maxsonarez: Initial implementation

The module supports the LV-MaxSonar EZ1, EZ2, EZ3 and EZ4 ultrasonic
range finders.  It was developed and tested on the EZ3 variant.

Signed-off-by: Jon Trulson <jtrulson@ics.com>
Signed-off-by: Mihai Tudor Panu <mihai.tudor.panu@intel.com>

examples/python/maxsonarez.py

@@ -0,0 +1,60 @@
+#!/usr/bin/python
+# Author: Jon Trulson <jtrulson@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
+import pyupm_maxsonarez as MaxSonarEZ
+
+# Instantiate a MaxSonar-EZ on analog pin A1, with an analog
+# reference voltage of MAXSONAREZ_AREF
+Sonar = MaxSonarEZ.MAXSONAREZ(1)
+
+## Exit handlers ##
+# This stops python from printing a stacktrace when you hit control-C
+def SIGINTHandler(signum, frame):
+	raise SystemExit
+
+# This lets you run code on exit,
+# including functions from Sonar
+def exitHandler():
+	print "Exiting"
+	sys.exit(0)
+
+# Register exit handlers
+atexit.register(exitHandler)
+signal.signal(signal.SIGINT, SIGINTHandler)
+
+
+# analog voltage, usually 3.3 or 5.0
+MAXSONAREZ_AREF = 5.0;
+
+# Every second, sample the sonar and output the distance to an
+# object in inches.
+
+# With the EZ3 version, the minimum and maximum ranges seemed to be
+# between 6 and 33 inches
+
+while (1):
+	print "AREF: {0}, distance in inches: {1}".format(
+                MAXSONAREZ_AREF,
+                Sonar.inches())
+	time.sleep(1)