Minuet: A smart BLDC motor controller for the Maxxfan

[CappyJax]

Sign me up!

I use a couple of Shelly Plus Unis connected to the ethernet port so I can remotely turn the fan on or off, reverse the direction, adjust the speed, and also tell me what the speed is via the voltage sensor. If I have the fan running when I am away and I get a temp alarm, I can close the fan and then turn on the AC from anywhere so my dogs stay cool. But your solution would be so much better, especially with the brushless motor, because I have replaced the bearings twice now.

 

[jeffbrown]

Awesome project! Thanks for all the work and I’d like to upgrade once everything is tested out in the wild.

Little feedback from a skier with the old maxxfan pcb… Consistent water damage to some of the sensors, especially the rf for the controller. I’ve gone through five 5+ boards over multiple campers over the years. Not sure if there’s a way to pot the thing (or however you guys do this stuff as I’m not experienced) and make it more water resistant moving towards water proof. Granted, most probably don’t get exposed to the amount of rain/snow I do while out enjoying their campers, but thought I’d throw the request out there. 🙌

Have you tried applying a conformal coating to the board? It comes in a spray can. That’s my plan to improve water resistance for Minuet. Seems to be a popular request!

 

[jeffbrown]

For a fan located near the back of the van, because it is also recessed up into the ceiling cavity, it’s IR sensor does not pickup signals from the remote when using the remote near the front of the van. I cut open the clear bubble on the IR sensor and extended the wire connections to it in order to lower its position in the fan housing so it could see the remote signals.
So I wonder if your design could use a connector for the IR sensor so it wouldn’t need to be desoldered to accomplish this?

Hmm. It’s tricky ensuring adequate mechanical support for the IR receiver and I’m short on board space so I’m hesitant to add a connector.

How about this? When you order your board, please add a note saying that you don’t want the IR receiver soldered down. Then you can solder your own wires to the pads on the board as you need. Or maybe I can make a little cable for you too.

 

[mercedesstern]

Wow. I wanted to create a custom control board for the Maxxfan Deluxe too, but that saves me a lot of work. I will add a CAN bus controller because I want to control everything in my van by CAN.

 

[tuckie]

I want to control everything in my van by CAN.

I am very much of the same mindset! Have you looked at ESPHome CANopen? (that's my current plan)

What other hardware are you looking at using? I was planning on using a handful of M5Stack products, but they have recently become unobtanium due to the tarrifs (they closed up US shop for now).

 

[mercedesstern]

Thanks @tuckie . I have some CAN hardware already and I was looking for an existing application layer protocol, so no need to develop my own.

I make my own boards with MCP2515s and ATMegas. 8bit at 8MHz clock rate is completely sufficient for home/RV automation. CAN was developed in the early 1980s so the computing requirements are very low, making it ideal for cheap and reliable micro controllers.

 

[CappyJax]

Numerous people on the Winnebago Ekko FB page are now asking about the board after I mentioned it. I think these will sell like hot cakes.

 

[Wrinkledpants]

TL;DR: I designed a replacement circuit board for the MAXXAIR Maxxfan to use a brushless DC fan motor.

I was tired of my Maxxfan squeaking and cleaning it out never seemed to help for long. This seems to be a common problem among owners of this fan. The original fan motor's carbon brushes wear and scrape against the commutator and that makes it squeak. So I fixed the problem.

I found a suitable BLDC motor for the fan, designed a circuit board to drive the motors with an ESP32-C3 for smarts, made adapters for mounting the motor in place non-destructively, wrote some code, gave it a whirr, and basked in glorious silence! As a bonus, I integrated my fan with Home Assistant to control it from anywhere and I attached environmental sensors to monitor indoor air quality.

I've called my new fan controller Minuet as a cheeky pun on "Maxx" because it's minimally noisy.

Soon you'll be able to make one too if you want. Minuet completely replaces the original circuit board and runs ESPHome so you can configure it to work however you want: with or without WiFi, standalone or with Home Assistant, and with peripherals of your choice.

I have open sourced the Minuet hardware, software, and documentation so that folks can reproduce the project and help me make it better. There's still a lot of work to do before it's ready for the general public. Next, I'll be working on a second revision of Minuet. If there's enough interest and help from contributors, maybe we could make a kit!

Project home page: https://github.com/j9brown/minuet
YouTube videos: playlist

I hope some folks here find this useful!
Jeff.

Um - are you selling kits? Because I'll pay for it.

 

[mercedesstern]

Numerous people on the Winnebago Ekko FB page are now asking about the board after I mentioned it. I think these will sell like hot cakes.

It's open source. Just needs someone with knowledge to order the PCB and parts and assemble it.

 

[Wrinkledpants]

It's open source. Just needs someone with knowledge to order the PCB and parts and assemble it.

Yeah I don't have the knowledge or desire to do it. I'll pay for a kit, thought.

 

[jeffbrown]

Um - are you selling kits? Because I'll pay for it.

Awesome! Once I'm done with prototyping, I'll sort out the fabrication and make kits for beta testers. And if that all goes well, I'll make a larger number. It sure sounds like lots of folks want them!

Jeff.

 

[jeffbrown]

Here's a quick update on Minuet!

I have started testing a new motor driver for the fan. It uses a technique called field-oriented control to minimize acoustic noise from the brushless motor. And I'm pleased to report that the motor commutation noise has been eliminated and it is very quiet. I will integrate this new chip into the next prototype and fabricate some boards. And if all goes well, I plan to offer kits for sale.

Quite a lot of folks have expressed interest in getting a Minuet kit so I need to put some thought into how I'll provide updates on my progress and how I'll eventually sell the kits. I'd be happy to hear recommendations from folks who've done this sort of thing before.

Cheers!
Jeff.

 

[CappyJax]

Here's a quick update on Minuet!

I have started testing a new motor driver for the fan. It uses a technique called field-oriented control to minimize acoustic noise from the brushless motor. And I'm pleased to report that the motor commutation noise has been eliminated and it is very quiet. I will integrate this new chip into the next prototype and fabricate some boards. And if all goes well, I plan to offer kits for sale.

Quite a lot of folks have expressed interest in getting a Minuet kit so I need to put some thought into how I'll provide updates on my progress and how I'll eventually sell the kits. I'd be happy to hear recommendations from folks who've done this sort of thing before.

Cheers!
Jeff.

And will it be able to connect to wifi to be controlled from anywhere?

 

[jeffbrown]

And will it be able to connect to wifi to be controlled from anywhere?

Yup! Minuet already does that. You’ll need to provide the wifi network, of course, and Minuet only supports local network communication (there are no cloud servers).

If you want to control Minuet from elsewhere in the world over the Internet then you can do so by way of Home Assistant or some other intermediary on your local network.

And you can modify the Minuet firmware configuration (ESPHome) to do whatever else you might want.

Jeff.

 

[CappyJax]

Yup! Minuet already does that. You’ll need to provide the wifi network, of course, and Minuet only supports local network communication (there are no cloud servers).

If you want to control Minuet from elsewhere in the world over the Internet then you can do so by way of Home Assistant or some other intermediary on your local network.

And you can modify the Minuet firmware configuration (ESPHome) to do whatever else you might want.

Jeff.

Would it be able to connect through Victron VRM?

The way I have it set up now is with Shelly Plus Unis in the ethernet port and I can control the fan remotely. This allows me to leave my dogs in the RV with the fan on, but if it gets too warm, I can remotely close the fan and turn on the AC. Even better would be if it would just automatically close at a certain temp and the AC come on automatically. Would this be possible?

I'll probably order two when available. I can install a second fan to circulate air so I don't need to leave the windows cracked open with the AC on.

 

[jeffbrown]

Would it be able to connect through Victron VRM?

The way I have it set up now is with Shelly Plus Unis in the ethernet port and I can control the fan remotely. This allows me to leave my dogs in the RV with the fan on, but if it gets too warm, I can remotely close the fan and turn on the AC. Even better would be if it would just automatically close at a certain temp and the AC come on automatically. Would this be possible?

I'll probably order two when available. I can install a second fan to circulate air so I don't need to leave the windows cracked open with the AC on.

Hmm. I don’t know anything about the Victron VRM. How does it communicate with the Shelly?

That said, Minuet has the same 8P8C and 6P6C connectors as the original Maxxfan board so you should be able to plug your Shelly into those ports in the same way if you want.

Minuet has a built-in thermostat function like the original Maxxfan board and I have extended it to provide more control over fan speed and direction when running automatically. It would be straightforward to add a mode where it closes the cover as a specific set point. And because the firmware is open source you can pretty much make it do whatever you want.

If you could wire up a signal from your A/C to the fan then you could write a bit of code to coordinate them. There are some spare GPIO pins and an I2C bus available to that could be used for that sort of thing.

I have also been thinking about pairing multiple Maxxfans wirelessly to make it easier to synchronize their behavior. I’m sure folks will come up with plenty more ideas when the boards become available.

Jeff.

 

[CappyJax]

Hmm. I don’t know anything about the Victron VRM. How does it communicate with the Shelly?

That said, Minuet has the same 8P8C and 6P6C connectors as the original Maxxfan board so you should be able to plug your Shelly into those ports in the same way if you want.

Minuet has a built-in thermostat function like the original Maxxfan board and I have extended it to provide more control over fan speed and direction when running automatically. It would be straightforward to add a mode where it closes the cover as a specific set point. And because the firmware is open source you can pretty much make it do whatever you want.

If you could wire up a signal from your A/C to the fan then you could write a bit of code to coordinate them. There are some spare GPIO pins and an I2C bus available to that could be used for that sort of thing.

I have also been thinking about pairing multiple Maxxfans wirelessly to make it easier to synchronize their behavior. I’m sure folks will come up with plenty more ideas when the boards become available.

Jeff.

I don't know how the VRM communicates. I haven't used it yet. I was hoping you might know. The Shellys are stand alone. I have them go to the ethernet port for control, and the voltage sense goes to either side of the motor so I can see if it is running and which way it is running. However, they are problematic. I can hit the button several times before it does anything. I am not sure why. The fact that they only work with a momentary connection is such a pain because you can't just have a rely to open and close.

Is there any single wire that will open or close the cover when that wire is connected or disconnected? That would make it super easy to hook up with the AC and work in unison with other MaxxFans.

Unless you had some really good instructions, I don't think I will be writing any code. I am not that techie.

 

[jeffbrown]

I don't know how the VRM communicates. I haven't used it yet. I was hoping you might know.

I did a quick search for information and it seems like the VRM doesn’t have any provisions for third party expansion but it can control relays integrated into the Victron units.

So potentially you could use a relay to remotely control whether your fans operate using the VRM.

Is there any single wire that will open or close the cover when that wire is connected or disconnected? That would make it super easy to hook up with the AC and work in unison with other MaxxFans.

This is something that could be programmed using one of the spare GPIO pins. I won’t get into the details right now but feel free to reach out again when you’re setting up. It would only take a few lines of YAML.

Because I used ESPHome for the firmware there’s a large community of folks who can help you with custom configuration too. It’s designed to be approachable to folks across a wide range of programming experience.

Jeff.

 

[CappyJax]

I did a quick search for information and it seems like the VRM doesn’t have any provisions for third party expansion but it can control relays integrated into the Victron units.

So potentially you could use a relay to remotely control whether your fans operate using the VRM.



This is something that could be programmed using one of the spare GPIO pins. I won’t get into the details right now but feel free to reach out again when you’re setting up. It would only take a few lines of YAML.

Because I used ESPHome for the firmware there’s a large community of folks who can help you with custom configuration too. It’s designed to be approachable to folks across a wide range of programming experience.

Jeff.

That sounds great! Can't wait to get rid of the ticking from the motor too!

 

[jeffbrown]

Does anyone here have a used Maxxfan Deluxe I could buy for testing Minuet on the workbench? It doesn't need to have a working fan motor or circuit board, just a lifting motor and fan blade is good enough.

Also, JLCPCB has received my motor driver chips and I will be ordering a small first batch of Minuet v3 prototypes soon.

Jeff.