diff --git a/main.py b/main.py
index 1c64e19..1003411 100644
--- a/main.py
+++ b/main.py
@@ -1,10 +1,48 @@
 import time
 import network
 import urequests
+from machine import Pin, time_pulse_us
+
+DOOR_OPEN_THRESHOLD = 50 # in cm
+
+echo_pin = Pin(0, Pin.IN)
+trig_pin = Pin(1, Pin.OUT)
+
+def getDistanceCM():
+    trig_pin.value(0)
+    time.sleep_us(2)
+    trig_pin.value(1)
+    time.sleep_us(10)
+    trig_pin.value(0)
+
+    pulse_time = time_pulse_us(echo_pin, 1, 30000)
+    
+    if pulse_time < 0:
+        return -1 
+        
+    distance = pulse_time / 58
+    return distance
 
 def sendDoorStatus(status):
-    requestURL = "http://10.69.70.1/status"
-    r = urequests.post(requestURL, data={"status", status})
+    print("door status: " + str(status))
+    #requestURL = "http://10.69.70.1/status"
+    #r = urequests.post(requestURL, data={"status", status})
+
+def checkDoorDistance():
+    dist = -1
+    timeoutTime = 10
+    while timeoutTime > 0 and dist == -1:
+        dist = getDistanceCM()
+        timeoutTime -= 1
+        time.sleep(1)
+
+    if dist < DOOR_OPEN_THRESHOLD:
+        sendDoorStatus(1) # door open
+    elif dist == -1:
+        sendDoorStatus(-1) # unknown
+    else:
+        sendDoorStatus(0) # door closed
+
 
 def connectToNet():
     ssid = "ITRnet"
@@ -32,6 +70,6 @@ def connectToNet():
 # program
  
 connectToNet()
-sendDoorStatus(False)
-
-
+while True:
+    time.sleep(5)
+    checkDoorDistance()