LED Matrix Hourglass Knows Which Way Is Up

October 8, 2021 by Donald Papp 6 Comments

[Fearless Night]’s slick dual hourglass doesn’t just simulate sand with LEDs, it also emulates the effects of gravity on those simulated particles and offers a few different mode options.

The unit uses an Arduino (with ATMEGA328P) and an MPU-6050 accelerometer breakout board to sense orientation and movement, and the rest is just a matter of software. Both the Arduino and the MPU-6050 board are readily available and not particularly expensive, and the LED matrix displays are just 8×8 arrays of red/green LEDs, each driven by a HT16K33 LED controller IC.

The enclosure and stand are both 3D-printed, and a PCB not only mounts the components but also serves as a top cover, with the silkscreen layer of the PCB making for some handy labels. It’s a clever way to make the PCB pull double-duty, which is a technique [Fearless Night] also used on their earlier optical theremin design.

Those looking to make one of their own will find all the design files and source code handily available from the project page. It might not be able to tell time in the classical sense, but seeing the hourglass displays react to the device’s orientation is a really neat effect.

LED Hourglass Moves Like The Real Thing

January 27, 2021 by Kristina Panos 6 Comments

If you want to waste time in a meaningful way, get yourself an hourglass. It’s simultaneously mesmerizing and terrifying to sit there and watch the seconds slip through the threshold that separates possibility from missed opportunity.

[Ty and Gig]’s LED hourglass is equally beautiful to watch. It doesn’t actually tell time, but that’s perfectly fine by us. What it does do is animate the LEDs to approximate grains of sand in gravity, no matter how the hourglass is tilted.

In either vertical orientation, the sand falls as long as there is some in the top. When the hourglass is horizontal, the LEDs settle just like real sand does. [Ty and Gig] achieved this with a whole lot of code that breaks the animation frames into structure arrays.

By contrast, the hardware part of this build is fairly simple: all that’s needed to replicate this build is some RGB LEDs a beefy power supply to drive them, an accelerometer, and a microcontroller.

[Ty and Gig] were planning to use an ESP8266, but misplaced it and went with an Arduino Mega instead. (You know what they say — buy a replacement and the one you lost will turn up almost immediately.) The beautiful frame is made from leftover purpleheart, a hardwood that turns purple with exposure to air. Check out the build video after the break.

Too lazy to reset your hourglass every hour? Here’s one that flips itself.

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Sit Up Straight!: Open Source Bluetooth Posture Sensing

December 16, 2020 by Danie Conradie 4 Comments

As more and more people spend their working hours behind a computer, bad posture and the accompanying back pain and back problems become a growing epidemic. To combat this in his own daily life, [ImageryEel] made PosturePack, a wearable Bluetooth-enabled posture sensor.

The PosturePack is designed to fit into a small pocket sewn into the pack of an undershirt, between the shoulder blades. It consists of a custom PCB with an ATmega32U4, BNO055 IMU, Bluetooth module, small LiPo and power circuitry. Based on the orientation data from the IMU, a notification is sent over Bluetooth to a smartphone whenever the user hunches forward.

[ImageryEel] says although the mobile notifications worked, haptic feedback integrated into the unit would be a better option. This could also be used to remind the user to stand up and take a break now and then, and provide an alternative to a smartwatch for activity monitoring without sending every movement to someone else’s servers. Software will always be the hardest part for projects like these, especially as the device become “smarter”. Learning to recognize activity and postures is actually a good place for tiny machine learning models.

Compared The posture sensors we covered before had to be installed and set up at a specific workstation, like an ultrasound-based version attached to a chair, and a webcam-based version.

A Beeping Toy Helps A Blind Dog Play Fetch

December 12, 2020 by Kristina Panos 9 Comments

When a beloved pet goes blind, it doesn’t mean they can’t or don’t want to play fetch anymore, only that the game must change a bit. [Bud Bennett]’s dog Lucy has slowly lost her sight to progressive renal atrophy but is still up for playing with toys, so [Bud] decided to make a beeper that can go inside various stuffed toys to help Lucy locate them. Lucy doesn’t care for commercial toys that chime constantly, especially once she’s got it in her mouth.

This tiny package is centered around an LIS3DH accelerometer and programmed with a PIC16F18313. When the toy is thrown up in the air, the accelerometer determines that it’s in free fall and triggers an interrupt on the PIC. The piezo buzzer starts beeping so Lucy can find it, then stops a short while later and waits for the next free fall. The power dissipation is so low that [Bud] expects to charge the 120 mAh LiPo battery about once a year.

We bet that communication between [Bud] and Lucy is already pretty good, but maybe she could be more expressive with a doggy soundboard.

Dad Scores Big With DIY Indoor Hockey Game

November 7, 2020 by Kristina Panos No comments

We suppose it’s a bit early to call it just yet, but we definitely have a solid contender for Father of the Year. [DIY_Maxwell] made a light-up hockey game for his young son that looks like fun for all ages. Whenever the puck is hit with the accompanying DIY hockey stick (or anything else), it lights up and produces different sounds based on its acceleration.

Inside the printed puck is an Arduino Nano running an MPU6050 accelerometer, a 12-NeoPixel ring, and a piezo buzzer. [DIY_Maxell] reused a power bank charging circuit to charge up the small LiPo battery.

The original circuit used a pair of coin cells, but the Arduino was randomly freezing up, probably because of the LEDs’ current draw. Be sure to check out the video after the break, which begins with a little stop motion and features a solder stand in the shape of a 3D printer.

Got a house full of carpet or breakables? You could always build an air hockey table instead.

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Peripheral Doesn’t Need Deskspace

September 11, 2020 by Brian McEvoy 9 Comments

Some of us are suckers for new hardware. There’s absolutely nothing shameful about a drawer overflowing with gamepads, roll-up keyboards, and those funny-shaped ergonomic mice. MyTeleTouch won’t sate your itch for new hardware because [Dimitar Danailov] didn’t design hardware you hold, because it uses your phone as a catch-all Human Interface Device, HID. A dongle plugs into a standard USB port, and your Android phone can emulate a USB keyboard, mouse, or gamepad over Bluetooth.

Chances are high that you already set up your primary computer with your favorite hardware, but we think we’ve found a practical slant for a minimalist accessory. Remember the last time you booted an obsolete Windows desktop and dug out an old mouse with a questionable USB plug? How long have you poked around the bottom of a moving box trying to find a proprietary wireless keyboard dongle, when you just wanted to type a password on your smart TV? What about RetroPi and a game controller? MyTeleTouch isn’t going to transform your daily experience, but it’ll be there when you don’t want to carry a full-size keyboard down three flights of stairs to press {ENTER} on a machine that spontaneously forgot it has a touch screen. If you don’t have opportunities to play the hero very often, you can choose to play the villain. Hide this in a coworker’s USB port, and while they think you’re sending a text message, you could be fiddling with their cursor.

We enjoy a good prank that everyone can laugh off, and we love little keyboards and this one raises the (space) bar.

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Bike Computer Powers On Long After Your Legs Give Out

August 20, 2020 by Brian McEvoy 13 Comments

A typical bicycle computer from the store rack will show your speed, trip distance, odometer, and maybe the time. We can derive all this data from a magnet sensor and a clock, but we live in a world with all kinds of sensors at our disposal. [Matias N.] has the drive to put some of them into a tidy yet competent bike computer that has a compass, temperature, and barometric pressure.

The brains are an STM32L476 low-power controller, and there is a Sharp Memory LCD display as it is a nice compromise between fast refresh rate and low power. E-paper would be a nice choice for outdoor readability (and obviously low power as well) but nothing worse than a laggy speedometer or compass.

In a show of self-restraint, he didn’t try to replace his mobile phone, so there is no GPS, WiFi, or streaming music. Unlike his trusty phone, you measure the battery life in weeks, plural. He implemented EEPROM memory for persistent data through power cycles, and the water-resistant board includes a battery charging circuit for easy topping off between rides.

When you toss the power of a mobile phone at a bike computer, someone will unveil the Android or you can measure a different kind of power from your pedals.

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