Xadow - Multichannel Gas Sensor

Xadow – Multichannel Gas sensor is a very small sensor board with a compact MOS sensor, MiCS-6814.
The MiCS-6814 is a robust MEMS sensor for the detection of pollution from automobile exhausts and for
agricultural/industrial odors. This sensor board has two standard Xadow interfaces. It is very easy to
use with Xadow - Main Board.

Feature

Three fully independent sensing elements on one package
Built with ATmega168PA
I2C interface with programmable address
Heating power can be shut down for low power
Standard Xadow outline

Block Diagram

Electrical Characteristics

Item	Condition	Min.	Typ.	Max.	Unit
Voltage	-	3.1	3.3	3.5	V
Ripple	@Max Power	-	80	100	mV
Heating Power	-	-	-	88	mW
Max Power	-	-	-	150	mW
ADC Precision	-	-	10	-	Bits
ADC Voltage	-	0	-	3.3	V
I2C Rate	-	-	100	400	kHz
VIL	@I2C	-0.5	-	0.99	V
VIH	@I2C	2.31	-	3.8	V

Performance RED sensor

Characteristic RED sensor	Symbol	Typ	Min	Max	Unit
Sensing resistance in air	R0	-	100	1500	kΩ
Typical CO detection range	FS	-	1	1000	ppm
Sensitivity factor	SR	-	1.2	50	-

Performance OX sensor

Characteristic OX sensor	Symbol	Typ	Min	Max	Unit
Sensing resistance in air	R0	-	0.8	20	kΩ
Typical NO2 detection range	FS	-	0.05	10	ppm
Sensitivity factor	SR	-	2	-	-

Performance NH3 sensor

Characteristic NH3 sensor	Symbol	Typ	Min	Max	Unit
Sensing resistance in air	R0	-	10	1500	kΩ
Typical NH3 detection range	FS	-	1	300	ppm
Sensitivity factor	SR	-	1.5	15	-

Pin Definition

Demonstration

You can get start with Xadow - Main Board

Hardware Installation:

1) Connect Xadow - Multichannel Gas Sensor to Xadow - Main Board. Do not forget to install Xadow

Driver. Note: when connect Xadow - Multichannel Gas Sensor to Xadow - Main Board, you should concern about

the connection direction. The connection method is that the unfilled corner of one xadow module

need to connect to the right angle of another module(see four corners of each xadow module).

Upload Code:

2) Download Arduino Library & Grove/Xadow firmware and install it to Arduino Library.
3) Open the code directly by the path:File -> Example ->Mutichannel_Gas_Sensor->ReadSensorValue_Xadow.

The content of ReadSensorValue_Xadow.ino please refer to below.

/*
    This is a demo to test MutichannelGasSensor library
    This code is running on Xadow-mainboard, and the I2C slave is Xadow-MutichannelGasSensor
    There is a ATmega168PA on Xadow-MutichannelGasSensor, it get sensors output and feed back to master.
    the data is raw ADC value, algorithm should be realized on master.
    
    please feel free to write email to me if there is any question 
    
    Jacky Zhang, Embedded Software Engineer
    qi.zhang@seeed.cc
    17,mar,2015
*/

#include "xadow.h"
#include <Wire.h>
#include "MutichannelGasSensor.h"

void setup()
{
    Xadow.init();

    Serial.begin(9600);  // start serial for output
    Serial.println("power on!");

    mutichannelGasSensor.begin(0x04);//the default I2C address of the slave is 0x04
    //mutichannelGasSensor.changeI2cAddr(0x10);
    //mutichannelGasSensor.doCalibrate();
    //delay(8000);
    while(mutichannelGasSensor.readR0() < 0)
    {
        Serial.println("sensors init error!!");
        delay(1000);
    }
    Serial.print("Res0[0]: ");
    Serial.println(mutichannelGasSensor.res0[0]);
    Serial.print("Res0[1]: ");
    Serial.println(mutichannelGasSensor.res0[1]);
    Serial.print("Res0[2]: ");
    Serial.println(mutichannelGasSensor.res0[2]);
    mutichannelGasSensor.powerOn();
}

void loop()
{
    mutichannelGasSensor.readR();
    Serial.print("Res[0]: ");
    Serial.println(mutichannelGasSensor.res[0]);
    Serial.print("Res[1]: ");
    Serial.println(mutichannelGasSensor.res[1]);
    Serial.print("Res[2]: ");
    Serial.println(mutichannelGasSensor.res[2]);
    
    mutichannelGasSensor.calcGas();
    Serial.print("NH3: ");
    Serial.print(mutichannelGasSensor.density_nh3);
    Serial.println("ppm");
    Serial.print("CO: ");
    Serial.print(mutichannelGasSensor.density_co);
    Serial.println("ppm");
    Serial.print("NO2: ");
    Serial.print(mutichannelGasSensor.density_no2);
    Serial.println("ppm");
    
    Xadow.greenLed(LEDON);
    delay(500);
    Xadow.greenLed(LEDOFF);
    delay(500);
    Serial.println("...");
}

4) Upload the code. Remeber to select Seeeduino Xadow from the Tools | Board menu of the

Arduino environment, and select the correct serial port Xadow - Main Board is using. Or you could select Arduino Leonardo to instead of it.
By opening the serial monitor, you can see the raw data read from sensor.