Datasheet SGP30 (Sensirion) - 9

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Air Quality Signals
SGP30 uses a dynamic baseline compensation algorithm and on-chip calibration parameters to provide two complementary air quality signals. Based on the sensor signals a total VOC signal (TVOC) and a CO2 equivalent signal (CO2eq) are calculated. Sending an “sgp30_iaq_init” command starts the air quality measurement. After the “sgp30_iaq_init” command, a “sgp30_measure_iaq” command has to be sent in regular intervals of 1s to ensure proper operation of the dynamic baseline compensation algorithm. The sensor responds with 2 data bytes (MSB first) and 1 CRC byte for each of the two preprocessed air quality signals in the order CO2eq (ppm) and TVOC (ppb). For the first 15s after the “sgp30_iaq_init” command the sensor is in an initialization phase during which a “sgp30_measure_iaq” command returns fixed values of 400 ppm CO2eq and 0 ppb TVOC. A new “sgp30_iaq_init” command has to be sent after every power-up or soft reset. The command sequence after start-up for initializing and repeating measurements is illustrated in
Figure 11
.
Figure 11
Command sequence for starting and repeating measurements. An example implementation of a generic driver can be found in the document SGP30 driver integration guide on Sensirion webpage.
Set and Get Baseline
The SGP30 also provides the possibility to read and write the baseline values of the baseline compensation algorithm. This feature is used to save the baseline in regular intervals on an external non-volatile memory and restore it after a new power-up or soft reset of the sensor. The command “sgp30_get_iaq_baseline” returns the baseline values for the two air quality signals. The sensor responds with 2 data bytes (MSB first) and 1 CRC byte for each of the two values in the order CO2eq and TVOC. These two values should be stored on an external memory. After a power-up or soft reset, the baseline of the baseline compensation algorithm can be restored by sending first an “sgp30_iaq_init” command followed by a “sgp30_set_iaq_baseline” command with the two baseline values as parameters in the order as (TVOC, CO2eq). An example implementation of a generic driver for the baseline algorithm can be found in the document SGP30 driver integration guide.
Inceptive Baseline for TVOC measurements9
The inceptive baseline offers an individually calibrated starting reference to the dynamic baseline compensation algorithm. Thereby the feature yields a better TVOC concentration accuracy for the very first start-up under bad air condition. This results in a better user experience especially when accuracy is required. Please note, that the application of this feature is solely limited to the very first start-up period of an SGP sensor. Furthermore, it is limited to the TVOC signal output. “sgp30_get_tvoc_inceptive_baseline” reads the precalibrated reference point from the sensor HW and “sgp30_set_tvoc_baseline” activates the inceptive baseline. Only use “sgp30_set_tvoc_baseline” when activating the inceptive baseline. 9 The inceptive baseline feature is available for SGP30 sensors with feature set 34 and later. www.sensirion.com Version 1.0 – May 2020 – D1 9/19 Document Outline 1 Sensor Performance 1.1 Gas Sensing Performance 1.2 Air Quality Signals 1.3 Recommended Operating and Storage Conditions 2 Electrical Specifications 3 Interface Specifications The SGP30 comes in a 6-pin DFN package, see Table 4. 4 Absolute Minimum and Maximum Ratings 5 Timing Specifications 5.1 Sensor System Timings 5.2 Communication Timings 6 Operation and Communication 6.1 Power-Up and Communication Start 6.2 Measurement Communication Sequence 6.3 Measurement Commands 6.4 Soft Reset 6.5 Get Serial ID 6.6 Checksum Calculation 6.7 Communication Data Sequences 7 Quality 7.1 Environmental Stability 7.2 Material Contents 8 Device Package 8.1 Moisture Sensitivity Level 8.2 Traceability 8.3 Package Outline 8.4 Landing Pattern 8.5 Soldering Instructions 9 Tape & Reel Package 10 Ordering Information Revision History Important Notices Warning, Personal Injury ESD Precautions Warranty Headquarters and Subsidiaries