A wooden robot with a large fresnel lens in a sunny garden

Gardening Robot Uses Sunlight To Incinerate Weeds

June 30, 2023 by Robin Kearey 36 Comments

Removing weeds is a chore few gardeners enjoy, as it typically involves long sessions of kneeling in the dirt and digging around for anything you don’t remember planting. Herbicides also work, but spraying poison all over your garden comes with its own problems. Luckily, there’s now a third option: [NathanBuildsDIY] designed and built a robot to help him get rid of unwanted plants without getting his hands dirty.

Constructed mostly from scrap pieces of wood and riding on a pair of old bicycle wheels, the robot has a pretty low-tech look to it. But it is in fact a very advanced piece of engineering that uses multiple sensors and actuators while running on a sophisticated software platform. The heart of the system is a Raspberry Pi, which drives a pair of DC motors to move the whole system along [Nathan]’s garden while scanning the ground below through a camera.

The Pi runs the camera’s pictures through a TensorFlow Lite model that can identify weeds. [Nathan] built this model himself by taking hundreds of pictures of his garden and manually sorting them into categories like “soil”, “plant” and “weed”. Once a weed has been detected, the robot proceeds to destroy it by concentrating sunlight onto it through a large Fresnel lens. The lens is mounted in a frame that can be moved in three dimensions through a set of servos. A movable lens cover turns the incinerator beam on or off.

Sunlight is focused onto the weed through a simple but clever two-step procedure. First, the rough position of the lens relative to the sun is adjusted with the help of a sun tracker made from four light sensors arranged around a cross-shaped cardboard structure. Then, the shadow cast by the lens cover onto the ground is observed by the Pi’s camera and the lens is focused by adjusting its position in such a way that the image formed by four holes in the lens cover ends up right on top of the target.

Once the focus is correct, the lens cover is removed and the weed is burned to a crisp by the concentrated sunlight. It’s pretty neat to see how well this works, although [Nathan] recommends you keep an eye on the robot while it’s working and don’t let it near any flammable materials. He describes the build process in full detail in his video (embedded below), hopefully enabling other gardeners to make their own, improved weed burner robots. Agricultural engineers have long been working on automatic weed removal, often using similar machine vision systems with various extermination methods like lasers or flamethrowers.

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A BASIC Interpreter For The Raspberry Pi Pico

June 28, 2023 by Lewin Day 38 Comments

It’s pretty easy to program the Raspberry Pi Pico in Python, or you can use C or C++ if you so desire. However, if you fancy the easy language of yesteryear, you might like PiccoloBASIC from [Gary Sims].

Putting it simply, piccoloBASIC is a BASIC interpreter that runs on the Raspberry Pi Pico. It features all the good bits of BASIC such as GOTO and GOSUB commands, that fancier languages kind of look down upon. It’s also got enough built-in routines to handle regular programming life, like sleeps, delays, a basic pseudorandom number source, trigonometric functions, and the ability to deal with floating point numbers. As far as microcontroller tasks go, it’s got rudimentary support for talking to GPIOs right now via the pinon and pinoff commands. However, it’s probably not the way to go if you want to bit-bang an SD card to within an inch of its speed rating.

Down the road, [Gary] hopes to add support for features like the Pico’s I2C, SPI, and PIO hardware, along with networking protocols and Bluetooth. PEEK and POKE are also hopefully on the way for those that like to fiddle with memory directly.

Meanwhile, if you’re looking for a different yet similar take, explore the port of MMBasic to the Pico platform. Video after the break.

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Networking With Balloons

June 26, 2023 by Bryan Cockfield 14 Comments

Starlink has been making tremendous progress towards providing world-wide access to broadband Internet access, but there are a number of downsides to satellite-based internet such as the cluttering of low-Earth orbit, high expense, and moodiness of CEO. There are some alternatives if standard Internet access isn’t available, and one of the more ambitious is providing Internet access by balloon. Project Loon is perhaps the most famous of these (although now defunct), but it’s also possible to skip the middleman and build your own high-altitude balloon capable of connection speeds of 500 Kbps.

[Stephen] has been working on this project for a few months and while it doesn’t support a full Internet connection, the downlink on the high altitude balloon is fast enough to send high-resolution images in near-real-time. This is thanks to a Raspberry Pi Zero on board the balloon that is paired with an STM32 board which handles the radio communication on a RF4463 transceiver module. The STM32 acts as an intermediary or buffer to ensure reliable information is sent out on the radio, rather than using the Pi directly. [Stephen] also wrote a large chunk of the software responsible for handling all of these interactions, optimized for balloon flight specifically.

The blog post for this project was written a few weeks ago with a reported first launch date for the system already passed, so we will eagerly anticipate the results and the images he was able to gather using this system. Eventually [Stephen] hopes the downlink will be fast enough for video as well.Balloons are an underappreciated tool as well, and this isn’t the only way that they can be used to help send radio signals from place to place.

Modular Keyboard And Custom Game Controller

June 20, 2023 by Bryan Cockfield 3 Comments

Most video games, whether on console or PC, have standardized around either a keyboard and mouse or an analog controller of some sort, with very little differences between various offerings from the likes of Sony, Microsoft, Nintendo, or even Valve. This will get most of us through almost all video games, but for those looking to take their gameplay up a notch or who are playing much more complex games, certain specialized controllers are available, but they might not meet everyone’s specific needs. Thanks to this custom, modular keyboard anyone should be able to make exactly the controller they need.

The device features a grid of 15 interfaces where modules like buttons, potentiometers, encoders, and joysticks can be placed. Each module can be customized to a significant extent on their own, and they can be placed anywhere on the grid. The modules themselves can be assigned to trigger keyboard presses or gamepad motions depending on the needs of the user. A Raspberry Pi handles the inputs and translates them to the computer, so in that regard it functions no differently than a standard keyboard or gamepad would. Programming is done by sending commands via a USB serial port, with the ability to save various configurations as well.

The modular controller is open-source in terms of hardware and software, with easy assembly using through-hole components and a customizable 3D printed cover for anyone looking to make their own. The project’s creator [Daniel] had flight simulators in mind when designing the device, which often benefit from having more specialized controllers, but any game with lots of specific inputs from Starcraft to League of Legends could benefit from a custom controller or keyboard like this. Flight simulators are more often the targets of specialized and unique controls, though, like this custom yoke or this physical control panel.

RetroPie, Without The Pi

June 6, 2023 by Bryan Cockfield 24 Comments

The smart television is an interesting idea in theory. Rather than having the cable or satellite company control all of the content, a small computer is included in the television itself to host and control various streaming clients and other services. Assuming you have control of the software running on the computer, and assuming it isn’t turned into a glorified targeted advertising machine, this can revolutionize the way televisions are used. It’s even possible to turn a standard television into a smart TV with various Android devices, and it turns out there’s a lot more you can do with these smart TV contraptions as well.

With most of these devices, a Linux environment is included running on top of an ARM platform. If that sounds similar to the Raspberry Pi, it turns out that a lot of these old Android TV sets are quite capable of doing almost everything that a Raspberry Pi can do, with the major exception of GPIO. That’s exactly what [Timax] is doing here, but he notes that one of the major hurdles is the vast variety of hardware configurations found on these devices. Essentially you’d have to order one and hope that you can find all the drivers and software to get into a usable Linux environment. But if you get lucky, these devices can be more powerful than a Pi and also be found for a much lower price.

He’s using one of these to run RetroPie, which actually turned out to be much easier than installing a more general-purpose Linux distribution and then running various emulation software piecemeal. It will take some configuration tinkering get everything working properly but with [Timax] providing this documentation it should be a lot easier to find compatible hardware and choose working software from the get-go. He also made some improvements on his hardware to improve cooling, but for older emulation this might not be strictly necessary. As he notes in his video, it’s a great way of making use of a piece of electronics which might otherwise be simply thrown out.

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Zelda Guardian Sculpture Tracks Humans And Pets Via Camera

June 3, 2023 by Lewin Day 3 Comments

In The Legend of Zelda: Breath of the Wild Guardians are a primitive form of sentry turret that tracks the player with a watchful eye. Inspired by this, [npentrel] decided to whip up one of her own in the real world.

The build relies on a Raspberry Pi kitted out with its usual camera for machine vision purposes. It uses the Viam robot toolkit, which runs a machine learning model to detect pets and humans on the camera feed. The guardian then tracks any pets or humans that show up by turning its head, and thus the camera, with a servo controlled by a PWM signal via the Raspberry Pi’s GPIO pins. It’s all wrapped up in a nicely-decorated 3D printed model that really does look like something straight out of Breath of the Wild.

Sentry projects are a great way to learn about electronics, mechanics, and image processing techniques. It’s funny to see how advanced and complicated these projects were fifteen years ago, compared to how easy they are today with modern machine learning libraries. How times change!

What Next For The SBC That Has Everything?

May 31, 2023 by Jenny List 113 Comments

In the decade-and-a-bit since the first Raspberry Pi was launched we’ve seen an explosion of affordable single-board computers (SBCs), but as the prices creep up alongside user expectation and bloat, [Christopher Barnatt] asks where the industry will go next.

The Pi started with an unbeatable offer, $35 got you something similar to the desktop PC you’d had a decade earlier — able to run a Linux desktop on your TV from an SD card. Over the years the boards have become faster and more numerous, but the prices for ARM boards are now only nominally as affordable as they were in 2012, and meanwhile the lower end of x86 computing is now firmly in the same space. He demonstrates how much slower the 2023 Raspberry Pi OS distribution is on an original Pi compared to one of the early pre-Raspbian distros, and identifies in that a gap forming between users. From that he sees those people wanting a desktop heading towards the x86 machines, and the bare-metal makers at the lower end heading for the more powerful microcontrollers which simply weren’t so available a decade ago.

We have to admit that we agree with him, as the days when a new Raspberry Pi board was a special step forward rather than just another fast SBC are now probably behind us. In that we think the Pi people are probably also looking beyond their flagship product, as the hugely successful lunches of the RP2040 and the industrial-focused Compute Module 4 have shown.

What do you think about the SBC market? Tell us in the comments.

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