added examples

examples/onewire_demo.py

@@ -0,0 +1,31 @@
+import board
+from adafruit_onewire.bus import OneWireBus
+
+# Create the 1-Wire Bus
+# Use whatever pin you've connected to on your board
+ow_bus = OneWireBus(board.D2)
+
+# Reset and check for presence pulse.
+# This is basically - "is there anything out there?"
+print("Resetting bus...", end='')
+if ow_bus.reset():
+    print("OK.")
+else:
+    raise RuntimeError("Nothing found on bus.")
+
+# Run a scan to get all of the device ROM values
+print("Scanning for devices...", end='')
+devices = ow_bus.scan()
+print("OK.")
+print("Found {} device(s).".format(len(devices)))
+
+# For each device found, print out some info
+for i, d in enumerate(devices):
+    print("Device {:>3}".format(i))
+    print("\tSerial Number = ", end='')
+    for byte in d.serial_number:
+        print("0x{:02x} ".format(byte), end='')
+    print("\n\tFamily = 0x{:02x}".format(d.family_code))
+
+# Usage beyond this is device specific. See a CircuitPython library for a 1-Wire
+# device for examples and how OneWireDevice is used.