Encoder: improved usage documentation

Author: dplanella

Adafruit_BBIO/README.md

@@ -7,21 +7,57 @@ This module enables access to the Beaglebone Black enhanced Quadrature Encoder P
 On a recent Beaglebone Debian image, access to the eQEP0 and eQEP2 channels should work out of the box:
 
 ```python
-import Adafruit_BBIO.Encoder as Encoder
+from Adafruit_BBIO.Encoder import RotaryEncoder, eQEP2
 
 '''
 Each channel can be accessed and initialized using its corresponding
 channel name constants:
 
-    Encoder.eQEP0
-    Encoder.eQEP1  # Pins only available when video is disabled
-    Encoder.eQEP2
-    Encoder.eQEP2b # Pins only available when video is disabled
+    eQEP0
+    eQEP1  # Pins only available when video is disabled
+    eQEP2
+    eQEP2b # Pins only available when video is disabled
 '''
 
 # Instantiate the class to access channel eQEP2, and only initialize
 # that channel
-myEncoder = Encoder.RotaryEncoder(Encoder.eQEP2)
+myEncoder = RotaryEncoder(eQEP2)
+
+# Get the current position
+cur_position = myEncoder.position
+
+# Position can also be set as a property
+next_position = 15
+myEncoder.position = 15
+
+# Reset position to 0
+myEncoder.zero()
+
+# Change mode to relative (default is absolute)
+# You can use setAbsolute() to change back to absolute
+# Absolute: the position starts at zero and is incremented or
+#           decremented by the encoder's movement
+# Relative: the position is reset when the unit timer overflows.
+myEncoder.setRelative()
+
+# Read the current mode (0: absolute, 1: relative)
+# Mode can also be set as a property
+mode = myEncoder.mode
+
+# Read the current frequency of update
+# Returned value is in Hz
+# If you want to set the frequency, specify it also in Hz
+freq = myEncoder.frequency
+
+# Disable your eQEP channel
+myEncoder.disable()
+
+# Check if the channel is enabled
+# The 'enabled' property is read-only
+# Use the enable() and disable() methods to
+# safely enable or disable the module
+isEnabled = myEncoder.enabled
+
 ```
 
 If you need to use further channels, read on the prerequisites in the following section.