added a square waveform generator

Author: brentru

adafruit_waveform/square.py

@@ -0,0 +1,39 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
+#
+# 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.
+"""
+`adafruit_waveform`
+====================================================
+
+TODO(description)
+
+* Author(s): Scott Shawcroft, BrentRu
+"""
+
+import array
+
+
+def square_wave(sample_length = 2):
+    """Generate a single square wave of sample_length size"""
+    s = array.array("H", [0] * sample_length)
+    for i in range(sample_length / 2):
+        s[i] = 0xFFFF
+    return s