Published September 16, 2019 © CC BY

Luminosity Sensor for Home Assistant

Make a luminosity sensor with a Wemos D1 mini and interface it with your HA. Prevent your lights to turn on if sufficient luminosity.

IntermediateFull instructions provided1 hour6,893

Things used in this project

Hardware components

Wemos D1 Mini

Wemos Battery Shield

Light Dependent Resistor - LDR

Resistor 10k ohm

Software apps and online services

Arduino IDE

Story

Why the sensor

Every time I arrived home at night, in the garage, I wasn't able to see anything. Having a little baby, was always hard for me or my wife, to get out of the car and take the baby out in the dark. We need to turn the lights on.

So, I started automating my house and one of the things I did was to put a shelly 2.5 connected to the lights switch. Using a motion sensor, everything connected to Home Assistant, the lights turn on every time motion was detected.

But, this was happening either at night or day. To prevent turning the light in the day, I've decided to create a luminosity sensor, interface it with Home Assistant and only turn the light if the luminosity was bellow a certain value.

It had to be small, cheap and easy for anyone to create, thus this project was born.

Building it

To build it, just follow the schematics, choose Option 1 or Option 2 - or come up with one yourself to power the Wemos

Here's one in a breadboard and with a 3D printed case

1 / 2 • Using the Wemos Battery Shield

Deep Sleep

To save battery, the code uses the Wemos deep sleep mode to save battery.

For deep sleep to work, you need to put a blob of solder in the Wemos were it says "sleep".

The solder blob to allow the Wemos to deep sleep

WARNING: After you put the solder blob, uploading sketches to the Wemos becomes much harder. It is possible, but involves having to reset the board a lot of times.

Only do this after uploading the code if you don't want to have to reset the board a lot of times.

Code

The code doesn't have a lot of configurations. Just fill the following parameters to reflect your configurations

MQTT_SERVER
MQTT_USER
MQTT_PASSWORD
MQTT_PORT (if not standard)
MQTT_TOPIC (you can put whatever you want here, but in home assistant configuration must be the same)
*ssid - wifi network name
*password - wifi password
SLEEP_TIME (in seconds): The frequency of updates to HA

Home Assistant

In Home Assistant, we just need to add a new sensor and I'm going to show how you can get the values from the new sensor.

The following lines are to be added to sensor.yaml file (or configuration.yaml if you don't have them separated).

# Sensor luminosity
- platform: mqtt
  name: "Luminosidade_garagem"
  state_topic: "sensor/luminosity"
  qos: 0
  unit_of_measurement: "cd"

Restart Home Assistant after adding the sensor.

And here's an example on how to get the values from the sensor

- condition: numeric_state
  entity_id: 'sensor.Luminosidade_garagem'
  below: 450

And here's the sensor values in Home Assistant entity

The sensor history in Home Assistant

Problems

If you don't see any values, after you power on the sensor, check in Home Assistant Mosquitto broker logs if it's getting there:

1568668671: New connection from 192.168.12.22 on port 1883.
1568668671: New client connected from 192.168.12.22 as LightSensor (p2, c1, k15, u'mosquittouser').

Final notes

You can adjust, in the Arduino code, the frequency in which the sensor sends updates on the luminosity (and consequentially the sleep time) to HA.

What can and will happen is, sometimes the sensor just finished sending an update (let's say 900) and your sensor detects movement and the lights don't turn on because there's enough luminosity. But, the luminosity drops to almost pitch black, but the lights don't turn on because the last update was a value of 900 and the sensor hasn't updated the HA.

You can play with the time to best suit your needs.

TODO

I need to design a better case for the sensor

The sensor in the case

Code

/*
 * This code will put the wemos in sleep every 2.5 minuts
 * Hopping it will save battery
 */

#include <ESP8266WiFi.h>
#include <PubSubClient.h>

//#define DEBUG 1
#define DEBUG 0 

// MQTT stuff
#define MQTT_SERVER "HA IP ADDRESS"
#define MQTT_USER "mosquitto_user"
#define MQTT_PASSWORD "mosquitto_password"
#define MQTT_PORT 1883
#define MQTT_TOPIC "sensor/luminosity"

//since we're sleeping, don't need the update time - we're updating when we woke up
#define SLEEP_TIME 180 //3 minutes in seconds 

int lightSensor = A0;

// WIFI
const char *ssid = "wifi_network";
const char *password = "wifi_password";

// MQTT


WiFiClient espClient;
PubSubClient client (espClient);


int lightValue = 0;


void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  
  //wifi setup
  #if DEBUG
    Serial.println("");
    Serial.println("");
    Serial.print("Connecting to wifi...");
    Serial.println(ssid);
  #endif
  
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print("."); 
  }
  #if DEBUG
    Serial.println ("");
    Serial.print("WiFi connected: ");
    Serial.println (WiFi.localIP());
  #endif
  
  //mqtt
  client.setServer(MQTT_SERVER, MQTT_PORT);

  if (!client.connected()) {
    //loop until connected
    while (!client.connected()) {
      #if DEBUG
        Serial.println("Connecting to MQTT..");
      #endif
      if (client.connect("LightSensor", MQTT_USER, MQTT_PASSWORD)) {
        #if DEBUG
          Serial.println("Connected!");
        #endif
      }
      else {
        Serial.print("Error rc=: ");
        Serial.println (client.state());
        Serial.println (" retry in 5 seconds...");
        delay(5000);
      }
    }
  }
 
  client.loop();
  //read luminosity
  lightValue = analogRead(lightSensor);
  #if DEBUG
    Serial.print("Light value: ");
    Serial.println (lightValue);
  #endif
  client.publish (MQTT_TOPIC, String(lightValue).c_str(), true);
  //if we don't put a delay, we'll go to sleep before publishing to MQTT
  delay(500);
  ESP.deepSleep (SLEEP_TIME * 1000000);

}

void loop() {
  // put your main code here, to run repeatedly:
  
}

# Luz #1 garagem -  ligar
# Apenas se luminosidade inferior a 600
- alias: Luz garagem 1 on
  trigger:
    platform: mqtt
    topic: tele/sonoffBridge/RESULT
  condition:
    condition: and
    conditions:
      - condition: template
        value_template: '{{trigger.payload_json.RfReceived.Data == "EE9D2E" }}'
      - condition: numeric_state
        entity_id: 'sensor.Luminosidade_garagem'
        below: 450
  action:
    service: homeassistant.turn_on
    data:
      entity_id: switch.Luz_Garagem_1

Credits

Bruno Santos

4 projects • 3 followers

Linux and Raspberry PI lover! Systems and Network Administrator, programmer, kind of a Nerd!

Luminosity Sensor for Home Assistant

Things used in this project

Hardware components

Software apps and online services

Story

Why the sensor

Building it

Deep Sleep

Code

Home Assistant

Problems

Final notes

TODO

Schematics

Wiring Schematics

Code

Luminosity_Code

automation.yaml

sensor.yaml

Credits

Bruno Santos

Comments

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Luminosity Sensor for Home Assistant

Luminosity Sensor for Home Assistant

Things used in this project

Hardware components

Software apps and online services

Story

Why the sensor

Building it

Deep Sleep

Code

Home Assistant

Problems

Final notes

TODO

Schematics

Wiring Schematics

Code

Luminosity_Code

automation.yaml

sensor.yaml

Credits

Bruno Santos

Comments

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