All-In-One Automated Plant Care

Caring for a few plants, or even an entire farm, can be quite a rewarding experience. Watching something grow under and then (optionally) produce food is a great hobby or career, but it can end up being complicated. Thanks to modern technology we can get a considerable amount of help growing plants, even if it’s just one plant in a single pot.

Plant Bot from [YJ] takes what would normally be a wide array of sensors and controllers and combines them all into a single device. To start, there is a moisture sensor integrated into the housing so that when the entire device is placed in soil it’s instantly ready to gather moisture data. Plant Bot also has the capability to control LED lighting if the plant is indoors.¬† It can control the water supply to the plant, and it can also communicate information over WiFi or Bluetooth.

The entire build is based around an ESP32 which is integrated into the PCB along with all of the other sensors and components needed to monitor a single plant. Plant Bot is an excellent all-in-one solution for caring for a plant automatically. If you need to take care of more than one at a time take a look at this fully automated hydroponic mini-farm.

Occam’s Razor: Gardening Edition

While the impulse to solving problems in complex systems is often to grab a microcontroller and some sensors to automate the problem away, interfacing with the real world is often a lot more difficult than it appears. Measuring soil moisture, for example, seems like it would be an easy way of ensuring plants get the proper amount of water, but soil is a challenging environment for electronics and this solution often causes more problems than it solves. [Kevin] noticed this problem with soil moisture sensors and set about solving this problem with a much simpler, though indirect, method of monitoring his plants electronically.

Rather than relying on soil conductivity for testing soil moisture levels, he has developed an alternate method of determining if the plants need to be watered simply by continuously weighing them. The hypothesis that he had was that a plant that needs water will weigh less as the available water respirates out of the plant or evaporates from the soil. This means that using a reliable sensor like a load cell to measure weight rather than an unreliable one like a soil moisture sensor will result in more reliable data he can use to automate his plants’ watering.

[Kevin]’s build is based around an ESP32 and a commercially-available load cell which are all built into the base of the plant’s pot. The design hides all of the electronics in a pleasant enclosure and is able to communicate relevant info wirelessly as well. The real story here, however, isn’t a novel use of an ESP32 chip, but rather out-of-the-box problem solving by using an atypical sensor to solve this problem. That’s not to say that you can’t ever use other sensors to directly monitor your garden and automate its health, though.

Check Soil Moisture At A Glance With This Useful Display

Keeping soil moist is key to keeping most plants happy. It can be a pain having to dip one’s fingers into dirty soil on the regular, so it’s desirable to have a tool to do the job instead. [Andrew Lamchenko] built a capable soil moisture monitor, and equipped it with an E-ink display for easy readings at a glance.

The device is built around the NRF52810 or other related NRF52 microcontrollers, which run the show. Rather than using an off-the-shelf sensor to determine soil conditions, an LMC555CMX timer chip is used, a variant of the classic 555 timer designed for low power consumption. Combined with the right PCB design, this can act as a moisture sensor by detecting capacitance changes in the soil. The sensor is also able to send data using the MySensor protocol, allowing it to be used as a part of a home automation system.

The soil is tested periodically with the moisture sensor, and displayed on the attached e-ink screen. Since the e-ink display requires no electricity except when rewriting the display, this allows the sensor to operate for long periods without using a lot of battery power. The soil can be checked, the display updated, and then the entire system can be put to sleep, using tiny amounts of power until it’s time to test the soil again.

It’s a great example of design for low power applications, where component selection really is everything. We’ve featured [Andrew]’s projects before; he’s long been a fan of using e-ink displays to create long-lasting, low power budget sensor platforms. Video after the break.

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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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