Never Forget Your USB Stick Again

USB sticks are very handy. They are a very portable and relatively inexpensive means of storing data. Possibly the most annoying part about using one of these devices is when you inevitable leave it behind somewhere by accident. This is especially true if it contains sensitive information. [Eurekaguy] feels your pain, and he’s developed a solution to the problem.

[Eurekaguy] designed a custom cap for USB sticks that beeps approximately every minute after the USB stick has been plugged in for five minutes. The cap is 3D printed and then slightly modified with four 1mm holes. Two wires are routed between these holes to make contact points for the VCC and GND pins of the USB stick.

The beep circuit is comprised of a tiny PIC12F629 microcontroller along with a couple of other supporting components. The circuit is wired together dead bug style to conserve space. Three AG5 batteries power the circuit. A small piezo speaker provides the repeating beep to remind you to grab your USB stick before you walk away from the computer.

[Thanks Irish]

Boxing Trainer Uses DIY Force Sensors

A team of Cornell students have designed and built their own electronic boxing trainer system. The product of their work is a game similar to Whack-A-Mole. There are five square pads organized roughly into the shape of a human torso and head. Each pad will light up based on a pre-programmed pattern. When the pad lights up, it’s the player’s job to punch it! The game keeps track of the player’s accuracy as well as their reaction time.

The team was trying to keep their budget under $100, which meant that off the shelf components would be too costly. To remedy this, they designed their own force sensors. The sensors are basically a sandwich of a few different materials. In the center is a 10″ by 10″ square of ESD foam. Pressed against it is a 1/2″ thick sheet of insulating foam rubber. This foam rubber sheet has 1/4″ slits cut into it, resulting in something that looks like jail bars. Sandwiching these two pieces of foam is fine aluminum window screen. Copper wire is fixed the screen using conductive glue. Finally, the whole thing is sandwiched between flattened pieces of corrugated cardboard to protect the screen.

The sensors are mounted flat against a wall. When a user punches a sensor, it compresses. This compression causes the resistance between the two pieces of aluminum screen to change. The resistance can be measured to detect a hit. The students found that if the sensor is hit harder, more surface area becomes compressed. This results in a greater change in resistance and can then be measured as a more powerful hit. Unfortunately it would need to be calibrated depending on what is hitting the sensor, since the size of the hitter can throw off calibration.

Each sensor pad is surrounded by a strip of LEDs. The LEDs light up to indicate which pad the user is supposed to hit. Everything is controlled by an ATMEGA 1284p microcontroller. This is the latest in a string of student projects to come out of Cornell. Make sure to watch the demonstration video below. Continue reading “Boxing Trainer Uses DIY Force Sensors”

Scope Noob: Microcontroller Quirks with DDS

In this installment of Scope Noob I’m working with Direct Digital Synthesis using a microcontroller. I was pleasantly surprised by some of the quirks which I discovered during this process. Most notably, I had a chance to look at errant triggers solved by using holdoff and a few timing peculiarities introduced by my use of the microcontroller. Here’s a video synopsis but I’ll cover everything in-depth after the break.

Continue reading “Scope Noob: Microcontroller Quirks with DDS”

Solar Powered Circuit Waters Your Plants

 

If you want your plants to stay healthy, you need to make sure they stay watered. [Dimbit] decided to build his own solar powered circuit to help automatically keep his plants healthy. Like many things, there is more than one way to skin this cat. [Dimbit] had seen other similar projects before, but he wanted to make his smarter than the average watering project. He also wanted it to use very little energy.

[Dimbit] first tackled the power supply. He suspected he wouldn’t need much more than 5V for his project. He was able to build his own solar power supply by using four off-the-shelf solar garden lamps. These lamps each have their own low quality solar panel and AAA NiMH cell. [Dimbit] designed and 3D printed his own plastic stand to hold all of the solar cells in place. All of the cells and batteries are connected in series to increase the voltage.

Next [Dimbit] needed an electronically controllable water valve. He looked around but was unable to find anything readily available that would work with very little energy. He tried all different combinations of custom parts and off-the-shelf parts but just couldn’t make something with a perfect seal. The solution came from an unlikely source.

One day, when [Dimbit] ran out of laundry detergent, he noticed that the detergent bottle cap had a perfect hole that should be sealable with a steel ball bearing. He then designed his own electromagnet using a bolt, some magnet wire, and a custom 3D printed housing. This all fit together with the detergent cap to make a functional low power water valve.

The actual circuit runs on a Microchip PIC microcontroller. The system is designed to sleep for approximately nine minutes at a time. After the sleep cycle, it wakes up and tests a probe that sits in the soil. If the resistance is low enough, the PIC knows that the plants need water. It then opens the custom valve to release about two teaspoons of water from a gravity-fed system. After a few cycles, even very dry soil can reach the correct moisture level. Be sure to watch the video of the functioning system below. Continue reading “Solar Powered Circuit Waters Your Plants”

Using Router SoCs as WiFi Modules (Yet Again)

8-bit AVRs and 32-bit ARMs do one thing, and one thing well: controlling other electronics and sensors while sipping power. The Internet of Things is upon us and with that comes the need for connecting to WiFi networks. Already, a lot of chips are using repackaged System on Chips to provide an easy way to connect to WiFi, and the USR-WIFI232-T is the latest of the bunch. It’s yet another UART to WiFi bridge, and as [2XOD], it’s pretty easy to connect to an AVR.

The module in question can be had through the usual channels for about $11, shipped straight from China, and the only purpose of this device is to provide a bridge between a serial port and a wireless network. They’re not that powerful, and are only meant for simple tasks,

[2XOD] got his hands on one of these modules and tested them out. They’re actually somewhat interesting, with all the configuration happening over a webpage served from the device. Of course the standard AT commands are available for setting everything up, just like the ESP8266.

With a month of testing, [2XOD] has found this to be a very reliable device, logging temperatures every minute for two weeks. There’s also a breakout board available to make connection easy, and depending on what project you’re building, these could be a reasonable stand-in for some other popular UART -> WiFi chips.

The Hackaday Prize: Interview With A ChipWhisperer

chipwhisperer

Every finalist for The Hackaday Prize has some aspect of it that hasn’t been done before; finding the chemical composition of everything with some 3D printed parts is novel, as is building a global network of satellite ground stations with off the shelf components. [Colin]’s ChipWhisperer, though, has some scary and interesting implications. By looking inside a microcontroller as its running, the ChipWhisperer is able to verify – or break – security on these chips. It’s also extremely interesting and somewhat magical being able to figure out what data a chip is processing simply by looking at its power consumption.

We have no idea who the winner of The Hackaday Prize is yet, and I’m hoping to remain ignorant of that fact until the party two weeks from now. Until then, you can read the short interview with [Colin O’Flynn], or check out his five-minute video for the ChipWhisperer below:

Continue reading “The Hackaday Prize: Interview With A ChipWhisperer”

Digital Decade Resistance Box on the Cheap

[Stynus] has finished a unique decade resistance box which doesn’t use conventional rotary switches to select the appropriate resistors. These switches are old fashioned and expensive, so [Stynus] built this decade resistance box that uses a microcontroller and a series of relays to switch the resistors.

Simply selecting a resistance on the screen tells the microcontrollers which resistors need to be switched in order to provide the proper resistance. The box uses relays to do switching instead of transistors because the transistors don’t handle high frequency AC as well as the relays. The device is powered by an 18V transformer and rectifier and, as a bonus, [Stynus] got all of his parts on the cheap which made this a great solution to the expensive resistance decade box problem.

This is a very well-polished piece of test equipment. We’ve featured other decade resistance boxes but never one that was controlled by a microcontroller. All of the PCB layouts and the code for microcontroller are available on the project site if you have a desire to make your own.