Shower Occupancy Sensor Keeps Peace/Eliminates Odor At The Office

When the first two prototype ingredients listed are paperclips and Post-it notes you know it’s going to be good. The problem: one shower stall at work with numerous co-workers who bike to the office. The solution: a occupancy monitor that is smart enough to know that someone is actually in the room. You know what we’re talking about, a sensor that knows more than whether the door is open or closed. [James] got wise and built a sensor to monitor whether the door is bolted or not. We think this method is far superior to motion-based systems.

This uber-smart sensor is simply a pair of paperclips anchored on a rolled Post-it note substrate and shoved in the receiver on the door jamb. When the bolt is locked from the inside it pushes the paperclips together completing the simple circuit. This is monitored by a Spark Core but will work with just about any monitoring system you can devise. What we’re trying to figure out is how to ruggedize the paper-clip hack which we can’t think will perform well for very long. It looks like there’s room to bore out a bit more inside the receiver hole. Perhaps leaf switch with a 3D printed mounting bracket?

Oh, and kudos on the Ikea food storage container for the enclosure. That’s one of our favorite tricks for hacks which are installed for the long-run.

Holiday Cheer From The ATtiny13

There are smaller microcontrollers than the ATtiny13. Some ARM chips will fit on the head of a large pin, and even in Atmel world, the ATtiny10 comes in a tiny SOT-23-6 package – a size normally reserved for surface mount transistors. The ‘tiny13, though, can be programmed with just about any ISP and comes in an 8-pin DIP. It’s the bare minimum if you’re looking to break out of the world of Arduino, and you can do some pretty cool things with it, like playing some holiday audio with an SPI Flash chip.

[Vinod] tried opening up a cheap camera pen, but in the course of disassembly a few traces broke. He was now left with a 4Mbit SPI Flash chip. This was obviously the time to investigate what could be done with a small microcontroller and a huge amount of Flash. and the Attiny13 audio player was born.

The circuit uses one PWM for audio out, and reads audio directly from the Flash chip. The UART on board the ‘tiny13 is used to update the Flash, and there’s also a switch to select between play and record. If you’re counting, that means there are 4 pins for the Flash, 2 pins for the UART, 1 for the switch, one for the audio output, and the power and ground rails, all in an 8-pin package. That’s a pretty cool way to use one pin for two different functions.

You can check out a video of the project in action below.

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The Ultimate Tool Cart

[Burning Becks] set out on a quest to build the ultimate tool cart for himself, and we have to admit, what he’s come up with is pretty damn cool. Not only is the cart super organized and functional, it has an integrated fingerprint scanner to unlock one door, a keypad to unlock another drawer, an RFid tag to unlock another… and an RF remote too. Excessive? Perhaps. But hey, what if you accidentally burn off all your finger prints while building a hotplate SMD reflow oven? It’s possible!

To build the ultimate tool cart, [Becks] had to do some research. Specifically research right here at Hackaday, since we love covering unique work benches and tool boxes. He’s taken a few ideas from some of our favorite work space hacks like the computer tower toolbox, a cyclist’s bicycle workshop (yes it’s actually mounted on the bicycle!), a travelling electronics lab, and of course the mobile soldering workstation that sets up quickly and lets you get to work fast.

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3D Printable LED Diffusors

While you can get an LED matrix in any size or shape, the really cool looking ones that are perfect for low-res displays all have diffusors. When they come from a nameless Chinese factory, these diffusors are thin sheets of plastic set into an extruded plastic frame. Since [Jan] has a 3D printer, he figured a custom diffusor was just a few bits of filament and a SCAD file away.

The basis for this custom LED diffusor was a LoL Shield given to [Jan] by the creator at the recent 31C3 conference. This shield is really only just 126 LEDs, multiplexed and in an Arduino form factor, and that many LEDs were just too bright and indistinct next to each other. The plan for a 3D printed diffusor was hatched.

After taking a few measurements, a pair of OpenSCAD files were whipped up and printed out. Assembly consisted of pressing 126 tiny little white diffusors into a frame, but once everything was attached to the matrix, the results were worth it.

Check out the video below for the before and after, demonstrating what a few bits of plastic can do to a LED matrix.

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Hacklet 28 – Programmable Logic Hacks

FPGAs, CPLDs, PALs, and GALs, Oh My! This week’s Hacklet focuses on some of the best Programmable Logic projects on! Programmable logic devices tend to have a steep learning curve.  Not only is a new hacker learning complex parts, but there are entire new languages to learn – like VHDL or Verilog. Taking the plunge and jumping in to programmable logic is well worth it though. High-speed projects which would be impossible with microcontrollers are suddenly within reach!

fpga-hdmiA great example of this is [Tom McLeod’s] Cheap FPGA-based HDMI Experimenting Board. [Tom’s] goal was to create a board which could output 720p video via HDMI at a reasonable frame rate. He’s using a Xilinx Spartan 6 chip to do it, along with a handful of support components. The images will be stored on an SD card. [Tom] is hoping to do some video with the setup as well, but he has yet to see if the chip will be fast enough to handle video decoding while generating the HDMI data stream. [Tom] has been quiet on this project for a few months – so we’re hoping that either he will see this post and send an update, or that someone will pick up his source files and continue the project!

ardufpgaNext up is our own [technolomaniac] with his Arduino-Compatible FPGA Shield. Starting out with FPGAs can be difficult. [Technolomaniac] has made it a bit easier with this shield. Originally started as a project on .io and now available in The Hackaday Store, the shield features a Xilinx Spartan 6 FPGA. [Technolomaniac] made power and interfacing easy by including regulators and level shifters to keep the sensitive FPGA happy. Not sure where to start? Check out [Mike Szczys’] Spartan-6 FPGA Hello World! [Mike] takes us from installing Xilinx’s free tool chain to getting a “hello world” led blinker running!

lander3Still interested in learning about Programmable Logic, but not sure where to go? Check out [Bruce Land’s] Teaching FPGA parallel computing. Actually, check out everything [Bruce] has done on – the man is a living legend, and a wealth of information on electronics and embedded systems. Being a professor of engineering at New York’s Cornell University doesn’t hurt either! In Teaching FPGA parallel computing, [Bruce] links to Cornell’s ECE 5760 class, which he instructs. The class uses an Altera/Terasic DE2 FPGA board to demonstrate parallel computing using programmable logic devices. Note that [Bruce] teaches this class using Verilog, so all you seasoned VHDL folks still can learn something new!


chamFinally, we have [Michael A. Morris] with Chameleon. Chameleon is an Arduino compatible FPGA board with a Xilinx Spartan 3A FPGA on-board. [Michael] designed Chameleon for two major purposes:  soft-core processors, and intelligent serial communications interface. On the processor side Chameleon really shines. [Michael] has implemented a 6502 core in his design. This means that it would be right at home as the core of a retrocomputing project. [Michael] is still hard at work on Chameleon, he’s recently gotten fig-FORTH 1.0 running! Nice work [Michael]!

Want more programmable logic goodness? Check out our Programmable Logic List!

That about wraps things up for this episode of The Hacklet! As always, see you next week. Same hack time, same hack channel, bringing you the best of!

Prototyping With The ATMega1284P

While most people are moving onto ARMs and other high-spec microcontrollers, [Dave Cheney] is bucking the trend. Don’t worry, it’s for a good reason – he’s continuing work on one of those vintage CPU/microcontroller mashups that implement an entire vintage system in two chips.

While toying around with the project, he found the microcontroller he was using, the ATMega1284p, was actually pretty cool. It has eight times the RAM as the ever-popular 328p, and twice as much RAM as the ATMega2560p found in the Arduino Mega. With 128k of Flash, 4k of EEPROM, 32 IOs, and eight analog inputs, it really starts to look like the chip the Arduino should have been built around. Of course historical choices don’t matter, because [Dave] can just make his own 1284p prototyping board.

The board is laid out in Fritzing with just a few parts including a crystal, a few caps, an ISP connector, and pins for a serial connector. Not much, but that’s all you need for a prototyping board.

The bootloader is handled by [Maniacbug]’s Mighty 1284 Arduino Support Package. This only supports Arduino 1.0, not the newer 1.5 versions, but now [Dave] has a great little prototyping board that can be put together from perfboard and bare components in a few hours. It’s also a great tool to continue the development of [Dave]’s Apple I replica.

A Bluetooth Garage Door, Take Three

A few years ago, [Lou] came up with a pretty clever build to open his garage door with his phone. He simply took a Bluetooth headset, replaced the speaker with a transistor, and tied the transistor to a few wires coming out of his garage door opener. When the Bluetooth headset connected, the short beep coming from the speaker output opened the door.

The newest version of this build does away with the simple Bluetooth headset and replaces it with a Bluetooth 4.0 chip. The reason for this is that Apple and their walled garden of an App store would never allow a Samsung Bluetooth headset to be used with one of their iDevices.

The latest build is just about as simple as using a Bluetooth headset. A board that appears to use TI’s CC2540 chip is attached to the garage door opener with a few passives and a transistor. Pairing the new circuit with a phone is as simple as shorting a pair of pins, and the new iOS app does exactly what it should – opens a garage door at the press of a non-button.

While it’s not something that can be put together with scraps from a junk drawer, it’s still an extremely simple solution to opening a garage door with a phone. Video below.

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