Add skeleton for Encoder module to read eQEP

related to feature request in issue #122

Author: pdp7

Adafruit_BBIO/Encoder.py

@@ -0,0 +1,34 @@
+#!/usr/bin/python
+
+# ===========================================================================
+# Adafruit_BBIO.Encoder.QEP Class
+# ===========================================================================
+
+class QEP :
+
+  def __init__(self, channel=1, debug=False):
+    self.channel = channel
+    self.debug = debug
+
+  def errMsg(self):
+    print("Error accessing 0x%02X: Check your QEP channel" % self.address)
+    return -1
+
+# example method from Adafruit_I2C
+# TODO: delete this
+  def write8(self, reg, value):
+    "Writes an 8-bit value to the specified register/address"
+    try:
+      self.bus.write_byte_data(self.address, reg, value)
+      if self.debug:
+        print("Rotary: Wrote 0x%02X to register 0x%02X" % (value, reg))
+    except IOError as err:
+      return self.errMsg()
+
+
+if __name__ == '__main__':
+  try:
+    qep = Adafruit_BBIO.Encoder.QEP()
+    print("Default QEP channel is accessible")
+  except:
+    print("Error accessing default Rotary bus")