OK, I'll admit it - I tend to kill plants.  I set them on a sunny window sill, give them an initial drink of water, and promptly forget to water them ever again.  Having grown up in a world where objects tend to beep or blink for my attention, the stubborn silence of the average houseplant dooms it to an early death under my care.

But no more!  In an effort to solve this problem, and have a bit of fun at the same time, I created the Plant Whisperer.  This little device measures the soil moisture every two hours, and reports its status to anyone who might be within earshot - that's right, it talks!  The message content depends on the soil condition.  For example, if the soil is too dry, the plant might say, "I'M THIRSTY!  WATER ME!"  If the moisture is okay, it might say "I'M A HAPPY PLANT!" - or maybe something funny like "I SUGGEST YOU BECOME A CARNIVORE."  It is also capable of detecting the ambient light level and commenting on that, as well.

Did I mention the cool retro robot voice?  Yeah, who wouldn't want that on their houseplant?

The Plant Whisperer is based around a Parallax Propeller, which makes real-time text-to-speech easy to implement.  Other major components include a two-channel ADC, a two-hour timer IC, a load switch and an audio amplifier.  In total it costs about $30 to build.

Step 1: The Design & Schematics

Included below are the schematics and PCB artwork, so that you may build the PCB required for this project.  It is a double sided board (no getting around that, I'm afraid!)  I made my board using the photo-etch method, which is the only home method capable of getting good results for surface mount parts.

How it Works:

At the heart of the Plant Whisperer is a Parallax Propeller.  It's one of the only microcontrollers out there that is powerful enough to handle real-time text-to-speech.  Upon start up, the Propeller initializes the external ADC (since it has no ADC of its own) and the audio amplifier.  After a brief period of time, the ADC is polled for soil and light level information.  Depending on the results, a random phrase is selected from a list and spoken to anyone who might hear it.  However, it will not speak if it's dark - this plant might be needy, but it won't wake you up when you're sleeping!  When the Propeller has spoken its message, it sends a signal to the timer to restart its timing cycle.

In order to conserve as much power as possible, an LTC6991 "Timerblox" low-frequency oscillator is used to turn the entire circuit on and off.  It is set for a period of about two hours, though it is capable of timing up to 9 hour intervals!  So, every two hours the timer output goes high, which turns on a load switch.  This activates the rest of the circuit.  When just the timer is running, the Plant Whisperer draws only 75uA (yes - microamps!)  The timer allows the rest of the circuit to stay on for up to an hour, though it's usually on for only a few seconds.

The moisture probe is pretty straight forward.  A voltage is pushed through the soil, resulting in a small current.  That current is amplified and converted to a voltage by a transistor.  The voltage produced will be somewhere between 0V and 3V, depending on the soil conductivity.  That voltage is measured by a Microchip MCP3202 ADC, which then relays the value to the Propeller.

A small 0.25W amplifier is included to drive the speaker.  It is activated by the Propeller when needed.

A single LED is used for status; it turns on at the command of the Propeller.

There is a single switch, which is used to manually turn on the Plant Whisperer.  When you press the button, it overrides the timer's internal timer, and allows the rest of the circuit to power up and do its thing.

Two AAA batteries are used for power.  With a capacity of 1250mAh, the Plant Whisperer should have enough juice to run for months.

The Design

My original design was square and BORING.  I hope you like the paisley-type swoosh I came up with.  The Plant Whisperer is designed to mount directly onto the front of a small planter, with the moisture probes mounted permanently into the side of the planter.  If you'd rather not do it this way, two small connection points are provided to connect a set of test probes with wire.
<p>great stuff, amazing skills with the circuit board.!! are you familiar with my <a href="http://www.instructables.com/id/the-Plant-Doctor-family/" rel="nofollow">work</a>.? </p><p>.<br>it can e-mail you once it is thirsty, cold/hot, asleep etc. - also changes color for nearby users.</p><p>it also collects/graphs data on the cloud - the best part is that it is 100% solder free to build.!</p><p>.</p><p>thank you for sharing, i really like your posts</p>
After I downloaded 12 blocks from the link you gave, my antivirus said it was &quot;WS.Reutation.1&quot; and automatically removed it. Is the program safe or do I need to use a different link?
I'm afraid you'll need to contact the creator of 12blocks about that! I got no virus warnings way back when I downloaded, but it has been updated a few times since then. Good luck!
Ok, thanks.
hey look i just want to make a very basic model of this one....its like using a humidity sensor and two diff buzzers and one atmega 32 or sumthn..<br>so i can use a internal ADC of that and thru programmin set the conditions and make the buzzer work......!!!
Crazy idea popped into my head. The plant calls you or sends an e-mail when you neglect it for a long time.<br><br>Example:<br><br>Hmm I'll go check my e-mail<br><br>*E-mail from Mr.Plant@plant.net*<br><br>&quot;I'm thirsty!&quot;<br><br>Oh!<br><br>*Waters plant*
Not so crazy! Do a search for &quot;botanicalls&quot;. ;)
nice project really cool <br>Do you no how 2 make a decibel reader???
Thanks!<br><br>Nope, I don't know how to make a decibel reader. Have you looked here on Instructables, or on Google?
Fantastic project! I need to make on of those immediately!
Great, I can't wait to hear a plant speaking Dutch! I'm working on a minor update to the pcb though, so wait a day or two before you start.
I'll sent you Dutch lines hehe
omg i have been looking for something like this for a while. but this is too much for me. i was wondering though could you make a simpler one that just flashes LEDS or changes color to represent the moisture. ( red LED for to dry, blue LED for too wet, &amp; green LED for just right. i would really appreciate it. or any help.
Well, you can buy those at any hardware store if you want one right away... <br><br>What are you able to build? Can you make your own circuit boards?
well i havent really seen anything like what i want in stores. and i've never made my own circuit boards before but i can learn how. if you have a circuit for something like this i would like to see it and i would definitely try to make it.
Well, the PCB file you need is on step 1. You'll need Cadsoft Eagle (www.cadsoft.de) to open, view and print it. Have you soldered surface mount parts before?
hey, i haven't done surface mount soldering before but i don't have to now because i was at a store and as i was looking around i found a science kit for something similar. so thanks for trying to help and mabye ill put up a picture or something.
Sure thing. Hmmm, perhaps you can hack your kit to do something extra!
Really nice project ! I didn't know about these propeller chips, look interesting.<br>But how do you generate audio out levels ? I can see P19 is connected to the audio amplifier but P19 is CMOS levels, no ? Or is there a DAC inside the propeller ? Or do you count on something like PWM ?
Yup, it's PWM. At 80 MHz, the propeller can generate a pretty smooth PWM output. It can even generate video!
Bless You. I am a fellow plant killer. I have a black thumb. Now I can go out and buy a plant (as soon as I make your Plant Whisperer) without planticid gilt. <br>Thank you so much,<br>From Black Thumb
Great! I plant to upgrade the firmware as I make improvements to the text-to-speech. Check back often!
Ha. Bad pun or typing error?
If you mean the planticid, it was a weak play on homicide of a plant. I am not sure if that is really a pun, but it was not a typing error.
Nope - it was in reference to jeff-o the author saying &quot;Great! I plant to upgrade &quot; <br>instead of &quot;Great! I plan to upgrade &quot; - plant instead of plan :)
Haha, awesome! I totally missed that, but I won't change it now (not that I can, without deleting the post).
Love the shape Jeff. Changing the silk of your name to a curve would totally complete it. Nice work!
Ooooh, finally I could own something that isn't cactus-like!
Perhaps some aloe, or a venus fly trap!
Or, dare I say it, an orchid!
Daring!<br><br>Actually, I saw a few nice ones at Lowe's when I was buying dirt. If I hadn't already bought the plant, I would have bought one of those.
Way too complicated for me to make, but this is really cool.
Not a beginner project, it's true. But thanks!

About This Instructable


68 favorites


Bio: By day, Jeff is the Jack of All Robots at Clearpath Robotics. By night, a mad scientist / hacker / artist / industrial designer wannabe!
More by jeff-o: Facet V1 Velomobile Simple Rock-Solid Cantilever Desk Polychromatic Harley Deluxe
Add instructable to: