Around the Hackaday bunker, any plant other than a cactus has a real chance of expiring due to thirst. Perhaps we should build some of [MakersFunDuck]’s Moisture Duck boards. As you can see in the video below, the simple PCB with an ATtiny13A tells you when it is time to water the plants. The video also covers several exotic methods of determining the watering status, some of which are pretty complex.
The board is simple because the operation of the device is simple. A fixed resistor creates a voltage divider with the soil, and dry soil has higher resistance than moist soil. A pot sets a threshold, and the microcontroller measures the voltages.
Of course, if you can’t remember to water the plants, you probably can’t remember to change batteries either. So the device sleeps most of the time, and only wakes up every eight seconds to conserve battery. It would be nice to alarm on a low battery, and, honestly, we would probably have made the sleep time longer.
The video covers how he minimizes corrosion, but we aren’t sure how well the board will survive in damp soil, but with a little protection, it might last a while. Besides that, you could probably just consider them almost disposable.
The build starts with a 3D design drawn up in Fusion 360. The parts are then 3D printed, with opaque filament used for the handle and translucent PLA filament for the “blade”. Inside the blade elements are twenty WS2812B LEDs, creating the characteristic glow that made the Energy Sword so tantalizing to find in game. An ATtiny85 is charged with running the LEDs, with the aid of an IP5306 chip to act as a boost converter for the lithium-ion battery supplying the juice.
The work-from-home revolution enabled many workers to break free from the shackles of the office. Some employers didn’t like the loss of perceived control though, and saddled workers with all kinds of odious spyware to monitor their computer activity. Often, this involves monitoring mouse movement to determine if workers are slacking off or not. Mouse jigglers aim to fool these systems, and the MAUS from [MAKERSUN99] is one you can build yourself.
The MAUS is not a mechanical system that moves a real-life mouse on your desk. Instead, it directly injects emulated mouse movements via USB. It runs on an ATtiny85, which is able to spit out USB HID commands with the help of the V-USB software USB implementation. Along with the microcontroller, MAUS also features a red LED and a WS2812B RGB LED for user feedback. It’s also available on Tindie if your boss has you so busy that you don’t have time to build one.
It might not seem too impressive these days, but when microcontrollers with hardware USB support were more expensive and rare, the VUSB library was often used to create USB devices with an ATtiny85. It became so popular that the ATtiny85 even got packaged into USB dongle formfactors, like the DigiSpark boards. Well, you might not know this, but your Android smartphones can also work with USB mice and touchscreens in lieu of the built-in touchscreen display. [ErfanSn] combined these two ideas, creating a library to automate smartphone touchscreen events and keyboard input with an ATtiny85 — open for all of us to use, and with examples to spare.
The library is called DigiCombo, and it comes with plenty of examples for any screen touch event emulation that you might want. For instance, check out the README — it has video examples for Instagram page scrolling, unlock screen brute-forcing with random coordinates, playing the Stack rhythm game, and pinch zoom — all the building blocks for your smartphone touch emulation needs are covered pretty well! Of course, all of these have example code corresponding to them, that you can download and base your own ideas on. What’s more, the library is available in current Arduino IDE under the DigiCombo name. So if you need to, say, make a quick autoclicker for your phone, the library is a few steps away!
If your smartphone project was stalled because you needed to emulate touchscreen input, this library is your chance to get it done! We appreciate projects that let us get more from smartphones — there’s a lot of those laying around, they’re pretty functional and self-sufficient devices, so it makes sense that some projects of ours could do with a phone instead of a Raspberry Pi. Some manufacturers let us get a bit more of our phones, but this hasn’t really caught on, which means we have to make do with help of libraries like these. Or, perhaps, you rely on your phone day-to-day, and you’d like to add a touchpad to its back?
There’s no better way to introduce yourself than handing over a blinky PCB business card and challenging the recipient to a game of Connect Four. And if [Dennis Kaandorp] turns up early for a meeting, he can keep himself busy playing the ever popular game of Snake on his PCB business card.
Quite wisely, [Dennis] kept his design simple, and avoided the temptation of feature creep. His requirements were to create a minimalist, credit card sized design, with his contact details printed on the silk legend, and some blinky LED’s.
The tallest component on such a design is usually the battery holder, and he could not find one that was low-profile and cheap. Drawing inspiration from The Art of Blinky Business Cards, he used the 0.8 mm thin PCB itself as the battery holder by means of flexible arms.
Connect-Four is a two player game similar to tic-tac-toe, but played on a grid seven columns across and six rows high. This meant using 42 dual-colour LED’s, which would require a large number of GPIO pins on the micro-controller. Using a clever combination of matrix and charlieplexing techniques, he was able to reduce the GPIO count down to 13 pins, while still managing to keep the track layout simple.
It also took him some extra effort to locate dual colour, red / green LED’s with a sufficiently low forward voltage drop that could work off the reduced output resulting from the use of charlieplexing. At the heart of the business card is an ATtiny1616 micro-controller that offers enough GPIO pins for the LED matrix as well as the four push button switches.
His first batch of prototypes have given him a good insight on the pricing and revealed several deficiencies that he can improve upon the next time around. [Dennis] has shared KiCad schematic and PCB layout files for anyone looking to get inspired to design their own PCB business cards.
As [Phil Greenland] explains in the first part of his excellent write-up, the lithium battery used to keep the real-time clock (RTC) going on the Macintosh SE/30 has a nasty habit of exploding and leaking its corrosive innards all over the board. Looking to both repair the damage on a system that’s already had a battery popped and avoid the issue altogether on pristine boards, he started researching how he could replace the battery with something a bit more modern.
It turns out, the ATtiny85 is pin-compatible with the Mac’s original RTC chip, and indeed, [Andrew Makousky] had already written some code that would allow the microcontroller to emulate it. This is actually a bit more complex than you might realize, as the original RTC chip was doing double-duty: it also held 256 bytes of parameter random access memory (PRAM), which is where the machine stored assorted bits of info like which drive to boot from and the mouse cursor speed.
We aren’t saying that appliances are a scam, but we have noticed that when your appliances fail, there’s a good chance it will be some part you can no longer get from the appliance maker. Or in some cases, it’s a garden-variety part that should cost $2, but has been marked up to $40. When [Balakrishnan] had a failure of the timer control board for a Whirlpool washing machine, it was time to reverse engineer the board and replace it with a small microcontroller.
Of course, this kind of hack is one of those that won’t help you unless you need exactly that timer board. However, the process is generally applicable. Luckily, the motherboard chip was documented and the timer control board used a simple ATmega88, so it was easy to see that the devices were communicating via I2C.
Reading the I2C bus is easy with a logic analyzer, and this revealed the faulty device’s I2C address. The board that failed was only for display, so a simple program that does nothing other than accept I2C data put the washer in working order. Once it was working with an Arduino, an ATTiny45 did the work with a lot less space and cost.