Hi there, in case you have not realized it
yet then let me tell you that this is Part 2 of my automated greenhouse project. So make sure to watch part 1 before watching
this part because otherwise you will get confused pretty quickly. With that out of the way let start off with
me telling you what I learned in the two months of using my automated greenhouse and what
problems I fixed. The first thing I noticed was that the moisture
sensors are pretty useless because they never output any kind of
accurate measurements which
is why I simply got rid of them. Next I added cable lead-throughs because I
actually read all of your comments and admit if I missed something. I also 3D printed a new housing in white for
my Temperature sensor because using a black enclosure in direct sunlight kind of distorted
the measurements. Last but not least I added a better antenna
to the LoRa board which I positioned on top of the greenhouse to achieve a more stable
connection to my router. And those were bas
ically all the changes if
I exclude that I also added a small script which translates the hex values to decimal
and I have to say that I am pretty happy receiving the temperature and humidity data without
any problems because it lets me easily know when I have to open the window or door to
ventilate the greenhouse. And it even seems like all my tomatoes, sugar
melons and one water melon agree with me on that. But wouldn’t it be awesome to have an automated
motorized window opener which like the
name implies open and closes the window whenever
I tell it to do so through the Things Network site. Well in this video I will show you how to
do just that, so let’s not waste any more time and let’s get started! This video is sponsored by JLCPCB! Feel free to visit their website JLCPCB.com
to not only find out what awesome PCB and Assembly services they offer but also to easily
upload your Gerber files and thus order affordable and high quality PCBs. First off I have to say that my initial plan
was to also incorporate an automated watering system but I quickly realized that I need
to visit my greenhouse almost every day and thus automating this process would have been
kind of pointless and thus I scratched it. With that out of the way let’s think about
the motorized window opener which consists of a mechanical part where we have to decide
on a motor type and create a suitable mechanical system consisting of motor holder, gear and
gear rack and an electronics part in which we have to f
igure out how to drive the motor
and how to control it through LoRa and the Things Network. Let’s begin with the mechanical side by
choosing between these three motor types: a BLDC Motor, a Stepper Motor or a DC Motor. Now the biggest challenge for the motor will
be the required holding torque which is required to hold the window in the opened position
and not let it roll back down. That means the BLDC Motor is out because common
ESCs which are necessary to power them, do usually not come with a
holding torque option. Stepper Motor drivers however do come with
such an option and therefore feature suitable holding torque. But the catch is obviously that powering the
stepper motor would require quite a bit of energy and since we are working with solar
power and a battery we should definitely avoid that which means that the stepper motor is
out as well. And that brings us to the DC motor which at
first sight does not come with decent holding torque. But if we take a DC motor whose RPM of
5000
gets reduced to just 100 through a gear system then you can see that it suddenly features
quite a lot of holding toque which I even cannot overcome with my hands. And due to this gear system and later powering
it with only 5V, I will not even have to alter is RPM electrically which makes it perfect
for our window opener. So next I measured all the dimensions of the
motor as well as the space between the available mounting holes next to the window and through
this knowledge created this moto
r holder in which the motor will later fit snugly and
can be locked in place with two M3 bolts and nuts. Next it was time for the gear system for which
I used the McMaster-Car component library where I chose a fitting plastic gear and gear
rack. After then extending the gears mounting hole
a bit according to the dimensions of the motors rotor, I also added a 3mm hole to it to later
hold it in place with a grub screw and then continued by shorting the gear rack a bit. As you can see those two par
ts can later be
used to slide the rack forwards and backwards and thus opening and closing the window but
as you might already have guessed this rack cannot float in midair which is why I also
designed this case for it. And with that being done, all the mechanical
components were pretty much done and thus I 3D printed them all with my Prusa 3D printers
which took around 4 hours in total. As soon as that was done I assembled the gear
system for testing purposes and as you can see by alternatingly
powering the motor, the
rack slides forwards and backwards without a problem which brings me to the electrical
section. To turn the motors rotor left and right we
need to be able to change the current flow through it which is why we need such an H
Bridge circuit and at least two digital pins of our microcontroller. If the left side is high and the right side
is low, current will flow from right to left and if the left side is low and the right
side high, current will flow the other way which ba
sically means this circuit should
do the trick. But while searching for suitable MOSFETs,
I noticed that I didn’t have any logic level P Channel MOSFETs lying around which are definitely
mandatory when working with such a 3.3V system. But instead I found this L293D IC which actually
includes an H-Bridge and can be controlled by 2.3V logic levels, perfect. To test it, I soldered a fitting IC socket
to a piece of perfboard, created some solder connections and finally hooked up the motor
according
to this little schematic. After then inserting the IC and connecting
the power lines to 5V which is a voltage that is also available in my greenhouse, we basically
got two input pins to work with. Depending on which one gets connected to 5V
or later 3.3V, the motor rotates one way or the other way and as you can see everything
seems to work just fine. So next I got myself the same Arduino LoRa
board from part 1 of this video series and connected the input pins of the motor controller
to pin 3 an
d 4 in addition with 300kohm pull down resistors but you can just follow the
finalized wiring diagram of this projects if you are interested in creating something
similar. After then adding this new LoRa board to the
things network site, I adjusted the code of this test device a bit so that it always uploads
the same temperature and humidity data. And after hooking an FTDI breakout board up
to it and uploading this new code you can see that the things network gets the data
successfully and here
we can actually send over data through a downlink but all the Arduino
code registers is how big the received data was in bytes. So I simply edited the code in a way that
it rotates the motor one way if it receives one byte and it rotates the other way if it
receives two bytes. Of course I also implemented a delay so that
the motor only moves for a short time and the motor can also not rotate the same way
twice in a row and the Arduino will also from now on send over the status of the window
with
99.9 standing for being open and 00.0 for being closed. After uploading this finished test code and
powering everything up, I sent over 1 byte which promptly let the motor spin one way
and afterwards I sent over 2 bytes which lets it spin the other way, perfect. That means it was time to head into my garden
to firstly secure the motor mount with motor and gear system next to the window and then
soldering a wire to the motor which I guided into my electronics chest through the help
of wire pedes
tals and zip ties in which I then connected the motor wires to the motor
driver IC which I then obviously hooked up to the LoRa board. After then using adhesive tape to mount the
window opener to the window, I uploaded the finalized code and as you can see the system
still sends over the correct greenhouse data but now we can also remotely control the window
through LoRa and the internet, brilliant. With that being said, I hope you enjoyed this
video series and learned a thing or two. If so don’
t forget to like, share, subscribe
and hit the notification bell. Stay creative and I will see you next time.
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