Noel Eck fe318a78d2 mqx: C gas sensors mq2-mq9
Implement a single source file for the following:

    * mq2: H2/LPG/CH4/CO/alcohol/smoke/propane/etc
    * mq3: Alcohol/benzine/CH4/hexane/LPG/CO
    * mq4: CNG (mostly methane)
    * mq5: H2/LPG/CH4/CO/alcohol
    * mq6: LPG (mostly propane/butane)
    * mq7: CO
    * mq8: H
    * mq9: CO/CH4/LPG

The documentation for these sensors notes that they do not read an exact
gas concentration.  Some of the sensors have examples for how to
calibrate with a 'clean air environment' for outputing ppm, but this is
not the case for all mqx sensors.  Because of this, the output can be
read as a normalized output (0.0->1.0), raw volts (normalized * aRef),
or a scaled/offset voltage.

Signed-off-by: Noel Eck <noel.eck@intel.com>
2016-09-14 14:08:56 -07:00
..
2016-09-14 14:08:56 -07:00
2016-09-14 14:08:56 -07:00
2016-09-14 14:08:56 -07:00
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2014-12-02 16:35:55 +00:00

Grove - Gas Sensor(MQ-2):Combustible Gas Smoke [medium sensitivity]
Grove - Gas Sensor(MQ-3):Alcohol and Benzine [high sensitivity] Long warm-up
Grove - Gas Sensor(MQ-5):LPG, Natural Gas, Town Gas [high sensitivity]
Grove - Gas Sensor(MQ-9):LPG, CO, CH4 [low sensitivity]
Grove - Air Quality Sensor(TP-401): CO, alcohol, acetone, thinner, others [high sensitivity].

Note - Gas sensors need to be heated, first minute the data is incorrect. Air
Quality sensor needs 48h to stabilize.