Hi there! Just wanted to show you how I integrated the air purifier into Home-Assistant. Now I’m able to adjust the fan speed, switch it off and on and also see if I need to replace the filter. Inspired by https://www.reddit.com/r/ikeahacks/comments/m0rdlw/förnuftig_but_it_has_rest_api/. Just to make it clear, you’ll loose the warranty and my hack is not supported by IKEA. Do it on your own risk.
This tutorial is not for a beginner. I assume you know how to connect some wires, how to use a step-down-converter and upload some code using ESPhome.
You need:
- 1x Wemos D1 mini or a similar ESP8266 or ESP32 device.
- 1x Step-Down converter to convert 24V down to 5V for the ESP32 (common Gnd)
- Some wire and hot glue
I recommend to unsolder the LED next to the antenna on the Wemos D1 mini or it will light up depending on the position of the rotary switch.
Ok, let’s start. It’s quite easy to get access to the PCB. Get the front off and the filter our (as shown in official tutorial). Now loose the two screws next to the LED and remove the inner part by lifting it up.
Loose the two screws fixing the PCB and pull out the knob on the other side. Below the knob is a flat nut you have to remove. Now take out the PCB and disconnect the two connectors.
First, solder some wires to the back of the socket where 24V is connected to the PCB. This wire goes to the step-down converter where it is converted to 5V and connected to the Wemos 5V input.
On the top side of the PCB (where the knob was), cut away the connectors for the rotary switch near the PCB (see picture for which legs you have to cut). Take a sharp side cutter and cut each leg individually next to the PCB. Bend the legs up and solder a wire to each of them. Sorry for the bad picture, I took it after applying hot glue… You don’t need to solder a wire to the leg opposite to the small red push button on the PCB – only 4 are needed here. Connect them to D1, D5, D6, D7 on the Wemos. D7 ist next to the one we don’t connect.
On the other side take out the remaining parts from the rotary switch you cut on the other side to make the holes free. Solder 4 wires on them. One is a bridge to ground, the others also connect to the Wemos (see label on the following picture). The last wire needs to be soldered to the LED or the resistor next to it (red circle on image).
It looks like the controller on the PCB checks all the positions of the rotary switch from highes power to off. Highest value “wins”. So we don’t ever need the actively select the “off”-setting. This is the one we connected to Gnd. Don’t worry about the “short” to Gnd. This is how the rotary switch worked too.
That’s it! Secure all the wires using hot glue and put all the parts next to the existing PCB. I managed to put the step-down converter behind the Wemos D1 mini, it’s barely visible. Use some more hot glue to fix it to the case. Make sure you don’t short out anything.
Before closing it, upload following ESPHome configuration to the Wemos.
esphome:
name: $devicename
platform: ESP8266
board: d1_mini
substitutions:
devicename: esp82-fornuftig1
friendly_name: FORNÜFTIG
# Insert your SSID and Your PWD after inital setup
wifi:
networks:
- ssid: !secret wifi_ssid
password: !secret wifi_password
# Enable logging
logger:
logs:
# Make adc input less verbose
adc: INFO
# Enable Home Assistant API
api:
password: xxxxxxxxxxx
# Enable OTA upgrade
ota:
safe_mode: True
password: xxxxxxxxxxx
sensor:
# Read LED from adc input 10 times per second
- platform: adc
pin: A0
internal: true
id: led_internal
update_interval: 100ms
accuracy_decimals: 1
filters:
- delta: 0.1
on_value:
if:
condition:
lambda: 'return x < 0.2;'
then:
- binary_sensor.template.publish:
id: led_sensor
state: OFF
else:
- binary_sensor.template.publish:
id: led_sensor
state: ON
binary_sensor:
- platform: template
id: led_sensor
name: "friendly_name Filter"
device_class: problem
- platform: gpio
internal: true
id: in_d1
pin:
number: D1
mode: INPUT_PULLUP
inverted: True
on_press:
- fan.turn_off:
id: fan_internal
- platform: gpio
internal: true
id: in_d5
pin:
number: D5
mode: INPUT_PULLUP
inverted: True
on_press:
- fan.turn_on:
id: fan_internal
speed: 1
- platform: gpio
internal: true
id: in_d6
pin:
number: D6
mode: INPUT_PULLUP
inverted: True
on_press:
- fan.turn_on:
id: fan_internal
speed: 2
- platform: gpio
internal: true
id: in_d7
pin:
number: D7
mode: INPUT_PULLUP
inverted: True
on_press:
- fan.turn_on:
id: fan_internal
speed: 3
output:
- platform: gpio
pin: D2
id: gpio_d2
inverted: true
- platform: gpio
pin: D3
id: gpio_d3
inverted: true
- platform: gpio
pin: D4
id: gpio_d4
inverted: true
- platform: template
id: fan_out_internal
type: float
write_action:
if:
condition:
lambda: 'return state < 0.1;'
then:
- output.turn_off: gpio_d4
- output.turn_off: gpio_d3
- output.turn_off: gpio_d2
else:
- if:
condition:
lambda: 'return state < 0.4;'
then:
- output.turn_on: gpio_d4
- output.turn_off: gpio_d3
- output.turn_off: gpio_d2
else:
- if:
condition:
lambda: 'return state < 0.7;'
then:
- output.turn_off: gpio_d4
- output.turn_on: gpio_d3
- output.turn_off: gpio_d2
else:
- output.turn_off: gpio_d4
- output.turn_off: gpio_d3
- output.turn_on: gpio_d2
fan:
- platform: speed
output: fan_out_internal
id: fan_internal
name: "$friendly_name Fan"
speed_count: 3
Test it out! The rotary switch does still work but it is also possible to control it from within Home-Assistant. The rotary switch will (of course) not move when controlled from Home-Assistant. But as soon as you move the switch again the corresponding setting will be used.
My first tutorial here, so please be gentle :). Feedback welcome!
Edit: See post IKEA FÖRNUFTIG in Home-Assistant - #32 by RubenKelevra about how to integrate it into energy monitoring.
But it works with home assistant and kinda working with the knob, I’ve sat both input d5 and d6 to fan speed 1 and then d7 to fan speed 2 (speed 3 is so loud anyway 
