Requirements

  • Arduino nano
  • ACS712 current sensor
  • ESP8266 wifi module
  • Backend (PHP server in our case)
  • Webserver to serve static html files
  • Sequel database tot store the records when someone rang the bell

Hello reader, this post is about a smart doorbell.

The concept was to create a smart doorbell. Wich wasn’t expensive and hard to install.

What was achieved was something smart and easy to install on your existing electric installation wich sends you a message on your smartphone when someone rings your doorbell.

To push notifications to the smartphone of the user the firebase cloud messaging service was used.

Arduino Code to measure current







/*
Measuring AC Current Using ACS712
*/
const int sensorIn = A0;
int mVperAmp = 66;
double Voltage = 0;
double VRMS = 0;
double AmpsRMS = 0;
int count = 0;

void setup()
{
    Serial.begin(57600);
}
void loop()
{
    Voltage = getVPP();
    VRMS = (Voltage / 2.0) * 0.707;
    AmpsRMS = (VRMS * 1000) / mVperAmp;
}
float getVPP()
{
    float result;
    int readValue;             //value read from the sensor
    int maxValue = 0;          // store max value here
    int minValue = 1024;          // store min value here
    uint32_t start_time = millis();
    while ((millis() - start_time) < 1000) //sample for 1 Sec
    {
        readValue = analogRead(sensorIn);
        // see if you have a new maxValue
        if (readValue > maxValue)
        {
            /*record the maximum sensor value*/
            maxValue = readValue;
        }
        if (readValue < minValue)
        {
            /*record the maximum sensor value*/
            minValue = readValue;
        }
    }
    // Subtract min from max
    if (count != 0)
    {
      count--;
    }
    result = ((maxValue - minValue) * 5.0) / 1024.0;
    //Serial.println(result);
    if (result > 0.050 && count == 0)
    {
      count = 5;
      Serial.print("P");
      //delay(5000);
    }
    return result;
}