I bought a palm tree which does not like wet and cold, so I am building a small conservatory around it, with a 4 m2 roof that automatically opens when it gets too hot, and closes when it gets too cold.
I watched a lot of YT videos, and your group came up more than once with good advice.
I think I need the following:
230V to 3,3-5V power, can this be a phone charger?
USB-A to USB micro B cable
Raspberry Pi Pico 2040 WH (first model Pico with Wifi and headers). There is a temperature sensor on the Pico, but most videos I saw mention a BME280, can I use the internal temperature sensor?
a BB400 breadboard
cables between Pico and relay, and relay and linear actuator
a relay/servo that powers 230V, and gets logic from the Pico PWM ports. Preferably a Mosfet device so that it does not require cooling or throw off the temperature sensor on the Pico. What would you recommend?
A linear actuator that can lift a 100 kg roof and accepts PWM signals to expand/contract about 20 cm. The roof is a wooden frame with polycarbonate plate, held at the top by 3 heavy duty hinges, and pushed up in the center by the linear actuator. What would you recommend?
With the Pico I want to monitor the temperature, and via the Wifi show a graph with today’s temperature every hour sampled. This can be from my Android phone or desktop PC.
When the temperature drops below 5 deg C close the roof.
When the temperature raises above 10 deg C open the roof.
This must be fully automatic as I use winters to go on long tropical holidays, and stay home in our summers as it is quite nice then.
I foresee that the roof will open every day when the sun shines on the conservary and heats it up, and in the colder nights will close every day.
If the roof is 100 kg and is hinged at one side and pushed from the centre, the actuator will have a load of more than 100 kg. If you only require the roof to be either open or closed then a motor and cable would be simpler and cheaper than an actuator - something like a garage door opener, with a counterweight.
Good advice, I’ll look into garage door openers.
I had also already considered using a scissors carjack with a motor that spins the threaded rod inside the scissors jack. That requires a rotational motor to turn so many seconds. But how to deal with it stopping when closing the roof and not pulling on the roof if already fully closed?
Welcome to the forums! This sounds like a fun project, a great mix of hardware and software. I’ll tackle each of your questions.
This can just be a phone charger, the Pico will accept 5V through its USB port. Whatever you use to actuate the ceiling will likely want more than 5V so you will need a 12V supply too.
The micro B cable can be used to both program and power the Pico.
That’s a great board, the onboard temperature sensor isn’t great for measuring ambient temperature so use an external temp sensor. Any of the BMP/BME series chips will do this just fine.
@Jeff105671’s recommendation of a garage door opener is brilliant. You will just need to find something that you can communicate with.
There are some neat ways you can solve this. Microswitches or magnetic switches can be great to use as an end point. This usually will involve a collision to close it. A distance sensor could also be used to slow its approach first.
You can put sensors on the roof itself or on the actuating mechanism to detect the position and control the operation. But if you use a motor and cable then you have an alternative option of fittings on the cable which operate a contact. So the controller only needs to be a SPDT switch that turns on the power to move in the required direction, and the physical contact operates a switch to turn it off at the end. This can be done with a generic HVAC control, available very cheaply on line, which closes one relay contact when the temperature falls below a certain value (for heating) and closes a different relay contact when it rises above a certain value (for AC). See, for instance: Digital LED Temperature Controller Wireless Fan Coil Thermostat
These products typically have hysteresis control that enables you to ensure there is no overlap in the ON states. You would need to confirm that the hysteresis range is adequate to ensure that the state does not change during operation. Products mentioned in this reply are examples only and are not a recommendation.
Hi Jack, Cas
Please tell me you are not going to use a breadboard in the final build.
If you are it is my humble (note the “humble”) opinion you are asking for trouble downstream. How much later this trouble would occur depends on lots of things.
Cas:
This sort of thing I think can best be handled with limit switches at both ends of travel. To ensure complete safety “limit switches” really need to cut power. The type of “limit switching” that involves stopping a motor with software control is not particularly “safe”. The down side of cutting power is reversing the motor, with the power cut with a switch it is not possible to power the motor in reverse until the switch makes again.
This can be overcome by using a SPDT limit switch and diodes. Also you can’t have a motor over run the switch so it has to be effectively braked to stop pretty much instantly.
If you decide to go down the limit switch path I have a tried and proven circuit that works very well which can post if required.
That is a pretty heavy roof. Personally I would be tempted to use an aluminium frame, even a steel one would probably be lighter than timber.
What is the PWM for. I think the actuator or other device would be quite happy with a simple ON/OFF system (switch or relay). PWM is more commonly used for a variable speed control.
The use of a Pico for control is probably pretty easy and fun (also educational) but there are plenty of ready made temperature controllers around, Jeff has linked a couple. Advantages are usually built in relays. In your case you would probably need to arrange motor reversal which is not a real drama. Also needed is some sort of sensor. A common one is a K type thermocouple. It is a bit hard to tell but the top one Jeff linked I think could be supplied with this.
The game changer could be cost. Known branded units like Honeywell etc tend to be pretty expensive. I don’t know what the Ali Express one linked is like quality wise but at $10.29 It could be a goer even for an experimental role.
A look at Element 14 web site would give you an idea of this.
Cheers Bob
The breadboard is great for prototyping for the sensor and configuring a motor driver. Assuming that this board doesn’t move after its installed I can’t see too many issues arising.
Hi Jack
As long as the breadboard is used in a favourable environment.
I wouldn’t like its chances in a situation like a hothouse or greenhouse where the humidity might get up a bit. I think the contact plating material might suffer somewhat.
I could be quite wrong here and this aspect might be better than I think.
Any issue is one too many with the end product. Particularly when can has stated
and the system will be completely unattended.
Cheers Bob
This would be an issue for most of the electronics, even if it wasn’t a breadboard you could still solve it similarly. You can get quite good waterproofing from lots of store-bought containers and some silicon.
Agreed but we can tackle those as they arise. When the product is on the table fixes can be done around it. Built-in redundancy is another solution to ensure that it keeps working when parts fail.
That would probably be the end of the breadboard as far as any changes are concerned.
Can’t beat soldered joints (done properly).
Anyway, go for it.
Cheers Bob
Rather than the BME280 I would recommend a SHT40, it is a bit more tolerant of humidity in comparison to the BME280.
Generally speaking linear actuators are quite expensive (especially one that would be able to reliably lift 100kg) to take up some of the burden a gas strut like you would have in boot of your car would mean you can use a linear actuator that is less powerful to help cut down on costs. This website would give you an idea of the type of strut that you would need.
I will swap out the BME280 for that SHT40 and also loose the breadboard, to use soldered connections.
I plan to put the pico and all other boards in a plastic container. Should I include some ventilation holes covered with netting to keep it from heating up too much, but no insects inside.
Are there generic wiring sets with connectors? I saw Stemma QT connectors. Is that good?
Qwiic, Stemma QT (has to be the QT version) and Piicodev are all the same size and are interchangeable. As for ventilation holes, they probably won’t be needed but if you’re planning on putting the temp sensor in there you will need “free air” otherwise it will give you incorrect readings.
Don’t get me wrong here. No need to “lose” (loose ??) the breadboard just yet. These are very useful in the experimental or development stages any and alterations can be easily done.
It is just that I personally would not use one in any sort of finished product. I would build up on one of the many types and styles of proto boards around. Are have a couple of “Makerverse” types. One thing to be careful of here is the one with tracks is double sided so if you cut a track you have to cut on both sides of the board.
But each to their own solutions.
Cheers Bob
This one (double sided)
Makerverse Protoboard 30 Row
has a similar layout to a breadboard so you could work out your component layout on a breadboard and transfer it to the port board.
There are some others these days. Search “Makerverse” on the Core store site.
Those are really neat! I’ve never seen them before but it makes total sense that they exist.
I do worry you may lose some flexibility here, as an electronic system could be adjusted based on specific temperature requirements and other desired factors. Additionally, @Cas283742 mentioned that they want a reporting system, to graph the temperature over time, which would be a fairly simple addition using the previous solution.
That being said, the simplicity of those actuators is pretty great and is likely a decent bit cheaper than using an electrically actuated system. The only compatibility issue I can see is the weight limit. The actuator needs to lift 100kg, and from what I can see there is no weight rating on the two items you sent.
I saw those before I decided on building something myself, for the following reasons:
My roof was going to be too heavy,
The gas element was not recommended below 0 Celsius,
I would like more control over the exact open/close temperatures.
Based on the comments above, I did change my design. I decided to put the 3 hinges at the bottom of the roof, and the scissor jack at the top of the roof. This means the jack only has to carry half of the weight of the roof, and I bave a sturdy bottom support fot the jack.
I don’t know how to add a picture to this post, so I made my profile picture a picture of the palm tree (Sabal Palmetto) with the conservatory so far.
You possibly could get more rain water in that way. But this may not matter. Just something to think about.
100kg is a pretty heavy lid. I would still look at reducing this weight by using aluminium or steel frame. Windage is something else. Is it very windy at your place. Although with this it might not make much difference which way the roof opens.
Cheers Bob
Thanks for the photo! For future, you can add photos by dragging them over the editing box while making a post, or using the button at the top of the edit box with the small up arrow.
Thanks for everyone’s additions to this. Interesting project to keep up with!
