mq303a: python example for mq303a alcohol sensor

Signed-off-by: Zion Orent <zorent@ics.com>
Signed-off-by: Mihai Tudor Panu <mihai.tudor.panu@intel.com>

examples/python/mq303a.py

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+#!/usr/bin/python
+# Author: Zion Orent <zorent@ics.com>
+# Copyright (c) 2015 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.
+
+import time, sys, signal, atexit
+
+# Load alcohol sensor module
+import pyupm_mq303a as upmMq303a
+
+# Instantiate an mq303a sensor on analog pin A0
+# This device uses a heater powered from an analog I/O pin. 
+# If using A0 as the data pin, then you need to use A1, as the heater
+# pin (if using a grove mq303a).  For A1, we can use the D15 gpio, 
+# setup as an output, and drive it low to power the heater.
+myAlcoholSensor = upmMq303a.MQ303A(0, 15)
+
+
+## Exit handlers ##
+# This function stops python from printing a stacktrace when you hit control-C
+def SIGINTHandler(signum, frame):
+	raise SystemExit
+
+# This function lets you run code on exit, including functions from myAlcoholSensor
+def exitHandler():
+	print "Exiting"
+	sys.exit(0)
+
+# Register exit handlers
+atexit.register(exitHandler)
+signal.signal(signal.SIGINT, SIGINTHandler)
+
+
+print "Enabling heater and waiting 2 minutes for warmup."
+
+# give time updates every 30 seconds until 2 minutes have passed
+# for the alcohol sensor to warm up
+def warmup(iteration):
+	totalSeconds = (30 * iteration)
+	time.sleep(30)
+	print totalSeconds, "seconds have passed"
+warmup(1)
+warmup(2)
+warmup(3)
+warmup(4)
+
+notice = ("This sensor may need to warm "
+"until the value drops below about 450.")
+print notice
+
+# Print the detected alcohol value every second
+while(1):
+	val = myAlcoholSensor.value()
+	msg = "Alcohol detected "
+	msg += "(higher means stronger alcohol): "
+	print msg + str(val)
+	time.sleep(1)