--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/doord.py	Fri Jan 19 11:54:24 2018 -0600
@@ -0,0 +1,51 @@
+#!/usr/bin/env python3
+
+import time
+import automationhat
+import sys
+
+import queue
+import threading
+
+
+def main():
+    command_queue = queue.LifoQueue()
+    read_thread = threading.Thread(target=read_loop, args=[command_queue])
+    read_thread.start()
+    run_loop(command_queue)
+
+
+def read_loop(command_queue):
+    while True:
+        command_queue.put_nowait(sys.stdin.readline().rstrip('\n'))
+
+
+def run_loop(command_queue):
+    thread_local = threading.local()
+    thread_local.doorbell_on_state = False
+
+    while True:
+        run_command(command_queue)
+        read_doorbell(thread_local)
+
+
+def run_command(command_queue):
+    try:
+        command = command_queue.get(timeout=0.5)
+    except queue.Empty:
+        pass
+    else:
+        automationhat.relay.on() if command == "unlock" else automationhat.relay.off()
+
+
+def read_doorbell(thread_local):
+    analog_value = automationhat.analog.one.read()
+    doorbell_on_state = 6.0 < analog_value and analog_value < 6.3
+
+    if doorbell_on_state != thread_local.doorbell_on_state:
+        thread_local.doorbell_on_state = doorbell_on_state
+        print("doorbell_on") if doorbell_on_state else print("doorbell_off")
+
+
+if __name__ == "__main__":
+    main()