Your Plants Can Take Care Of Themselves Now

One of [Sasa]’s life goals is to be able to sit back in his home and watch as robots perform all of his work for him. In order to work towards this goal, he has decided to start with some home automation which will take care of all of his house plants for him. This project is built from the ground up, too, and is the first part of a series of videos which will outline the construction of a complete, open-source plant care machine.

The first video starts with the sensors for the plants. [Sasa] decided to go with a completely custom module based on the STM32 microcontroller since commercial offerings had poor communications designs and other flaws. The small board is designed to be placed in the soil, and has sensors for soil moisture as well as other sensors for amount of light available and the ambient temperature. The improvements over the commercial modules include communication over I2C, allowing a large number of modules to communicate over a minimum of wires and be arranged in any way needed.

For this build everything is open-source and available on [Sasa]’s GitHub page, including PCB layouts and code for the microcontrollers. We’re looking forward to the rest of the videos where he plans to lay out the central unit for handling all of these sensors, and a custom dashboard for controlling them as well. Perhaps there will also be an option for adding a way to physically listen to the plants communicate their needs as well.

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Pocket-sized Device Sniffs Out Damp Masks

The realities of wearing a mask when you go out, from forgetting the thing in the car to dealing with fogged up glasses, have certainly taken some getting used to for most of us. But not every issue is immediately obvious. For example, experts say that as a mask gets damp from exhalation or perspiration it becomes less effective. Which is precisely why [Rick Pannen] has designed the Mask Moisture Meter.

As deep as we are into the Microcontroller Era, we really appreciate the simplicity of this design. It’s just a 555 timer, a buzzer, some LEDs, and a handful of passive components to get them all talking to each other. There’s no firmware or programming required; just put a fresh battery in the holder and away you go. The traces of the PCB serve as a moisture detector, so when the board is pushed against something wet enough, the red LED and buzzer will go off to warn the user.

Now admittedly, there’s a point where you certainly won’t need an electronic gizmo to tell you a mask is wet. But as [Rick] demonstrates in the video after the break, the circuit is sensitive enough to indicate when there’s moisture in the material that might not be immediately obvious to the eye.

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Coaxing Water From Desert Air

From the windtraps and stillsuits of Dune’s Arrakis, to the moisture vaporators of Tatooine, science fiction has invented fantastic ways to collect the water necessary for life on desert worlds. On Earth we generally have an easier go of it, but water supply in arid climates is still an important issue. Addressing this obstacle, a team of researchers from MIT and the University of California at Berkeley have developed a method to tease moisture out of thin air.

A year after the team first published their idea, they have successfully field-tested their method on an Arizona State University rooftop in Tempe, proving the concept and the potential for scaling up the technology. The device takes advantage of metal-organic framework(MOF) materials with high surface area that are able to trap moisture in air with as little as 10% humidity — even at sub-zero dewpoints. Dispensing with the need for power-hungry refrigeration techniques to condense moisture, this technique instead relies on the heat of the sun — although low-grade heat sources are also a possibility.

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An Indoor Garden? That’s Arduino-licious

Gardening is a rewarding endeavour, and easily automated for the maker with a green thumb. With simplicity at its focus,  Hackaday.io user [MEGA DAS] has whipped up a automated planter to provide the things plants crave: water, air, and light.

[MEGA DAS] is using a TE215 moisture sensor to keep an eye on how thirsty the plant may be, a DHT11 temperature and humidity sensor to check the airflow around the plant, and a BH1750FVI light sensor for its obvious purpose. To deliver on these needs, a 12V DC water pump and a small reservoir will keep things right as rain, a pair of 12V DC fans mimic a gentle breeze, and a row of white LEDs supplement natural light when required.

The custom board is an Arduino Nano platform, with an ESP01 to enable WiFi capacity and a Bluetooth module to monitor the plant’s status while at home or away. Voltage regulators, MOSFETs, resistors, capacitors, fuses — can’t be too careful — screw header connectors, and a few other assorted parts round out the circuit. The planter is made of laser cut pieces with plenty of space to mount the various components and hide away the rest. You can check out [MEGA DAS]’ tutorial video after the break!

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Sensing Soil Moisture: You’re Doing It Wrong!

If you compulsively search online for inexpensive microcontroller add-ons, you will see soil moisture measurement kits. [aka] built a greenhouse with a host of hacked hardware including lights and automatic watering. What caught our attention among all these was Step 5 in their instructions where [aka] explains why the cheap soil sensing probes aren’t worth their weight in potting soil. Even worse, they may leave vacationers with a mistaken sense of security over their unattended plants.

The sensing stakes, which come with a small amplifier, work splendidly out of the box, but if you recall, passing current through electrodes via moisture is the recipe for electrolysis and that has a pretty profound effect on metal. [Aka] shows us the effects of electrolysis on these probes and mentions that damaged probes will cease to give useful information which could lead to overworked pumps and flooded helpless plants.

There is an easy solution. Graphite probes are inexpensive to make yourself. Simply harvest them from pencils or buy woodless pencils from the art store. Add some wires and hold them with shrink tube, and you have probes which won’t fail you or your plants.

Here’s some garden automation if this only whet your whistle, and here’s a robotic friend who takes care of the weeds for you.

Using Backscatter Radio For A Soil Sensor Network

With almost 8 billion souls to feed and a changing climate to deal with, there’s never been a better time to field a meaningful “Internet of Agriculture.” But the expansive fields that make industrial-scale agriculture feasible work against the deployment of sensors and actuators because of a lack of infrastructure to power and connect everything. So a low-power radio network for soil moisture sensors is certainly a welcome development.

We can think of a lot of ways that sensors could be powered in the field. Solar comes to mind, since good exposure to the sun is usually a prerequisite for any cropland. But in practice, solar has issues, the prime one being that the plants need the sun more, and will quickly shade out low-profile soil-based sensors.

That’s why [Spyros Daskalakis] eschewed PV for his capacitive soil moisture sensors in favor of a backscatter technique very similar to that used in both the Great Seal Bug and mundane RFID tags alike. The soil sensor switches half of an etched PCB bowtie antenna in and out of a circuit at a frequency proportional to soil moisture. A carrier signal from a separate transmitter is reflected off the alternately loaded and unloaded antenna, picking up subcarriers with a frequency proportional to soil moisture. [Spyros] explains more about the sensor design and his technique for handling multiple sensors in his paper.

We really like the principles [Spyros] leveraged here, and the simplicity of the system. We can’t help but wonder what sort of synergies there are between this project and the 2015 Hackaday Prize-winning Vinduino project.

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Fully Automated Watering Robot Takes A Big Leap Forward Toward Greenhouse Automation

aquarius_robot

Greenhouse owners might find [David Dorhout]’s latest invention a groundbreaking green revolution! [David]’s Aquarius robot automates the laborious process of precision watering 90,000 square feet of potted plants. Imagine a recliner sized Roomba with a 30 gallon water tank autonomously roaming around your greenhouse performing 24×7 watering chores with absolute perfection. The Aquarius robot can do it all with three easy setups; add lines up and down the aisles on the floor for the robot to follow, set its dial to the size of your pots and maybe add a few soil moisture sensors if you want the perfect amount of water dispensed in each pot. The options include adding soil moisture sensors only between different sized plants letting Aquarius repeat the dispensing level required by the first plant’s moisture sensor for a given series.

After also digging through a pair of forum posts we learned that the bot is controlled by two Parallax propeller chips and has enough autonomous coding to open and close doors, find charging stations, fill its 30 gal water tank when low, and remember exactly where it left off between pit stops. We think dialing in the pot size could easily be eliminated using RFID pot identification tags similar in fashion to the Science Fair Sorting Project. Adjusting for plant and pot size as well as location might easily be automated using a vision system such as the featured Pixy a few weeks back. Finally, here are some featured hardware hacks for soil moisture sensing that could be incorporated into Aquarius to help remotely monitor and attend to just the plants that need attention: [Andy’s] Garden sensors, [Clover’s] Moisture control for a DIY greenhouse, [Ken_S’s] GardenMon(itoring project)

[David Dorhout] has 14 years experience in the agriculture and biotech industry. He has a unique talent applying his mad scientist technology to save the future of mankind as seen with his earlier Prospero robot farmer. You can learn more about Aquarius’s features on Dorhout R&D website or watch the video embedded below.

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