Blog entries tagged with "air conditioning"

How to reflash a Sensibo Sky with ESPHome

Wednesday, February 28th, 2024 at 08:24pm

A few days ago I mentioned how I had reflashed two Sensibo Sky devices with ESPHome as I prefer that arrangement for controlling my AC units. As there were some gaps in the instructions I found on reddit I decided to fully document my steps here. This may not be the best or only method, but it is what I did.

The reddit post that I started from:

Once I picked up the devices my first challenge was actually opening them up. The reddit post didn’t have any information, I couldn’t see any obvious way and a quick search didn’t turn up anything. I briefly considered just trying to use the exposed pins, but I didn’t know what type of connector and didn’t want to wait, so I turned to my iFixit toolkit, using a couple of the plastic picks to wedge open the white casing from the USB port side.

It turns out this was unnecessary and the case is very easy to open.

The translucent part of the case has a hook that clips into the white part, so if you push down on the Sensibo logo you can slide the white part down slightly and it will then lift off. The translucent part can then be unclipped.

This is the diagram from the reddit post:

This is the pinout of the style of USB to TTL UART I used:

Per the instructions I connected:

  • UART GND to Sensibo GND
  • UART TX to Sensibo RX
  • UART RX to Sensibo TX
  • UART GND to Sensibo pins 0 and 15 (though apparently only 0 is required)

I then powered up the device using the USB port, previously the LED would flash when turned on, now it was on solid.

To confirm that I had a connection I used esptool:

$ esptool flash_id v2.8
Found 1 serial ports
Serial port /dev/ttyUSB0
Detecting chip type... ESP8266
Chip is ESP8266EX
Features: WiFi
Crystal is 26MHz
MAC: c8:c9:a3:a5:d7:16
Enabling default SPI flash mode...
Manufacturer: eb
Device: 6015
Detected flash size: 2MB
Hard resetting via RTS pin...

Satisfied I was able to connect I now went into the ESPHome Dashboard and created a new device, this didn’t have any sensors yet, just enough configuration to connect to my wifi (with a static IP because I find that easier than hoping mDNS will work).

As I was doing this from my main desktop and not the machine the TTL UART was connected to I opted for the Manual Download of the firmware. After doing its thing the dashboard gave me an image file to flash.

As I had used esptool to check the connection, I used it again but now to flash the new image. I didn’t keep a copy of the output but the command was:

$ esptool write_flash 0x0 bedroom_ac.bin

The flashing said that it had completed successfully so I disconnected all the wires from the Sensibo and then powered it up from just the USB connector. I breathed a sign of relief when the ESPHome Dashboard showed the device was ONLINE and I could look at its logs.

On the reddit post are two main ESPHome configs, one from the original author and then another linked in a comment. I used a mix of both of those to end up with my current configuration:

  name: "bedroom-ac"
  friendly_name: Bedroom AC

  board: esp_wroom_02

# Enable logging

# Enable Home Assistant API
    key: "...."


  ssid: !secret wifi_ssid
  password: !secret wifi_password


# see for more info

# sensibo i2c pins
  sda: 02
  scl: 14
  scan: true
  id: bus_a

  id: ir_tx
  pin: 15
  carrier_duty_percent: 50%

  id: ir_rx
   number: 4
   inverted: true
    input: true
    pullup: true

  - platform: hdc1080
      id: dht_temp
      name: Temperature
      - offset: -2.0  # hdc1080 is reading about 2C above ambient so reduce by this offset
      id: dht_humidity
      name: Humidity
    update_interval: 60s
  - platform: wifi_signal
    name: "WiFi Signal"
    id: wifi_dbm
    update_interval: 60s

  - platform: uptime
    name: "Uptime"
    id: device_uptime
    update_interval: 10s

  - platform: gpio
    id: button
    name: Button
      number: 13
      mode: INPUT_PULLUP
      inverted: true

  - id: light_output
    platform: esp8266_pwm
    frequency: 1000 Hz
    pin: 12

  - platform: status_led
    name: LED
    id: led
    output: light_output

  - platform: fujitsu_general
    id: controller
    name: Controller
    receiver_id: ir_rx
    transmitter_id: ir_tx
    sensor: dht_temp
    supports_cool: true
    supports_heat: true
      - lambda: |-
          if (x.mode != CLIMATE_MODE_OFF) {
            auto call = id(led).turn_on();
          } else {
            auto call = id(led).turn_off();

One big difference was that I used friendlyname and that I configured the LED to be on when the climate platform is also on and also be the statusled. The button currently has no action (I need to drill out the case and extend the physical button so it can be used) and I also like having uptime and wifi diagnostics.

With one device converted for use in my bedroom, I then repeated the process for the one in my study.

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Removing the cloud from a Sensibo Sky

Sunday, February 25th, 2024 at 10:21pm

In addition to thinking about a housing for my dishwasher panel I have been looking into a housing for my AC controllers which currently look like:

(yes I know I should have cleaned off the dust before taking the photo, but that was a quick photo taken for a talk at work)

What could the housing be? Do I base it around another wall plate? Do I get a wall mounted project box? Do I buy my first 3d printer?

After my experience with the dishwasher panel I also realised that as this is based on ESPHome, so I could add an indicator LED (red for heating, blue for cooling?) and a button (to quickly switch between a standard preset such as 24°C cooling and turning it off). These would also need to be incorporated into the housing.

In my looking around I found that the housing I wanted does exist, in the form of the Sensibo Sky. While there is Home Assistant integration I prefer a non-cloud solution and I already had that up and running.

I don’t know exactly how I came across it but I found a reddit thread showing how the Sensibo Sky is based on an ESP and had instructions on how to flash ESPHome onto it. This was an intriguing idea, but I wasn’t going to buy two Sensibo Sky units just to reflash them.

But there is eBay and Gumtree

(yes, it is always appropriate to spend 20 minutes watching Randy describe buying a bookshelf on Gumtree, 46:25 into Randy Writes a Novel)

eBay was no help, but on Gumtree I found something. While I was looking for used or broken units, what I found was someone not that far away selling two unused units for less than the price of a single unit. Sold! I picked them up the next day and thanks to the reddit instructions (I will make a separate post with my full steps) I was able to flash them with ESPHome.

A bit of reconfiguring within Home Assistant and these are now my AC controllers. I even have them mounted to the wall so they don’t take up desk or bedside table space.

While the built in LED is only blue I did configure it to indicate if the AC was currently on and I think I have a plan for the button. Normally this button is used to reset the Sensibo Sky to factory defaults which means that you use a pin through a small hole in the casing, but I think I could drill out that hole and then glue an extension onto the button, giving me the shortcut action trigger.

Could I go further with some of the pins that are exposed. Is is possible to replace or supplement the LED with an RGB version? Could I mount a button on the face of the unit instead of the side? These are all options opened up by the flexibility of running ESPHome ;)

Another idea relates to some issues I have been having the chromecast speaker I use as my alarm clock and the fact that I now have an IR blaster in my bedroom…

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The latent heat of vaporization

Thursday, November 30th, 2023 at 08:48pm

After my recent posts about the cost of natural gas and how I want to heat and cool my home I got a couple of quotes on installing split system air conditioners in my bedroom and study, the paid the deposit for one which was scheduled to be installed on 20 December, just before Christmas.

Yesterday I got a phone call in the early afternoon saying that they had had some schedule changes and could they start the installation that day with it being completed the next morning. I said yes and long story short I now have air conditioning.

The cheapest way to install a split system is “back to back” which is where the outdoor unit is on the immediate other side of the wall to the indoor unit. This was ok for my bedroom because the outdoor unit would be in the gap between my house and garage, but not ok for my study as that would put the outdoor unit on the north facing wall leading to my front door. I was happy to pay the bit extra for the longer lines and labour to put that outdoor unit over next to the other one.

It is getting quite busy over that side of my house, there is the (now unused) central heating, the two new air conditioner units and soon there will be a new hot water tank and heater.

There is nothing special to say about the units I got, they are Fujitsu with decent energy ratings. I opted to not get any wifi interface as I planned to use an integration with Home Assistant that would send IR commands, in particular the ESPHome IR Remote Climate component.

While I could build and IR receiver/transmitter out of parts, the easier and quicker option was to order a couple of IR Controller Shields, they arrived last week and I started playing around with general IR control (that is another post about replacing the universal remote for my TV/etc) and specifically what ESPHome is like to use. Unsurprisingly it was pretty easy if you are familiar with Linux, Arduino and Home Assistant.

Now onto the hard part which is working out how I want things automated. With the central heating it was a simple thing of “make the whole house this target temperature”, but now the heating or cooling will be set for a specific room. Do I want to take the chill off my bedroom for when I get up, then turn off the bedroom unit while I am working in my study, then finally turning the bedroom back on for when I go to bed? Or just leave the bedroom unit off entirely, only using it on the really hot days?

It is also a convenient week to get it installed as despite tomorrow being the “start of summer” the weather has been below 20°C for the last couple and new few days, then jumping to 33°C mid next week. So I get to experience a range of temperatures and how the systems behave.

One other side effect was due to the layout of my study:

Study in Panorama (June 2023)

While they said they could possibly work over the desk if I cleared a space, I decided that a deep clean behind my desk was overdue so I moved all the NASA LEGO, the printer, the drawers and the desk extensions out so I could pull the desk away from the wall. Giving them room to install the unit and giving me access to clean out the dust and spiderwebs…

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