API for the MQ2 Gas Sensor. More...

Detailed Description

ID: mq2
Name: MQ2 Methane, Butane, Liquefied Petroleum Gas (LPG), and Smoke Sensor
Category: gaseous
Manufacturer: seeed
Connection: analog
Kit: hak
Link: http://wiki.seeed.cc/Grove-Gas_Sensor-MQ2/

The MQ2 Gas Sensor module is useful for gas leakage detection (in home and industry). It can detect LPG, i-butane, methane, alcohol, hydrogen, smoke, and other combustible gases. It's a medium-sensitivity sensor with a detection range of 300-10,000 ppm.

int
main(int argc, char** argv)
{
    // Attach gas sensor to A0
    upm::MQ2 sensor(0);
    signal(SIGINT, sig_handler);
    thresholdContext ctx;
    ctx.averageReading = 0;
    ctx.runningAverage = 0;
    ctx.averagedOver = 2;
    // Infinite loop, ends when script is cancelled
    // Repeatedly, take a sample every 2 milliseconds;
    // find the average of 128 samples; and
    // print a running graph of the averages using a resolution of 5
    while (!is_running) {
        int len = sensor.getSampledWindow(2, 128, buffer);
        if (len) {
            int thresh = sensor.findThreshold(&ctx, 30, buffer, len);
            sensor.printGraph(&ctx, 5);
            if (thresh) {
                // do something ....
            }
        }
    }
    std::cout << "exiting application" << std::endl;
    return 0;
}

Public Member Functions
	MQ2 (int gasPin)

	~MQ2 ()

std::string	name ()

Public Member Functions inherited from Gas
	Gas (int gasPin)

virtual	~Gas ()

virtual int	getSampledWindow (unsigned int freqMS, int numberOfSamples, uint16_t *buffer)

virtual int	findThreshold (thresholdContext ctx, unsigned int threshold, uint16_t buffer, int len)

virtual int	getSampledData (thresholdContext *ctx)

virtual int	getSample ()

virtual void	printGraph (thresholdContext *ctx, uint8_t resolution)