Last Updated or created 2025-10-21

December is coming, time for candles.

The plan is to make a flame sensor, with in combination with my presence sensor will alert me when we leave the room and candles are on, give us a notification.

Above is the schematic. A Wemos mini (left over from another project), an analog multiplexer and a cheap 5 times flame detector.
There is a potentiometer on this board to change the sensitivity.

Search “Infrared Ir Flame Sensor Detector Fire Detection Module 5 Channel” on Aliexpress. These are 1 euro.

Presence sensor:

HLK-LD2410B with a Wemos Mini D1 (v4) connected to Home Assistant using ESPHome

Here is some Arduino code.

#define MUX_A D5
#define MUX_B D6
#define MUX_C D7
#define ENABLE D1

#define ANALOG_INPUT A0


void setup() {
    Serial.begin(9600);

  //Define output pins for Mux
  pinMode(MUX_A, OUTPUT);
  pinMode(MUX_B, OUTPUT);     
  pinMode(MUX_C, OUTPUT);     
  pinMode(ENABLE, OUTPUT);     
  digitalWrite(ENABLE, LOW); // No need to switch, can be permanenty low
  
}

void changeMux(int c, int b, int a) {
  digitalWrite(MUX_A, a);
  digitalWrite(MUX_B, b);
  digitalWrite(MUX_C, c);
}

void loop() {
  float value;
  
  
  changeMux(LOW, LOW, HIGH);
  value = analogRead(ANALOG_INPUT); //Value of the sensor connected Option 1 pin of Mux
  Serial.print("Variable_1:");
  Serial.print(value);
  Serial.print(",");

  changeMux(LOW, HIGH, LOW);
  value = analogRead(ANALOG_INPUT); //Value of the sensor connected Option 2 pin of Mux
  Serial.print("Variable_2:");
  Serial.print(value);
  Serial.print(",");

  changeMux(LOW, HIGH, HIGH);
  value = analogRead(ANALOG_INPUT); //Value of the sensor connected Option 3 pin of Mux
  Serial.print("Variable_3:");
  Serial.print(value);
  Serial.print(",");

  changeMux(HIGH, LOW, LOW);
  value = analogRead(ANALOG_INPUT); //Value of the sensor connected Option 4 pin of Mux
  Serial.print("Variable_4:");
  Serial.print(value);
  Serial.print(",");

  changeMux(HIGH, LOW, HIGH);
  value = analogRead(ANALOG_INPUT); //Value of the sensor connected Option 5 pin of Mux
  Serial.print("Variable_5:");
  Serial.println(value);
}

ESPHOME Code

esphome:
  name: flamedetector
  friendly_name: FlameDetector
  on_boot:
    priority: 600
    then:
      - switch.turn_off: enable 

esp8266:
  board: d1_mini

# Enable logging
logger:

# Enable Home Assistant API
api:
  encryption:
    key: "BMHbLdN6Rxxxxxxxxxxxxxxxxxxxxv0LE="

ota:
  - platform: esphome
    password: "780fe0xxxxxxxxxxxxxxxxxxxxx7859"

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "Flamedetector Fallback Hotspot"
    password: "cm1xxxxxxxxxxxxNX"

captive_portal:

switch:
  - platform: gpio
    id: enable
    pin:
      number: D1

cd74hc4067:
  - id: cd74hc4067_1
    pin_s0: D5
    pin_s1: D6
    pin_s2: D7
    pin_s3: D2

globals:
  - id: last_flame_state
    type: bool
    restore_value: no
    initial_value: 'false'
  - id: trigger_on
    type: bool
    restore_value: no
    initial_value: 'false'

sensor:
  - platform: adc
    id: adc_sensor
    pin: A0
    name: flameanalog
    update_interval: 10s
  - platform: cd74hc4067
    id: flame_1_1
    name: flame_1_1
    number: 1
    sensor: adc_sensor
    update_interval: 10s
  - platform: cd74hc4067
    id: flame_1_2
    name: flame_1_2
    number: 2
    sensor: adc_sensor
    update_interval: 10s
  - platform: cd74hc4067
    id: flame_1_3
    name: flame_1_3
    number: 3
    sensor: adc_sensor
    update_interval: 10s
  - platform: cd74hc4067
    id: flame_1_4
    name: flame_1_4
    number: 4
    sensor: adc_sensor
    update_interval: 10s
  - platform: cd74hc4067
    id: flame_1_5
    name: flame_1_5
    number: 5
    sensor: adc_sensor
    update_interval: 10s


interval:
  - interval: 10s
    then:
      - lambda: |-
          const float threshold = 0.01;
          bool any_above =
            id(flame_1_1).state > threshold ||
            id(flame_1_2).state > threshold ||
            id(flame_1_3).state > threshold ||
            id(flame_1_4).state > threshold ||
            id(flame_1_5).state > threshold;

          // Store the result
          if (any_above != id(last_flame_state)) {
            id(last_flame_state) = any_above;
            if (any_above) {
              ESP_LOGI("flame_check", "Flame detected (turning ON)");
              id(trigger_on) = true;
            } else {
              ESP_LOGI("flame_check", "No flame detected (turning OFF)");
              id(trigger_on) = false;
            }
          }

  - interval: 1s
    then:
      - if:
          condition:
            lambda: 'return id(trigger_on);'
          then:
            - homeassistant.service:
                service: homeassistant.turn_on
                data:
                  entity_id: input_boolean.testtoggle
          else:
            - homeassistant.service:
                service: homeassistant.turn_off
                data:
                  entity_id: input_boolean.testtoggle