Ozone 2 Click

Featuring an accurate 22-bit ADC and a high-quality O₃ sensor protected by a stainless mesh, this Click board™ can be used in a range of applications used to measure or detect O₃ gas concentrations in the atmosphere, for small testing equipment development, various warning systems for air quality / ozone pollution, and other similar applications that are used for the ozone concentration detection and monitoring.

How does it work?

The main sensor component of the Ozone 2 click is the MQ131 ozone (O₃) gas sensor from Winsen Sensor, which uses the SnO2 (tin-oxide) alloy, which decreases its resistance while exposed to the O₃ gas. The greater the O₃ concentration is, the more conductive this material becomes. This can be utilized to obtain the O₃ concentration readings. The sensor itself contains a small heating element, connected to 5V power supply. It needs to be preheated for 48h before it can perform as specified. The sensitivity of the sensor is given as the ratio between the resistance in air and the resistance in the O₃ gas concentration of 50ppm, which is ≥ 3 (R_O/R_S ≥ 3). The sensor is protected against particles and mechanical damage by a stainless mesh, however, exposing to excessive moisture and corrosive gases can damage the inner structure.

Pinout diagram

This table shows how the pinout on Ozone 2 click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
Analog pin	AN	1	AN	PWM	16	NC
	NC	2	RST	INT	15	NC
SPI Chip Select	CS	3	CS	TX	14	NC
SPI clock	SCK	4	SCK	RX	13	NC
SPI Data OUT	SDO	5	MISO	SCL	12	NC
	NC	6	MOSI	SDA	11	NC
Power supply	+3.3V	7	3.3V	5V	10	+5V	Power supply
Ground	GND	8	GND	GND	9	GND	Ground

Onboard Jumpers and Settings

Software Support

We provide a library for Ozone 2 click on our LibStock page, as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.

Library Description

The library carries functions for initialization and reading the pa a digital value from MCP3351. Conversion of value to PPM is not covered by the library because it depends on the measurement environment.

Key functions

• uint32_t ozone2_read() – Reads a digital value from MCP3351 ADC circuit

Examples Description

The application is composed of three sections :

• System Initialization – GPIO and SPI module initialization
• Application Initialization – SPI Driver initialization
• Application Task – reading raw digital value from ADC each one second and displaying it via UART terminal

void applicationTask()
{
 readValue = ozone2_read();
 LongWordToStr(readValue,text);
 mikrobus_logWrite("Read Value: ",_LOG_TEXT);
 mikrobus_logWrite(text,_LOG_LINE);
 Delay_ms(1000);
}

Keep on mind that this is a raw measurement which should be converted to exact Ozone PPM value using formulas provided by circuit producer. Conversion to PPM depends on few conditions – more details
can be found in the datasheet.

The full application code, and ready to use projects can be found on our
LibStock page.

mikroE Libraries used in the example:

• UART
• SPI
• Conversions

Additional notes and information

Depending on the development board you are using, you may need USB UART click,  USB UART 2 click or  RS232 click to connect to your PC, for development systems with no UART to USB interface available on the board. The terminal available in all MikroElektronika compilers, or any other terminal application of your choice, can be used to read the message.

mikroSDK

This click board is supported with mikroSDK - MikroElektronika Software Development Kit. To ensure proper operation of mikroSDK compliant click board demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.

For more information about mikroSDK, visit the official page.