Ozone 2 click

Ozone 2 click carries an MQ131 sensor for Ozone (O₃). The sensor outputs an analog voltage, which is converted by the onboard MCP3551 22-bit ADC converter or it is sent to the microcontroller via AN pin on the mikroBUS™, depending on the position of ADC SEL. jumper. The click is designed to run on 5V power supply. It communicates with the target microcontroller over SPI interface or AN pin on the mikroBUS™ line.

Note: The click carries TXB0106 Voltage Translator. For selecting the interface voltage level, use the onboard jumper, and choose between the 3.3V and 5V. For more information, see the Jumpers and Settings table below.

MQ131 sensor features

MQ131 is a semiconductor sensor for Ozone (O_3). The gas sensing layer on the sensor unit is made of Tin dioxide, which has lower conductivity in clean air. The sensor’s conductivity is higher with the rising of the gas concentration. The sensor consists of micro Al₂O₃ ceramic tube, Tin dioxide sensitive layer, measuring electrode and heater fixed into stainless steel net. The heater provides necessary conditions for the proper functioning of the sensitive components.

Calibrating the sensor

To calibrate the sensor for the environment you’ll be using it in, Ozone 2 click has a small potentiometer that allows you to adjust the Load Resistance of the sensor circuit. For precise calibration, the sensor needs to preheat (once powered up, it takes 48h to reach the right temperature).

Specifications

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
MCP3551 chip select	CS	3	CS	TX	14	NC
SPI clock pin	SCK	4	SCK	RX	13	NC
SPI slave data out pin	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

Jumpers and settings

LEDs, Buttons, Switches, Connectors, etc.

Programming

Code examples for Ozone 2 click, written for MikroElektronika hardware and compilers are available on Libstock.

Code snippet

The following code snippet outputs data from Ozone 2 click ADC reader via UART

01: void Ozone_2_Task()
02: {
03: uint32_t readValue;
04: uint8_t loggerTxt [40];
05: readValue = OZONE2_Read();
06: LongToStr(readValue, loggerTxt);
07: UART1_write_text("rnRead value:");
08: UART1_write_text(loggerTXT);
09: 
10: delay_ms(1000);
11: }