The Smoke Detector is nowadays a crucial safety equipment that is mandatory in most EU countries and also in the States.

But even if its not mandatory by law in your country i highly advise you do install a few in your house or shop.

Not only that it gives you piece of mind but in case something catches fire you will have some time to react.

The History of the Smoke Detector

The smoke detector, was invented by Francis Robbins Upton and his colleague Fernando J. Dibble in 1890.

Their innovative creation stemmed from Upton’s interest in ionization and radiation. Upton, an associate of Thomas Edison, used the principles of ionization to develop a detector that could sense smoke particles in the air.

This early smoke detector was an electrostatic device that employed charged plates to detect smoke presence. However, it wasn’t until the mid-20th century that the technology evolved into the ionization and photoelectric smoke detectors widely used today. Ionization detectors utilize a small amount of radioactive material to ionize the air between two electrically charged plates, while photoelectric detectors rely on a light beam disrupted by smoke particles.

The continuous advancements and integration of various technologies have refined smoke detectors into highly efficient, life-saving devices, becoming an essential component in ensuring fire safety and saving countless lives worldwide.

What do you need to flash the Tuya Smoke Detector LSC PD-8912 with Tasmota

• a Windows PC, Chromebook or Linux/Mac machine
• a USB to TTL serial converter
• the template found here

Flashing the Tuya Smoke Detector LSC PD-8912 with Tasmota

First we need to take the device apart and get acces to its motherboard.

The are 4 screws that you need to take out and te board is held in place with some clips.

Also before you remove the board from the case you must disconnect the buzzer from the motherboard.

On the back of the LSC PD-8912 motherboard you find find the TYWE3S and some marked pins.

The pins are located on the left of the TYWE3S chip and 2 rows.

The pins that interest up are:

• LRX
• LTX
• GND
• VCC

Now in order to comunicate with the TYWE3S we need to make the following connections with the USB to Serial board but dont plug the board into the computer yet.

Bu make to connections you can use some standard breadboard cables or a Flashing Jig that you can connect directly to the ESP.

You must set the USB to TTL board to 3.3V

• LRX on the board – TX on the TTL board
• LTX on the board – TX on the TTL board
• GND – GND
• VCC – VCC 3.3V

With the connections made you must put the TYWE3S into flashing mode. To do that what you need to do is the following: connect GND with GPIO0 while you plug the USB to TTL to the computer

Now get ready to flash the devices with your preferred app.

The firmware that were using is tasmota-lite.bin that you can download from here.

Now plug the USB to TTL to the computer while you put the TYWE3S into flashing mode (you need to hold the connection for 5s or so) and quickly press and hold the small black button on the Smoke Detectors board until the red LED starts to flash.

You need to hold the button for 5s or so in order to energize the ESP, you need to repetate the holding of the button as soon as the LED stops flashing.

Its recommended to backup the original firmware before flashing and after the backup is finished (ive used Tasmotizer) then flash the tasmote-lite.bin file. Dont forget to press the button on the motherboard to keep the ESP energized.

And done!

After the flash is successful you still need to have to board powered via the TTL adapter and do the necessity configuration in MQTT.

Press the button on the motherboard again to keep it connected to the WIFI.

First you need to connect the device to the network.

Search for the Tasmota hotspot that it creates then connect to it and configure your WIFI. After it connects to WIFI connect to its new IP address.

Next go to Configuration – Configuration Other and apply this template:

{"NAME":"Nedis WIFIDS10WT","GPIO":[0,107,0,108,0,0,0,0,0,0,0,0,0],"FLAG":0,"BASE":54}

Make sure to check the button „Apply” in order to apply the configuration. Hit save!

The device will reboot and after that we have to apply some options in the Console:

SetOption97 0

TuyaMCU 51,51

Backlog SetOption1 1; SetOption65 1

Rule1
ON TuyaReceived#Data=55AA0005000501040001000F DO publish stat/%topic%/FIRE ON ENDON
ON TuyaReceived#Data=55AA00050005010400010110 DO publish stat/%topic%/FIRE OFF ENDON
ON TuyaReceived#CmndData=0E04000102 DO publish stat/%topic%/BATT OFF ENDON
ON TuyaReceived#CmndData=0E04000100 DO publish stat/%topic%/BATT ON ENDON

Rule1 1

Rule2
ON system#boot do publish homeassistant/binary_sensor/%macaddr%_fire/config {"name":"Fire Alarm","state_topic":"stat/%topic%/FIRE","device_class":"smoke","unique_id":"%macaddr%_fire","device":{"connections":[["mac","%macaddr%"]]}} ENDON
ON system#boot do publish homeassistant/binary_sensor/%macaddr%_battery/config {"name":"Fire Alarm Battery","state_topic":"stat/%topic%/BATT","device_class":"battery","unique_id":"%macaddr%_battery","device":{"connections":[["mac","%macaddr%"]]}} ENDON
ON system#boot do publish homeassistant/sensor/%macaddr%_battery_voltage/config {"name":"Fire Alarm Batt Volt","state_topic":"stat/%topic%/STATUS11","value_template": "{{ value_json.StatusSTS.Vcc | round (2)}}","unit_of_measurement": "V","device_class":"battery","unique_id":"%macaddr%_battery_voltage","device":{"connections":[["mac","%macaddr%"]]}} ENDON

Rule2 1

SetOption66 1

Apply the settings in Console one after the other. Now the configuration is done. Install in Home Assistant the Tasmota addon and after a restart of Home Assistant wake the smoke detector again with a button press and now its should become available there.