SmartHomeShop Docs

Troubleshooting

Rapidly flashing red status LED on a VLAN without internet

If your CeilSense continues to report measurements but its red status LED flashes rapidly after startup, the firmware update check may be blocked by your firewall or IoT VLAN.

The local CeilSense firmware reads a small version manifest from SmartHomeShop GitHub Pages. This check only determines whether new firmware is available. It does not send sensor readings, Home Assistant data, Wi-Fi passwords or API keys to GitHub.

ESPHome's standard status LED reports errors from every firmware component. A blocked update check can therefore look like a device startup error even while CeilSense itself is working normally.

Confirm the cause

Open the CeilSense logs in ESPHome and look for http_request.update or Failed to fetch manifest. If these messages are not present, investigate power, network and sensor initialization before changing the update settings.

Disable scheduled firmware checks

  1. Open the ESPHome Device Builder app/add-on in Home Assistant. This is different from the ESPHome integration under Settings > Devices & services.
  2. Find CeilSense and select Take control or Adopt.
  3. Save a copy of the generated YAML, including its API encryption key.
  4. Select Edit and add this block at the bottom of the YAML, without extra indentation:
update:
  - id: !extend firmware_update
    update_interval: never
  1. Save the file, select Validate, and then select Install > Wirelessly.

After installation, CeilSense keeps measuring and communicating locally with Home Assistant, but it no longer performs scheduled firmware checks. You can still update it later through ESPHome or the SmartHomeShop web flasher.

ESPHome still downloads the CeilSense packages: configuration from GitHub while compiling. That request is made by the Home Assistant/ESPHome host, not by CeilSense itself.

If validation says that firmware_update does not exist, remove the block again and install a current CeilSense firmware version first. A rapidly flashing LED that remains after this change can indicate another real firmware or hardware error.

This guide covers common issues with the CeilSense and how to resolve them.

mmWave Radar Issues

Constant Detection / 100% Movement Energy When Room is Empty

This usually means the sensor needs to be calibrated for your specific room.

Symptoms:

  • Presence always shows "detected" even with nobody in the room
  • Movement energy shows 100% constantly
  • Still energy shows high values continuously
  • Lights never turn off because presence is always detected

Causes:

  • Sensor not calibrated after installation
  • Radar detecting through walls into adjacent rooms
  • Ceiling fans or moving objects in detection zone
  • HVAC airflow moving curtains or plants
  • Pets in the detection area
  • Background noise not filtered out

Solution:

  1. Run Dynamic Background Correction (most important!)

    • Completely empty the room: no people, no pets
    • Turn off ceiling fans, close windows
    • In Home Assistant, press "Start Dynamic Background Correction"
    • Wait for the process to complete

  2. Reduce Maximum Distance Gate

    • Lower the max gate to match your room size
    • Each gate ≈ 0.75m, so for a 3m room, set max gate to 4-5

  3. Increase thresholds for problem gates

    • Use the HLK Radar Tool app to see energy per gate
    • Increase Move/Still thresholds for gates showing constant high energy

👉 See the Calibration Guide for detailed step-by-step instructions.

No Detection / Presence Never Triggers

Symptoms:

  • Sensor never detects presence
  • Movement energy always shows 0%
  • Lights don't turn on when entering the room

Causes:

  • Thresholds set too high
  • Maximum distance gate set too low
  • Sensor mounted too high or at wrong angle
  • Physical obstruction blocking the sensor

Solution:

  1. Lower the thresholds

    • Decrease Move and Still thresholds in the HLK Radar Tool app
    • Lower values = more sensitive

  2. Increase Maximum Distance Gate

    • Ensure max gate covers your room size

  3. Check mounting

    • Recommended height: 2.5 to 3 meters
    • Ensure sensor lens is not obstructed

  4. Reset the radar and recalibrate

    • Press the LD2412 Factory Reset button, not the general Factory Reset button
    • Run Dynamic Background Correction with empty room

Detecting Through Walls (Adjacent Room Triggers)

Symptoms:

  • Sensor detects presence when someone is in the next room
  • False triggers from hallway or adjacent spaces

Solution:

  1. Reduce Maximum Distance Gate to limit detection range
  2. Increase thresholds for far gates (gate 8-13) in the HLK Radar Tool app to reduce sensitivity at distance
  3. Consider sensor placement: move away from thin walls if possible

Ceiling Fan Causes Constant Detection

Symptoms:

  • Detection works fine until ceiling fan is turned on
  • Constant movement detection when fan is running

Solution:

  1. Run Dynamic Background Correction with fan ON at your typical speed
  2. Increase the move threshold in the HLK Radar Tool app for gates where the fan is detected
  3. Reduce detection range if fan is at the edge of detection zone

Wi-Fi / Connectivity Issues

For detailed network setup and troubleshooting, see the Network Configuration guide.

Not Discovered in Home Assistant

Solution:

  1. Check that CeilSense is connected to your Wi-Fi network
  2. Try adding the ESPHome integration manually by IP address
  3. Ensure Home Assistant and CeilSense are on the same network/VLAN

Cannot Connect to CeilSense Hotspot

Solution:

  1. Look for SSID: ceilsense (password: ceilsense)
  2. If no hotspot appears, the device may already be connected to Wi-Fi
  3. Try power cycling the device (unplug and replug)
  4. If captive portal doesn't open, browse manually to http://192.168.4.1/

Frequent Disconnections

Solution:

  1. Check Wi-Fi signal strength at ceiling level
  2. Consider using Ethernet/PoE for more reliable connection
  3. See Network Configuration for how to switch

Ethernet Issues

For Ethernet-specific issues (device offline after switching, not discovered, etc.), see the Network Configuration Troubleshooting section.

Environmental Sensor Issues (Complete Only)

Temperature Readings Too High

Causes:

  • LED ring generating heat
  • Poor airflow in ceiling cavity
  • Well-insulated ceiling trapping heat

Solution:

  1. Reduce LED brightness or usage
  2. Apply a temperature offset with SCD4x Extra Temperature Offset (°C) in Home Assistant
  3. See Calibration Guide for details

CO₂ Readings Inaccurate

Causes:

  • Sensor not calibrated yet. Automatic self-calibration (ASC) is off by default
  • Sensor was calibrated while the air was not fresh

Solution:

  1. Run manual CO₂ calibration in fresh outdoor air
  2. See Calibration Guide for details
  3. Only turn on ASC if the room regularly gets fresh air

CO₂ Never Drops Below 600 ppm

Cause:

  • The sensor has not been calibrated in fresh air yet

Solution:

  1. Ventilate the room thoroughly (open windows for 20+ minutes)
  2. Run manual calibration

LED Ring Issues

LEDs Not Working

Solution:

  1. The ring is off by default. Control it with CeilSense Status LED or turn on the functions in LED Lighting
  2. Check power supply (LEDs require adequate power)
  3. Check brightness setting is not at 0%

LEDs Affecting Sensor Readings

Cause:

  • LED ring generates heat that affects temperature/humidity/CO₂ sensors

Solution:

  1. Reduce LED brightness during continuous operation
  2. Use cooldown periods between LED effects
  3. Apply calibration offsets to compensate

Firmware Issues

Cannot Flash Firmware

Solution:

  1. Use a USB-C data cable (not charge-only)
  2. Try a different USB port
  3. Close other applications that might use the serial port
  4. Use Chrome or Edge browser for web flasher

Device Not Responding After Flash

Solution:

  1. Wait 30 seconds for device to boot
  2. Power cycle the device
  3. Device may need to be re-adopted in Home Assistant

Still Having Issues?

If you've tried the solutions above and still have problems:

  1. Check the FAQ for additional answers
  2. Visit the Calibration Guide for detailed tuning instructions
  3. Join our Discord community for support
  4. Contact us via our contact page