From 4b333a367dd55b48bb909b0cdffd0c37aefc53cf Mon Sep 17 00:00:00 2001
From: Tilman <tliero@gmx.net>
Date: Tue, 17 Nov 2020 12:39:47 +0100
Subject: [PATCH] Doorbell sender with 10 kOhm pulldown

---
 .../klingel_sender_nano_serial.ino            | 38 ++++++++++++-------
 1 file changed, 25 insertions(+), 13 deletions(-)

diff --git a/klingel_sender_nano_serial/klingel_sender_nano_serial.ino b/klingel_sender_nano_serial/klingel_sender_nano_serial.ino
index 4e75517..178a8ad 100644
--- a/klingel_sender_nano_serial/klingel_sender_nano_serial.ino
+++ b/klingel_sender_nano_serial/klingel_sender_nano_serial.ino
@@ -1,37 +1,49 @@
-int ledPin = LED_BUILTIN;
-int buttonPin = 2; // Button connected to D2 and GND
-int flare_threshold = 20;
+/*
+ *  https://www.arduino.cc/en/Tutorial/BuiltInExamples/Button
+ * 
+ *  D2  -------------
+ *          |       |
+ *        Button    |
+ *          |       |
+ *  +5V -----       |
+ *               10kOhm
+ *                  |
+ *  GND -------------
+ */
+
+const int ledPin = LED_BUILTIN;
+const int buttonPin = 2; // Button connected to D2
+const int flare_threshold = 20;
+
 bool active = false;
 
 void setup() {
   pinMode(ledPin, OUTPUT);
-  pinMode(buttonPin, INPUT_PULLUP);
+  pinMode(buttonPin, INPUT);
   Serial.begin(9600);
-  Serial.println("Starting doorbell sensor");
+  Serial.println("Doorbell sensor");
 }
 
 void loop() {
   int val = digitalRead(buttonPin);
-  
-  if (val == LOW) {
+
+  if (val == HIGH) {
     delay(flare_threshold); // catch flares
     val = digitalRead(buttonPin);
     
-    if (val == LOW && active == false) {
+    if (val == HIGH && active == false) {
       Serial.println("RING");
       digitalWrite(ledPin, HIGH);
       active = true;
       delay(250);
     }
-    else if (val == HIGH) {
+    else if (val == LOW) {
       Serial.print("flare (<");
       Serial.print(flare_threshold);
       Serial.println(")");
     }
-  }
-  else {
-    active = false;
+  } else {
     digitalWrite(ledPin, LOW);
+    active = false;
   }
-  
 }