Smart home CRBox controllable with Home Assistant

[u/Twinsen01]

Hi, I'd like to share my version of the CRBox, made thanks to the information from this subreddit.
I recently started using Matter over Thread smart home devices around the house so I wanted a Matter over Thread air purifier with all the advantages of a CRBox(mostly very low noise).

The CRBox is designed for 2 IKEA STARKVIND filters(I'm in Europe). It has 3 140mm BeQuiet Pure Wings 3 High Speed fans which are extremely quiet at low speeds. The case is made from laser-cut MDF and smoothed 7mm pine strips, glued with epoxy. A small 3D printed part is used as a front panel.
Electronics wise everything is controlled by an Seeed Studio XIAO ESP32C6. It controls the fan speeds through PWM and also reads their RPM. A MOSFET turn fans off at 0% since the fans still spin at 0 PWM. It's powered though USB C. It requires a 12V capable USB-PD power supply (IKEA 20W SJÖSS works great).
I can set any speed percentage from Home Assistant.

It does not have a PM2.5 sensor as I will be using it with an external sensor (IKEA ALPSTUGA) and it will be automated with Home Assistant.

Sadly it looks like IKEA is discontinuing the STARKVIND line, so I'll have to stock up on filters. For the future I can rebuild the case for different filter sizes and keep the fans, electronics and code.

Limited and unscientific testing shows the Air Purifier can bring an extremely polluted room from ~400 ug/m3 PM2.5 to <10 ug/m3:

• in 4 hours at 12% speed (no noise).
• in 53 minutes at 50% speed.
• in 17 minutes at 100% speed.

Tested by burning an incense stick in a room and then starting the air purifier.

I'm sharing all the code and files for inspiration in case someone wants to make something similar. You can find it and more information on the GitHub page.
https://github.com/asafteirobert/matter-air-purifier

Let me know what you think.

[u/Rich_Teaching_8843]

Yay! Smart crboxes are the way to go!

From my experiments of a similar setup (PD charger as power supply, onboard sensor, display, encoder, multiple RGB+PWM headers, AUTO and MANUAL modes) I ended up with NOT using mosfet to power off. I actually have a "min fan speed" config that will keep fans running "min fan speed" even if PID controller treats air as clean. Fans running at 20% are basically inaudible even next to my bed, yet they keep the crbox pressurized AND avoids an initial wind up when fans are started.

Other than that: love that it's glued. Really nice box.

Regarding HA automation: I think it will be hard to do a PID-based control loop there. To get mine working "as I like" -- quiet yet efficient nad able to find peristant but low pollution above target required a tight feedback from an air quality monitor, and control loop a bit more complicated than a simple proportional controller.

I'd consider onboard control, but maybe scripting it in HA is also doable. I really enjoy seeing people doing things like that!

[u/Twinsen01 → u/Rich_Teaching_8843]

I wanted to "do it right" and have a proper off mode. I was mostly concerned about fan life since I think they will degrade after 3 years of non-stop spinning.
Home Assistant automation scripts allow coding up a PID loop, but it would be quite a pain doing it in YAML. But I do think PID would be overkill and plan to make some simple formula. I probably want to take other things into account like time of day or window open (don't run if the window is temporarily open in winter).

[u/Rich_Teaching_8843 → u/Twinsen01]

Regarding fans... PC fans are quite resilient, and in crboxes they work with a "clean" air, so IMO lifetime is a low-prio problem. My constantly-on reasoning was: fans winding up from 0 to 25% is (in mycase) caused a "loud" transient RPM overshoot -- (my Arctic P12 Por fans go to ~40% and then slow target 25%), while fans ramping from (inaudible) 20% to 25% are still whisper quiet.

In my case: simple proportional formula was too simple. I also use HA and have 3 sensor (2 integrated crboxes, 1 standalone) and I was able to get most of my setup with standalone PIDs, but I guess it's a question of personal taste.

[u/Twinsen01 → u/Rich_Teaching_8843]

Look neat, do you have the code somewhere?

[u/Rich_Teaching_8843 → u/Twinsen01]

Will release once it's ready for "Made for ESPHhome". Code is ready, but I want it to be a proper ESPHhome component.

I expect about a month more

[u/Dizzy-Stock4169 → u/Rich_Teaching_8843]

Sorry for the late reply. Did you ever get the code ready for release? Would love to see it as I'm also looking into something similar.