mqx.h File Reference

Include dependency graph for mqx.h:

API Description

The mqx gas sensor driver can be used to read a wide range of sensors. The list below shows the currently supported sensors:

 mq2: H2/LPG/CH4/CO/alcohol/smoke/propane/etc
     LPG/propane 200-5000 ppm
     butane 300-5000 ppm
     CH4 5000-2000 ppm
     H2 300-5000 ppm
     alcohol 100-2000 ppm
 mq3: Alcohol/benzine/CH4/hexane/LPG/CO .05-10 mg/L
 mq4: CNG (mostly methane) 200-10000 ppm
 mq5: H2/LPG/CH4/CO/alcohol 200-10000 ppm
 mq6: LPG (mostly propane/butane) 200-10000 ppm
 mq7: CO 20-2000 ppm
 mq8: H 100-10000 ppm
 mq9: CO/CH4/LPG 200-1000/10000/10000 ppm

/*
 * Author: Noel Eck <noel.eck@intel.com>
 * Copyright (c) 2016 Intel Corporation.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <unistd.h>
#include <signal.h>

#include "mqx.h"
#include "upm_utilities.h"

bool shouldRun = true;

void sig_handler(int signo)
{
    if (signo == SIGINT)
        shouldRun = false;
}

int main()
{
    signal(SIGINT, sig_handler);


    // Instantiate a mqx sensor on analog pin A0
    mqx_context sensor = mqx_init(0);

    if (!sensor)
    {
        printf("mqx_init() failed.\n");
        return -1;
    }

    // Set the aref, scale, and offset
    mqx_set_aref(sensor, 5.0);
    mqx_set_scale(sensor, 1.0);
    mqx_set_offset(sensor, -.1);
    printf("aRef: %0.03f scale: %0.03f offset: %0.03f\n\n",
            mqx_get_aref(sensor),
            mqx_get_scale(sensor),
            mqx_get_offset(sensor));

    // Every half a second, sample the sensor output
    while (shouldRun)
    {
        float normalized = 0.0;
        float raw_volts = 0.0;
        float volts = 0.0;

        mqx_get_normalized(sensor, &normalized);
        mqx_get_raw_volts(sensor, &raw_volts);
        mqx_get_volts(sensor, &volts);

        printf("Normalized output: %0.03f, raw mqx sensor output: %0.03f v "
                "adjusted output: %0.03f v\n", normalized, raw_volts, volts);

        upm_delay_ms(500);
    }


    printf("Exiting\n");

    mqx_close(sensor);

    return 0;
}

Go to the source code of this file.

Data Structures
struct	_mqx_context

Functions
mqx_context	mqx_init (int16_t pin)
void	mqx_close (mqx_context dev)
upm_result_t	mqx_set_aref (const mqx_context dev, float aref)
upm_result_t	mqx_set_scale (const mqx_context dev, float scale)
upm_result_t	mqx_set_offset (const mqx_context dev, float offset)
float	mqx_get_aref (const mqx_context dev)
float	mqx_get_scale (const mqx_context dev)
float	mqx_get_offset (const mqx_context dev)
upm_result_t	mqx_get_normalized (const mqx_context dev, float *value)
upm_result_t	mqx_get_raw_volts (const mqx_context dev, float *value)
upm_result_t	mqx_get_volts (const mqx_context dev, float *value)

Typedefs
typedef struct _mqx_context *	mqx_context

Function Documentation

mqx_context mqx_init

(

int16_t

pin

)

Initialize analog sensor

Parameters

pin	Analog pin

Returns

sensor context

void mqx_close

(

mqx_context

dev

)

Analog sensor destructor

Parameters

sensor

context pointer

upm_result_t mqx_set_aref	(	const mqx_context	dev,
		float	aref
	)

Set ADC reference voltage

Parameters

dev	sensor context pointer
aref	ADC reference voltage

Returns

Function result code

upm_result_t mqx_set_scale	(	const mqx_context	dev,
		float	scale
	)

Set sensor scale. This scale is applied to the return value: counts = counts * scale

Parameters

dev	sensor context pointer
scale	count scale value used

Returns

Function result code

upm_result_t mqx_set_offset	(	const mqx_context	dev,
		float	offset
	)

Set sensor offset. This offset is applied to the return value: counts = counts + offset

Parameters

dev	sensor context pointer
offset	count offset value used

Returns

Function result code

float mqx_get_aref

(

const mqx_context

dev

)

Get sensor aref

Parameters

dev	sensor context pointer

Returns

Sensor ADC reference voltage

float mqx_get_scale

(

const mqx_context

dev

)

Get sensor scale

Parameters

dev	sensor context pointer

Returns

Sensor scale

float mqx_get_offset

(

const mqx_context

dev

)

Get sensor offset

Parameters

dev	sensor context pointer

Returns

Sensor offset

upm_result_t mqx_get_normalized	(	const mqx_context	dev,
		float *	value
	)

Read normalized value for sensor

Parameters

dev	sensor context pointer
*value	Normalized value (0.0 -> 1.0)

Returns

Function result code

upm_result_t mqx_get_raw_volts	(	const mqx_context	dev,
		float *	value
	)

Read raw voltage from the sensor

Parameters

dev	sensor context pointer
*value	Raw sensor voltage

Returns

Function result code

upm_result_t mqx_get_volts	(	const mqx_context	dev,
		float *	value
	)

Read scaled/offset voltage from the sensor

Parameters

dev	sensor context pointer
*value	Adjusted sensor voltage

Returns

Function result code

Typedef Documentation

typedef struct _mqx_context * mqx_context

driver context