sensirion SGP30 Driver Integration chapter 3.15

Parameters

[in]	dev	Device descriptor of the driver
[in]	humidity	Humidity in mg/m3 units. A values of 0 disables humidity compensation, max value is 255999 mg/m3.

Return values

0	Success
-PROTO	Sensor did not acknowledge command

◆ sgp30_set_baseline()

int sgp30_set_baseline	(	sgp30_t *	dev,
		sgp30_data_t *	data
	)

Set new baseline values.

Parameters

[in]	dev	Device descriptor of the driver
[in]	data	Baseline values to be set

Return values

0	Success
-PROTO	Sensor did not acknowledge command

◆ sgp30_start_air_quality()

int sgp30_start_air_quality ( sgp30_t * dev )

Start air quality measurements, called on sgp30_init.

Note: Must be called after every power-cycle or soft reset.

Parameters

[in,out] dev Device descriptor of the driver

Return values

0	Success
-PROTO	Sensor did not acknowledge command

Detailed Description

About

Files

Data Structures

Functions

Function Documentation

◆ sgp30_get_baseline()

◆ sgp30_init()

◆ sgp30_read_future_set()

◆ sgp30_read_measurements()

◆ sgp30_read_raw_measurements()

◆ sgp30_read_serial_number()

◆ sgp30_ready()

◆ sgp30_reset()

◆ sgp30_set_absolute_humidity()

◆ sgp30_set_baseline()

◆ sgp30_start_air_quality()