Hacking Arlec's 'Smart' sensor light

Quite some time ago, I purchased one of the Arlec Smart Security Lights from Bunnings. The big draw for me was that these devices have an ESP8266, and run a Tuya firmware, which can be trivially flashed without opening up the unit.

In this case, though, the device was not really that capable. Whilst there is a PIR sensor (and an LDR for tuning if the light should turn on yet or not), the status of the PIR is not exposed at all. Instead, the firmware allows toggling between three states: “ON”, “OFF”, and “SENSOR”.

That’s not actually that useful. For one, it makes using it in conjunction with a physical switch really inconvenient. The behaviour I would prefer is:

  • Light ON/OFF state can be toggled by network request.
  • Light ON/OFF state can be toggled by physical switch. It must not matter which state the switch is in, toggling it must toggle the light.
  • PIR ON turns ON the light.
  • PIR OFF turns OFF the light, but only if it was turned ON by PIR.

As the last point indicates, the only time the PIR turning off should turn the light off is if the light was turned on by the PIR. That is, either physical switch actuation or a network request should turn the light into manual override ON.

There is no manual override OFF.

Most of this was already present in a firmware I wrote for adding a PIR to a light strip. However, the ability to also toggle the state using a physical switch is important to me: not in the least because there is a switch inside the door where I want to mount this, and I’m very likely to accidentally turn it on when I go outside: it’s also a much better solution to a manual override than just having to use HomeKit. I’ll possibly add that feature back into the aforementioned project.

Like all of the other Grid Connect hardware I’ve used so far, it was easy to flash using tuya convert. But I did run into a bunch of problems from that point onwards. The base contains the ESP8266, one of the TYWE2S units, and it’s possible to see without opening up the sensor unit that this has three GPIO pins connected: GPIO4, GPIO5 and GPIO12.

With a custom firmware, it was possible to see that GPIO5 is connected to the green LED near the PIR sensor, but the other two appear to be connected to another IC on the PCB. I thought perhaps this could be accessed using the TuyaMCU protocol, but had no luck.

As it turns out, I’d prefer not to have to use that. There are two more wires, it would be great if I could connect one of them to the relay, and the other to the PIR.

Indeed, with limited rewiring (I did have to cut some tracks and run wires elsewhere), I was able to connect GPIO12 to the point on the PCB that the output from the other IC that triggered the relay, and GPIO4 to the input of the IC that was sensing the PIR output.

I also ran an extra pair of wires from GPIO14 and GND, to use to connect to the physical switch. These will only transmit low voltage.

Unfortunately, I forgot to take photos before putting it all back together and having it mounted on the wall.

Then we just need the firmware:

esphome:
  name: $device_name
  platform: ESP8266
  board: esp01_1m

globals:
  - id: manual_override
    type: bool
    restore_value: no
    initial_value: 'false'
  - id: mqtt_triggered
    type: bool
    restore_value: no
    initial_value: 'false'

sensor:
  - platform: wifi_signal
    name: "WiFi signal sensor"
    update_interval: 60s

binary_sensor:
  - platform: gpio
    pin: GPIO4
    id: pir
    device_class: motion
    filters:
      - delayed_off: 15s
    on_press:
      - light.turn_on: green_led
      - mqtt.publish:
          topic: HomeKit/${device_name}/MotionSensor/MotionDetected
          payload: "1"
      - switch.turn_on: relay
    on_release:
      - light.turn_off: green_led
      - mqtt.publish:
          topic: HomeKit/${device_name}/MotionSensor/MotionDetected
          payload: "0"
      - if:
          condition:
            lambda: 'return id(manual_override);'
          then:
            logger.log: "Manual override prevents auto off."
          else:
            switch.turn_off: relay

  - platform: gpio
    pin:
      number: GPIO14
      mode: INPUT_PULLUP
    name: "Toggle switch"
    filters:
      - delayed_on_off: 100ms
    on_state:
      - switch.toggle: relay
      - globals.set:
          id: manual_override
          value: !lambda "return id(relay).state;"

ota:

logger:

output:
  - platform: esp8266_pwm
    id: gpio5
    pin:
      number: GPIO5
    inverted: False

switch:
  - platform: gpio
    id: relay
    pin:
      number: GPIO12
      # inverted: True
      # mode: INPUT_PULLDOWN_16
    on_turn_on:
      - if:
          condition:
            lambda: 'return id(mqtt_triggered);'
          then:
            logger.log: "No MQTT message sent"
          else:
            mqtt.publish:
              topic: HomeKit/${device_name}/Lightbulb/On
              retain: ON
              payload: "1"
    on_turn_off:
      - if:
          condition:
            lambda: 'return id(mqtt_triggered);'
          then:
            logger.log: "No MQTT message sent"
          else:
            mqtt.publish:
              topic: HomeKit/${device_name}/Lightbulb/On
              retain: ON
              payload: "0"


light:
  - platform: monochromatic
    id: green_led
    output: gpio5
    restore_mode: ALWAYS_OFF
    default_transition_length: 100ms

mqtt:
  broker: "mqtt.lan"
  discovery: false
  topic_prefix: esphome/${device_name}
  on_message:
    - topic: HomeKit/${device_name}/Lightbulb/On
      payload: "1"
      then:
        - globals.set:
            id: mqtt_triggered
            value: 'true'
        - switch.turn_on: relay
        - globals.set:
            id: mqtt_triggered
            value: 'false'
        - globals.set:
            id: manual_override
            value: !lambda "return !id(pir).state;"
    - topic:  HomeKit/${device_name}/Lightbulb/On
      payload: "0"
      then:
        - globals.set:
            id: mqtt_triggered
            value: 'true'
        - switch.turn_off: relay
        - globals.set:
            id: manual_override
            value: 'false'
        - globals.set:
            id: mqtt_triggered
            value: 'false'

I’ve also implemented a filter on sending the state to MQTT: basically, we don’t want to send a message to MQTT if we received the same message. There is a race condition that can occur where this results in fast toggling of the relay as each toggle sends a message, but then receives a message with the alternate state. I’ve had this on my Sonoff Mini firmware too.

Adding a PIR sensor to an Arlec Smart LED Strip

I built a shed on Australia Day.

Actually, I built two of them over the Australia Day Long Weekend. I bought them from easyshed.com.au, and they were pretty nifty. Specifically, I bought a couple of the off the wall sheds, to attach them to the wall of my garage. There’s already a concrete path there that I was able to use as the floor.

One of the sheds is longer than the others, and is used for storage of tools. Mostly I need to get stuff during the day, but sometimes at night I may need to access something from in there. So, I bought a 2m Grid Connect LED Strip Light. It’s colour changing, but I’m not really that fussed about the colours: this one has a Warm White LED too, so that’s better than trying to twiddle the colours to get the right temperature.

Being Grid Connect, it’s really Tuya, which means it’s flashable. So I did. I’ve got a nice esphome firmware on there, which hooks it up to HomeKit via my MQTT bridge.

I wasn’t really able to get the colour parts working correctly, so I just disabled those pins, and use the light in monochromatic mode.

However, being the tinkerer I am, I opened it up to have a look inside. It’s got one of the standard Tuya mini-boards, in fact a TYWE3S.

This exposes a bunch of pins, most of which were in use:

  • GPIO 0: (Used during boot)
  • GPIO 2: UART0 (TX)
  • GPIO 4: Red LED channel
  • GPIO 5: Warm White LED channel
  • GPIO 12: Green LED channel
  • GPIO 13: unused
  • GPIO 14: Blue LED channel
  • GPIO 15: (Used during boot)
  • GPIO 16: unused

Because the LED strip runs at 12V, I was able to use this to power a PIR sensor, which I then hooked up to GPIO 13. I also tried to connect a DS18B20 temperature sensor to GPIO 16, but was not able to get it to be recognised. From the page linked above, perhaps I needed a pull-up resistor, however, I didn’t really need a temperature sensor.

Having a PIR sensor on the LED strip is worthwhile, however. Otherwise, you’d need to manually turn the lights on when going into the shed.

Having a sensor light is fantastic, but at times you might want the light to stay on, even when it does not detect motion. To achieve this, I have a global variable manual_override, that is set when the light is turned on “manually” (using HomeKit, as there is no physical switch). When this variable is set, the light will not turn off when motion is no longer detected.

I also found it was simpler to have the motion detector (binary_sensor in esphome) have a “delayed off” filter for the period I wanted the light to stay on for, rather than try to manage that in conjunction with the manual override.

The full YAML follows:

esphome:
  name: $device_name
  platform: ESP8266
  board: esp01_1m
  on_loop:
    then:
      - if:
          condition:
            not:
              mqtt.connected:
          then:
            - globals.set:
                id: has_connected_to_mqtt
                value: 'false'

globals:
  - id: has_connected_to_mqtt
    type: bool
    restore_value: no
    initial_value: 'false'
  - id: manual_override
    type: bool
    restore_value: no
    initial_value: 'false'

light:
  - platform: monochromatic
    name: "White"
    id: white
    output: white_channel
    restore_mode: ALWAYS_OFF
    default_transition_length: 0.25s

output:
  - platform: esp8266_pwm
    pin:
      number: GPIO5
    id: white_channel
    inverted: False

sensor:
  - platform: wifi_signal
    name: "WiFi signal sensor"
    update_interval: 5min

binary_sensor:
  - platform: gpio
    pin: GPIO13
    name: "PIR Sensor"
    device_class: motion
    id: pir
    filters:
      - delayed_off: 15s
    on_press:
      then:
        - mqtt.publish:
            topic: HomeKit/${device_name}/MotionSensor/MotionDetected
            payload: "1"
        - if:
            condition:
              light.is_off: white
            then:
              - light.turn_on: white
              - mqtt.publish:
                  topic: HomeKit/${device_name}/Lightbulb/On
                  payload: "1"
    on_release:
      - mqtt.publish:
          topic: HomeKit/${device_name}/MotionSensor/MotionDetected
          payload: "0"
      - if:
          condition:
            lambda: 'return id(manual_override);'
          then:
            - logger.log: "Manual override prevents auto off."
          else:
            - logger.log: "Turning off after motion delay."
            - if:
                condition:
                  - light.is_on: white
                then:
                  - light.turn_off: white
                  - mqtt.publish:
                      topic: HomeKit/${device_name}/Lightbulb/On
                      payload: "0"

ota:

logger:

mqtt:
  broker: "mqtt.lan"
  discovery: false
  topic_prefix: esphome/${device_name}
  on_message:
    - topic: HomeKit/${device_name}/Lightbulb/Brightness
      then:
        - logger.log: "Brightness message"
        - globals.set:
            id: manual_override
            value: 'true'
        - light.turn_on:
            id: white
            brightness: !lambda "return atof(x.c_str()) / 100;"
        - globals.set:
            id: has_connected_to_mqtt
            value: 'true'

    - topic: HomeKit/${device_name}/Lightbulb/On
      payload: "1"
      then:
        - logger.log: "Turn on message"
        - if:
            condition:
              and:
                - binary_sensor.is_off: pir
                - lambda: "return id(has_connected_to_mqtt);"
            then:
              - globals.set:
                  id: manual_override
                  value: 'true'
              - logger.log: "Manual override enabled"
            else:
              - globals.set:
                  id: manual_override
                  value: 'false'
              - logger.log: "Manual override disabled"
        - light.turn_on:
            id: white
        - globals.set:
            id: has_connected_to_mqtt
            value: 'true'
    - topic: HomeKit/${device_name}/Lightbulb/On
      payload: "0"
      then:
        - logger.log: "Turn off message"
        - if:
            condition:
              lambda: 'return id(has_connected_to_mqtt);'
            then:
              - light.turn_off:
                  id: white
              - globals.set:
                  id: manual_override
                  value: 'false'
              - logger.log: "Manual override disabled"
        - globals.set:
            id: has_connected_to_mqtt
            value: 'true'

  birth_message:
    topic: HomeKit/${device_name}/Lightbulb/On
    payload: "1"
  will_message:
    topic: HomeKit/${device_name}/Lightbulb/On
    payload: "0"

There’s also some logic in there to prevent the light turning off and then back on when it first connects to the MQTT broker and is already turned on.

Arlec Powerboard esphome

I bought one of the Grid Connect powerboards from Bunnings last week, and flashed it with a custom firmware.

The model I bought was the PB89HA, which is the one with 5 sockets (one of which is not switchable).

The button is on GPIO3, and the LED is an inverted GPIO1.

The four relays are on GPIO5, GPIO4, GPIO13 and GPIO12, starting with the one closest to the button.

Since there is only one button, and four switchable outlets, I had to come up with a mechanism for controlling all of them. I ended up (after playing around with single-through-quadruple click) with a single click for toggling the first relay (nearest the button). Then, a medium (between 1 and 2 second) press turns all relays off, and a long (greater than 2 second) press turns them all on.

This is not really ideal, as there is no way to toggle just relay 2-4 without using some sort of external control - which goes against my ethos with respect to smart home.

Having said that, I’m not actually sure how I’m going to use this board…I don’t really have a bunch of things that are potentially close together that need individual control. I guess I could have it turn off everything in the entertainment unit except the PVR - that might be a way to save power overnight. I’d want the button more accessible than the powerboard that currently controls them though.

Anyway, the base YAML file follows - be aware that this does not include wifi, and would need to be included in an actual config file (with a device name defined).

esphome:
  name: $device_name
  platform: ESP8266
  board: esp01_1m
  on_boot:
    - light.turn_on:
        id: led
        brightness: 20%

binary_sensor:
  - platform: status
    name: "Status"

  - platform: gpio
    pin:
      number: GPIO3
      inverted: true
      mode: INPUT_PULLUP
    name: button
    on_multi_click:
      - timing:
        - ON for at least 1s
        - OFF for at least 0.2s
        then:
          - switch.turn_off: relay_0
          - switch.turn_off: relay_1
          - switch.turn_off: relay_2
          - switch.turn_off: relay_3

      - timing:
        - ON for at least 2s
        - OFF for at least 0.2s
        then:
          - switch.turn_on: relay_0
          - switch.turn_on: relay_1
          - switch.turn_on: relay_2
          - switch.turn_on: relay_3

      - timing:
        - ON for at most 0.5s
        - OFF for at least 0.2s
        then:
          - switch.toggle: relay_0

switch:
  - platform: gpio
    id: relay_0
    pin: GPIO5
    on_turn_on:
      - mqtt.publish:
          topic: HomeKit/${device_name}/Outlet/0/On
          retain: ON
          payload: 1
    on_turn_off:
      - mqtt.publish:
         topic: HomeKit/${device_name}/Outlet/0/On
         retain: ON
         payload: 0

  - platform: gpio
    id: relay_1
    pin: GPIO4
    on_turn_on:
      - mqtt.publish:
          topic: HomeKit/${device_name}/Outlet/1/On
          retain: ON
          payload: 1
    on_turn_off:
      - mqtt.publish:
         topic: HomeKit/${device_name}/Outlet/1/On
         retain: ON
         payload: 0

  - platform: gpio
    id: relay_2
    pin: GPIO13
    on_turn_on:
      - mqtt.publish:
          topic: HomeKit/${device_name}/Outlet/2/On
          retain: ON
          payload: 1
    on_turn_off:
      - mqtt.publish:
         topic: HomeKit/${device_name}/Outlet/2/On
         retain: ON
         payload: 0

  - platform: gpio
    id: relay_3
    pin: GPIO12
    on_turn_on:
      - mqtt.publish:
          topic: HomeKit/${device_name}/Outlet/3/On
          retain: ON
          payload: 1
    on_turn_off:
      - mqtt.publish:
         topic: HomeKit/${device_name}/Outlet/3/On
         retain: ON
         payload: 0

light:
  - platform: monochromatic
    output: led1
    id: led
    restore_mode: ALWAYS_ON

output:
  - platform: esp8266_pwm
    pin:
      number: GPIO1
    id: led1
    inverted: True

sensor:
  - platform: wifi_signal
    name: "WiFi signal sensor"
    update_interval: 5min

ota:

logger:

mqtt:
  broker: "mqtt.lan"
  discovery: false
  topic_prefix: esphome/${device_name}
  on_message:
    - topic: HomeKit/${device_name}/Outlet/0/On
      payload: "1"
      then:
        - switch.turn_on:
            id: relay_0
    - topic: HomeKit/${device_name}/Outlet/0/On
      payload: "0"
      then:
        - switch.turn_off:
            id: relay_0

    - topic: HomeKit/${device_name}/Outlet/1/On
      payload: "1"
      then:
        - switch.turn_on:
            id: relay_1
    - topic: HomeKit/${device_name}/Outlet/1/On
      payload: "0"
      then:
        - switch.turn_off:
            id: relay_1

    - topic: HomeKit/${device_name}/Outlet/2/On
      payload: "1"
      then:
        - switch.turn_on:
            id: relay_2
    - topic: HomeKit/${device_name}/Outlet/2/On
      payload: "0"
      then:
        - switch.turn_off:
            id: relay_2

    - topic: HomeKit/${device_name}/Outlet/3/On
      payload: "1"
      then:
        - switch.turn_on:
            id: relay_3
    - topic: HomeKit/${device_name}/Outlet/3/On
      payload: "0"
      then:
        - switch.turn_off:
            id: relay_3