Arduinos In The Grow Room: My Project

odam2k said:
This mornings immediate project, fix my noisy Weller WESD51 soldering station. It's been a faithful tool for quite a few years, but last year it started making a loud buzzing noise. Google led me to tightening the bolts holding the transformer in place, and that solved it, for a while... Eventually the buzzing grew louder, became more annoying.... So this morning I smothered it in epoxy resin.... (just the transformer) to see if that will keep it from rattling.... I hope so, I don't think I could go back to a cheap iron and I'm in no position to replace this one...
Click to expand...


I sat down this morning to do some soldering, and thought how nice it was, the only thing buzzing was me :) LOL
About 15 minutes later, there it was, just faint, but still there. Seems the epoxy didn't work...
 
Latitude17 said:
Would love to see what you come up with on this one, as I've hit a creative wall myself.
Click to expand...

I know, sometimes I sit here just trying to think of something new, but that's usually when I just go lie down for an hour or so, I usually come back with some ideas... I've gotten so far away from regular sleep patterns, I don't usually sleep more than an hour, maybe a couple if I'm lucky, then up and at it for 3 or 4 hours, then "nap time" again :)
 
odam2k said:
I'm tossing around a new idea... using two sets of sensors in a pot, one about an inch off the bottom, and the other about an inch under the top of the soil. Since each is powered on only when taking a reading, they won't interfere with each other, and I could share a common ground so it's still only 3 wire.... I've got about 50M of servo wire coming :) With this setup, I could build it right into the pot somehow, and have a much better idea of the plants water needs... Of course, this will need some significant database, and coding changes, but I think it might be worth it....
Click to expand...

Hmm, keeping this to 3 wires is fairly important, I can just use regular servo wire. Nice and neat... So, that means 2 powered wires (separately) and one shared ground wire. So a powered "probe" goes near the top, and another near the bottom of the pot... What should I do with the ground? One single ground about mid-depth? Split into 2 so there is one near the top and one near the bottom powered probe? I guess I can't just stick em to the side of the pot either since I'm sure it dries out there fairly quickly... I guess a "stake" long enough to reach the bottom of the pot with a positive probe top and bottom, and ground in the middle... or the whole stake is grounded? hmmm, where's my bong...
 
Here it is, prototype #1...

The nails are galvanized, but the tube is aluminum, hope that works ok as the ground. I won't get to test it till later today. The nice thing is, the nails are powered by digital ports, and I only need one analog port to read two sensors (common ground) The Wemos Mega has 53 digital ports, way more than enough for 16 analog inputs...

IMG_20181228_074505.jpg
 
I've found that PVC does better in my grow media (Perlite) than something like Aluminum - the salts make for some interesting chemical reactions.

Your design has the spacing much farther apart than others I've seen - have you found that it works better?
 
Each "sensor" is one nail and the aluminum tube... so there are 2 sensors on that single tube... The distance from the nail to the aluminum is small... When I was just using 2 nails on the end of wires, I often had the nails about 6-8 inches apart. When I first bought the premade sensors, I was surprised how close together they were...

I got a chance to test it quickly, and I don't think the aluminum works as well as another nail, so a bit of redesign in in order.

Also, a bigger problem, it still takes 2 analog ports to read 2 sensors. I guess I don't have my head wrapped around this yet.
 
Latitude17 said:
You really should look in to the i2c spec, it solves your port limitation issues almost completely.
Click to expand...

I'd still need to create an i2c hardware interface for the sensors, and write the code... I'm still convinced I can do it with a single pin because the voltage divider is on the ground wire, and there is a common ground on the 2 sensors.
 
Ok, code changes are done, and initial testing is a success! The dual sensor probe works! I can read the Top and Bottom moisture level using a single analog pin. Of course, it takes 2 digital pins, one to power each sensor, but the Mega has 53 digital pins...


Capture.PNG
 
Now all I need to do is add an I2C interface, perhaps it could also handle switching the power on/off for each sensor...
I guess it's time to make up a bunch of these Dual Sensor probes... Will have to visit the hardware store to find a suitable "rod" to mount the nails on...
 
Once you get the i2c rolling, it would be neat if you could make a multi-point sensor that could take readings every inch or so. I'm not a soil guy myself, but I'm fascinated by your progress!
 
I've been reading about cable length limitations for I2C, and considering it was originally developed for chips to talk to each other on the same PCB, I could be stretching it. I think my longest current wire for a sensor is about 15 feet.

I guess with I2C I will basically stretch one wire through the space, with connectors along the way to plug in the sensors?
This would give the shortest TOTAL length. (It would probably be about the same as my longest now, 15 feet.


Capture.PNG



Something like that? That would actually be nice, I could neatly run the one wire down the length of my flower area (I have 3 rows of 6 pots), sure would look a lot neater too!
 
I have a bunch of Pro/Mini's lying around, and I can't wait, so I'm going to use one as an I2C Slave, with the sensor hooked up to it. The I2C Master will call the slave using it's address, tell it to scan and report. The pro/mini is capable of powering each sensor individually, in fact, it could support up to 8 actual sensors. In my current config, that means if I spaced out 6 pro/mini's along my main wire, I could easily plug 3 of my "Multi-Sensor" probes into each. (6 pots x 3 rows).

I do like the idea of EVERY Sensor (Probe) having it's own I2C address. Right now, I've assigned an ID number to every sensor, so that would be it's I2C address, but that means each sensor has it's own microprocessor. Of course, this means each Probe could have up to 8 sensors on it, so measuring moisture every inch or so would be feasible.

Now my mind wanders to adding bluetooth to each microprocessor, but you'd still need power to each unit, so there isn't really any benefit.
 
Here it is! Plug the sensor in, plug this into the I2C bus (wire from the main Module) and it should work...

This is just the hardware end of things, I still have to write software to communicate back and forth, but I've got it all coded in my mind :) Perhaps I'll sleep on it for tonight, and tomorrow, finish it off...

I2C_SensorModule.png
 
Latitude17 said:
Once you get the i2c rolling, it would be neat if you could make a multi-point sensor that could take readings every inch or so. I'm not a soil guy myself, but I'm fascinated by your progress!
Click to expand...

Perhaps a rod with galvanized wire wrapped around it every couple inches? Alternate + - + - + - + - + - +

With my Pro/Mini I2C module, it could support 6 sensors (A4 and A5 are for I2C)

Of course, 6 "sensors" per "Probe" will require more database and code changes... :nomo:
 

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