Optical Smoke Sensing

Not a smoke alarm. CeilSense Pro is not certified to EN 14604 and does not replace a smoke alarm or fire alarm system. Its optical smoke sensing is experimental and provides no life-safety function. Rely on certified smoke alarms for fire safety. Notifications depend on power, networking, firmware and working automations.

Planned behavior. The firmware for CeilSense Pro is not written yet. This page describes how the optical smoke sensing is planned to work, based on an earlier prototype. Names, timing and behavior can still change at release.

CeilSense Pro has an experimental optical aerosol measurement, meant for research, development and calibration. It gives you a reading to look at, and you can use it for extra notifications in Home Assistant. It is uncertified, it is not calibrated against any smoke alarm standard and it provides no life-safety function.

What You Must Know First

It is not a smoke alarm. Never install CeilSense Pro as one and never rely on it as one.
Certified smoke alarms remain required. In the Netherlands, certified smoke alarms are mandatory on every floor of every home. CeilSense Pro does not count toward this obligation in any way. Install certified smoke alarms regardless of this device.
It can miss smoke and it can trigger falsely. The readings may fail to detect real smoke or fire, may trigger falsely and may stop working at any time, for example through a sensor fault, power loss, a firmware defect or a wrong setting.
The siren is off by default. It stays silent until you turn on Smoke Siren Enabled.
We make no promise that it notices smoke. Do not count on this function to detect fire or smoke.
You stay responsible. It is up to you to provide certified smoke alarms where the law requires them.

How It Measures

The sensor is an Analog Devices ADPD188BI. It uses blue and infrared light to measure how particles in its chamber scatter light.

The firmware compares both readings with a baseline that adapts to the normal state of the room. From the rise above that baseline it calculates ADPD188BI Smoke Index, a relative value and not a concentration. A rise may point to smoke, but it does not prove it.

This logic is simple and meant for experiments. The baseline follows slow changes, so a slow rise can stay below the threshold.

Warm-Up

After every start, the measurement first builds its baseline.

The warm-up needs 36 stable windows, which takes at least three minutes.
If either channel drifts by more than 20 percent, the warm-up starts over. This avoids a baseline built on unstable readings.
During the warm-up the measurement is not armed and cannot start an alert. ADPD188BI Smoke Index stays at 0, which says nothing about the air.
ADPD188BI Baseline Ready turns on when the warm-up is done.

Every restart starts the warm-up again. For that reason the firmware is planned not to restart by itself when the network or Home Assistant is unreachable.

Stable Windows

The firmware evaluates the measurement every five seconds. Each evaluation uses the median of 15 samples.

A window with zero, out-of-range or highly scattered samples is invalid and cannot start an alert. ADPD188BI Measurement Stable shows whether the window is valid.
A window is a candidate when ADPD188BI Smoke Index is above the threshold and both the blue and the infrared channel have risen. ADPD188BI Alarm Candidate shows these candidates.
Four consecutive candidates turn on ADPD188BI Smoke Alert.
Three stable clear windows turn it off again.

What Happens During an Alert

When ADPD188BI Smoke Alert turns on, the device is planned to do this:

The LED ring strobes red.
If Smoke Siren Enabled is on, the buzzer repeats a pattern of three beeps and a pause until the alert clears.
Home Assistant receives the new state, if the device is connected.

The ring and the siren run on the device itself and need no WiFi, Ethernet, Home Assistant or cloud connection. That does not make them a safety function.

When ADPD188BI Smoke Alert is off, this experimental measurement has no alert. Home Assistant may show that as clear, but it does not mean the room is free of smoke.

Controls

Entity	What it is planned to do
`Smoke Siren Enabled`	Allows the siren on the buzzer. Off by default, and it keeps your setting after a restart.
`Smoke Alarm Silence`	Mutes an active siren for 10 minutes and then re-arms it automatically. The ring keeps strobing.
`Smoke Test`	Runs a self-test of the sensor.
`Smoke Self Test Result`	Shows `PASS` or `FAIL` from the last `Smoke Test`.
`Remote Smoke Alarm`	Lets Home Assistant start the siren and the strobe of this unit.

Smoke Test

Smoke Test checks the communication with the sensor, its device ID and a fresh optical sample on both channels.

Pass: Smoke Self Test Result shows PASS, the buzzer plays the pattern and the ring strobes red.
Fail: Smoke Self Test Result shows FAIL, the buzzer plays an error tone and the ring turns solid red.

The test also sounds when Smoke Siren Enabled is off. A pass only shows that the sensor responds. It does not show that the device will notice smoke.

Remote Smoke Alarm and Several Units

Remote Smoke Alarm lets Home Assistant sound this unit, for example when another CeilSense Pro has an alert. The switch is never restored after a restart, so a unit cannot come back with the signal still on. The siren only sounds on a unit where Smoke Siren Enabled is on.

Linking units through Home Assistant has clear limits:

It depends on WiFi or Ethernet and on Home Assistant being up. If one of them is down, the other units do nothing.
Only the unit that sees the change acts on its own. All other units depend on the network.
Do not rely on it. Certified interconnected smoke alarms use their own dedicated radio or wired link.

We do not give an example automation for this, because it could suggest a protection that CeilSense Pro does not offer.

Sensor Problems

ADPD188BI Sensor Problem reports setup failures and failed reads, which would otherwise look like no smoke. Treat every reading from this measurement as unreliable while it is on. See Troubleshooting.

Notification Example

An automation can send you a notification as a supplement to your certified smoke alarms. It is not a safety function: the message depends on power, networking, firmware and working automations.

alias: "CeilSense Pro: supplementary notification, not a safety function"
triggers:
  - trigger: state
    entity_id: binary_sensor.ceilsense_pro_adpd188bi_smoke_alert
    to: "on"
actions:
  - action: notify.mobile_app_your_phone
    data:
      title: "CeilSense Pro"
      message: "Supplementary notification: the experimental optical smoke sensing shows a rise. This does not replace your certified smoke alarms."

Note: Entity IDs can differ per installation, because they start with your device name. Check yours on the device page. Replace notify.mobile_app_your_phone with your own notification action.

Keep automations like this to supplementary notifications. Do not build anything on these readings that people would depend on for their safety.