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+
+from machine import Pin, ADC, Timer
+import network
+import time
+import ujson
+from uhashlib import sha256
+import binascii
+import math
+import urequests
+
+
+######################################################## CONFIG ########################################################
+# Wifi settings:
+# WIFI_ESSID = 'Your wifi ESSID (name)'
+# WIFI_PSK = 'Your wifi key'
+#
+# Notification settings:
+# NOTIFICATION_URL = 'https://automation.jaseg.de/notify/klingel'
+# NOTIFICATION_SECRET = b'Your notification proxy secret for this endpoint'
+#
+# NOTIFICATION_COOLDOWN = 60 # how long to wait after sending a notification before sending the next, in seconds
+#
+# Detection settings
+# MEAN_LEN = 8 # Window length for DC offset determination in seconds (1024ms to be exact)
+# RMS_THRESHOLD = 1000  # Threshold for rms detection threshold over 1s window in ADC counts
+######################################################### END ##########################################################
+
+
+def wifi_connect():
+    iface = network.WLAN(network.STA_IF)
+    if not iface.isconnected():
+        print('Connecting to wifi... ')
+        iface.active(True)
+        iface.connect(WIFI_ESSID, WIFI_PSK)
+        for i in range(20):
+            if iface.isconnected():
+                print('Wifi connected. IP config: ', iface.ifconfig())
+                break
+            time.sleep(0.5)
+        else:
+            print("Couldn't connect to wifi.")
+
+
+buf = [0] * 1024
+capture = None
+mean = 0
+rms = 0
+sample_tim = Timer(-1)
+
+def start_sampling():
+    global sample_tim
+    buf_pos = 0
+    buf_sum = 0
+    mean_acc = []
+
+    adc = ADC(Pin(34))
+    adc.atten(ADC.ATTN_11DB)
+
+    def sample_cb(tim):
+        global buf, mean, rms, capture
+        nonlocal adc, buf_pos, buf_sum, mean_acc
+
+        val = adc.read()
+        buf[buf_pos] = val
+        buf_sum += val
+
+        buf_pos += 1
+        if buf_pos == len(buf):
+            buf_pos = 0
+            mean_acc = [buf_sum/len(buf)] + mean_acc[:MEAN_LEN-1]
+            mean = sum(mean_acc)/len(mean_acc)
+            buf_sum = 0
+
+            rms = math.sqrt( sum( (x-mean)**2 for x in buf )/len(buf) )
+            capture = list(buf) # Make a copy
+
+    sample_tim.init(period=1, mode=Timer.PERIODIC, callback=sample_cb) # period in ms
+
+def uhmac(key, data):
+    blocksize = 64
+    key += bytes(64 - len(key))
+    tx = lambda s, x: bytes( b ^ x for b in s )
+    outer = sha256(tx(key, 0x5C))
+    inner = sha256(tx(key, 0x36))
+    inner.update(data)
+    outer.update(inner.digest())
+    return outer.digest()
+
+def usign(secret, payload=None, seq=None):
+    payload = {'time': int(time.time()), 'd': payload}
+    if seq is not None:
+        payload['seq'] = seq
+
+    payload = ujson.dumps(payload).encode()
+    auth = binascii.hexlify(uhmac(secret, payload))
+
+    return ujson.dumps({'payload': payload, 'auth': auth})
+
+def notify(**kwargs):
+    data = usign(NOTIFICATION_SECRET, kwargs)
+    print(time.time(), 'Notifying', NOTIFICATION_URL)
+    urequests.post(NOTIFICATION_URL, data=data, headers={'Content-Type': 'application/json'})
+
+def klingel_notify(rms, capture):
+    notify(rms=rms, capture=capture)
+
+def loop():
+    global rms, capture
+    while True:
+        if rms > RMS_THRESHOLD:
+            wifi_connect()
+            old_capture = capture
+            rms = 0
+            while rms == 0:
+                time.sleep(0.1)
+            rms = 0
+            klingel_notify(rms, [old_capture, capture])
+            time.sleep(NOTIFICATION_COOLDOWN)
+
+        time.sleep(0.1)
+
+wifi_connect()
+start_sampling()
+loop()
+