Air quality 4 click
PID: MIKROE-2896
Weight: 25 g
Air quality 4 click is an advanced air quality sensing device that combines multiple metal-oxide
sensing elements on a chip to provide detailed information of the air quality parameters. This
click can output a TVOC value readings as well as the CO2 equivalent concentration readings in
an indoor environment. Besides these compensated attributes, the click can also output raw
values of H2 and Ethanol in the air, that can be used to calculate gas concentrations, relative to a
reference concentration.
The sensor used on Air quality 4 click is actually a complete system of sensors on a chip,
featuring I2C interface, a temperature controlled micro hotplate, and two compensated and
processed indoor air quality signals. It is produced using the proprietary CMOSens® technology,
which provides very detailed information and robustness against air contamination. These
attributes make Air quality 4 click a perfect solution for various air conditioning systems,
ventilation systems and other IoT applications where accurate, detailed and reliable air quality
readings are required.
How does it work?
The sensor IC used on Air quality 4 click, is the SGP30 from Sensirion, a multi-pixel gas sensor
for indoor applications. This sensor is actually a system of several metal-oxide sensing elements
on a chip (pixels), used to measure and process readings of various gasses in the air and output
them in a form of two complementary air quality readings - Total Volatile Organic Compounds
(TVOC) [ppb] and CO2 equivalent signal [ppm].
The traditional metal-oxide (MOX) sensors suffer from sensitivity and responsiveness
degradation, after being exposed to siloxanes over time. Siloxanes are specific compounds
commonly found in the air, which negatively affect the MOX sensors. To overcome this
problem, the SGP30 sensors are made by utilizing the advanced MOXSens® Technology, which
provides these sensors with the unmatched robustness against siloxanes contamination. This
results with unprecedented long-term stability and accuracy.
The SGP30 uses a dynamic baseline compensation algorithm and calibration parameters, to
provide accurate readings of TVOC and CO2eq properties. These baseline values of the
compensation algorithm can be stored externally and read back into the device with the
appropriate I2C commands and can be used in an event of power down or restart. For the first 15
seconds after the I2C initialization command, the sensor is in an initialization phase of collecting
sensor measurements and baseline compensation data and will return fixed values of 400 ppm
CO2eq and 0 ppb TVOC, when measurement command is attempted.
The device also allows air humidity corrections over the results for both the compensated and
raw values. However, an absolute humidity sensor should be used for obtaining the humidity
reading. Readings from SHT click or any other similar humidity measuring device can be used
for this purpose. The appropriate I2C command will store the value into the on-chip memory and
perform the corrections, accordingly.
There are additional components on Air quality 4 click, that are used to provide necessary
voltage levels for the SGP30 sensor IC. This sensor uses not so common voltage level of 1.8V,
so to provide a proper communication with 3.3V and 5V capable MCUs, a small LDO voltage
regulator has to be used, along with the level shifter, which provides required logic voltage
levels. The SPX3819M5, a small 500mA LDO voltage regulator is used to provide the power
supply of 1.8V for the SGP30. For the level shifting, the PCA9306 dual bidirectional I2C bus
and SMBus voltage level shifter is used. This level shifter IC allows shifting (converting) the I2C
signal levels to the voltage level selected by the VCC SEL onboard SMD jumper. This allows
both 3.3V and 5V capable MCUs to be interfaced with the Air quality 4 click.
More detailed information about all the available I2C commands can be found in the SGP30
datasheet. However, all the functions and commands necessary to perform air quality readings,
as well as functions used to calculate H2 and Ethanol concentration levels, are contained within
the Air quality 4 click libraries, provided with this click board™. Their usage is demonstrated in
the included example application, which can be used as a reference for a custom application
design.
Specifications
Applications
A perfect solution for various air conditioning systems, ventilation systems and
other IoT applications where accurate, detailed and reliable air quality readings
are required.
SGP30 from Sensirion, a multi-pixel gas sensor, SPX3819M5, a small 500mA LDO
voltage regulator from EXAR, PCA9306 dual bidirectional I2C bus and SMBus
voltage level shifter from Texas Instruments
This device combines multiple metal-oxide sensing elements on a chip to
provide detailed information of the air quality parameters. SGP30 sensor is
manufactured with the proprietary MOXSens® Technology that ensures unique
long-term stability and accuracy.
I2C
3.3V or 5V
L (57.15 x 25.4 mm)
On-board modules
Key Features
Interface
Input Voltage
Click board size
Pinout diagram
This table shows how the pinout on Air quality 4 click corresponds to the pinout on the
mikroBUS™ socket (the latter shown in the two middle columns).
Notes
NC
NC
NC
NC
NC
NC
Power supply
Ground
+3.3V
GND
Pin
1
2
3
4
5
6
7
8
AN
RST
CS
SCK
MISO
MOSI
3.3V
GND
PWM
INT
RX
TX
SCL
SDA
5V
GND
16
15
14
13
12
11
10
9
Pin
NC
NC
NC
NC
SCL
SDA
+5V
GND
I2C Clock
I2C Data
Power supply
Ground
Notes
Air quality 4 click electrical specifications
Description
Measurement range of H2 and Ethanol
Sampling frequency of H2 and Ethanol
Measurement range of TVOC
Measurement range of CO2eq
Sampling frequency of TVOC and CO2eq
I2C clock frequency
0
0
400
1
400
Min
0
Typ
Max
1000
40
60000
60000
Unit
ppm
Hz
ppb
ppm
Hz
kHz
Onboard settings and indicators
Label Name Default
LD1
PWR
-
Left
Description
Power LED indicator
Voltage level selection, left position 3.3V, right 5V
JP1 VCC SEL
Software support
We provide a library for Air quality 4 click on our LibStock page, as well as a demo application
(example), developed using MikroElektronika compilers and mikroSDK. The provided click
library is mikroSDK standard compliant. The demo application can run on all the main
MikroElektronika development boards.
Library Description
Initializes and defines I2C bus driver and driver functions which perform measurements of H2,
TVOC, CO2 and EthOH (Ethanol) concentration in the air. Check the documentation for more
details.
Key functions
void air_quality4_measureQuality(uint8_t *readAir)
- The function writes 6 bytes
CO2 data (2 bytes) and TVOC data (2 bytes) with CRC data for each of them to a buffer, pointed
by the function parameter.
void air_quality4_getCO2AndTVOC(uint16_t *value)
- The function writes 2 bytes CO2
data and 2 bytes TVOC data without CRC data to a buffer, pointed by the function parameter.
void air_quality4_measureSignal(uint8_t *readAir)
- The function writes 6 bytes H2
data (2 bytes) and EthOH - Ethanol data (2 bytes) with CRC data for each of them to a
buffer, pointed by the function parameter.
void air_quality4_getH2AndEthOH(uint16_t *value)
- The function writes 2 bytes of H2
data and 2 bytes of EthOH data without CRC data to a buffer, pointed by the function parameter.
Examples Description
•
•
System Initialization - Initializes peripherals and pins. Application Initialization - Initializes click
driver and gets ID data.
Application Task - Performs measurements of air concentration for H2, EthOH(Ethanol), CO2 and
TVOC data. Results of the measurement are output to the UART.
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