+# Sample code for both the RotaryEncoder class and the Switch class.
+# The common pin for the encoder should be wired to ground.
+# The sw_pin should be shorted to ground by the switch.
+
+# Output looks like this:
+#
+# A B STATE SEQ DELTA SWITCH
+# 1 1 3 2 1 0
+# 0 1 2 3 1 0
+# 0 0 0 0 1 0
+# 1 0 1 1 1 0
+# 1 1 3 2 1 0
+# 0 1 2 3 1 0
+
+import gaugette.rotary_encoder
+import gaugette.switch
+import math
+
+A_PIN = 5
+B_PIN = 4
+SW_PIN = 2
+
+encoder = gaugette.rotary_encoder.RotaryEncoder(A_PIN, B_PIN)
+switch = gaugette.switch.Switch(SW_PIN)
+
+last_state = None
+last_switch_state = None
+last_delta = 0
+last_sequence = encoder.rotation_sequence()
+last_heading = 0
+
+# NOTE: the library includes individual calls to get
+# the rotation_state, rotation_sequence and delta values.
+# However this demo only reads the rotation_state and locally
+# derives the rotation_sequence and delta. This ensures that
+# the derived values are based on the same two input bits A and B.
+# If we used the library calls, there is a very real chance that
+# the inputs would change while we were sampling, giving us
+# inconsistent values in the output table.
+
+while True:
+
+ state = encoder.rotation_state()
+ switch_state = switch.get_state()
+
+ if (state != last_state or switch_state != last_switch_state):
+ last_switch_state = switch_state
+ last_state = state
+
+ # print a heading every 20 lines
+ if last_heading % 20 == 0:
+ print "A B STATE SEQ DELTA SWITCH"
+ last_heading += 1
+
+ # extract individual signal bits for A and B
+ a_state = state & 0x01
+ b_state = (state & 0x02) >> 1
+
+ # compute sequence number:
+ # This is the same as the value returned by encoder.rotation_sequence()
+ sequence = (a_state ^ b_state) | b_state << 1
+
+ # compute delta:
+ # This is the same as the value returned by encoder.get_delta()
+ delta = (sequence - last_sequence) % 4
+ if delta == 3:
+ delta = -1
+ elif delta==2:
+ # this is an attempt to make sense out of a missed step:
+ # assume that we have moved two steps in the same direction
+ # that we were previously moving.
+ delta = int(math.copysign(delta, last_delta))
+ last_delta = delta
+ last_sequence = sequence
+
+ print '%1d %1d %3d %4d %4d %4d' % (a_state, b_state, state, sequence, delta, switch_state)