DUO Portable: A Homebrew Computer With Keyboard And Display


[Jack] is famous ’round these parts for his modern reinterpretations of very early computers. He’s created a computer entirely out of logic chips, a microcontroller-powered multicore box, and even a very odd one-instruction computer. For his latest project, he’s stepped up his game and made something that’s actually fairly useful: a microcontroller-powered system with an integrated keyboard and display.

The DUO Portable, as [Jack] calls his new toy, is built around an ATMega1284P microcontroller. Also on this board is a serial EEPROM that acts as a very small drive, a 102×64 pixel graphic display, and enough tact switches to create a QWERTY keyboard.

The DUO Portable boots to a primitive operating system where files can be created, edited, and saved. The programming language for this computer  is called DCPL – the DUO Portable Command Language – and can be used to create anything from a simple ‘Hello World’ program to a block-building game.

Like all of [Jack]’s homebrew computer projects, he’s written an emulator that can be run in a browser. There’s also video of [Jack] playing around with the DUO Portable available below.

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Autonomous Lighting with Intelligence


Getting into home automation usually starts with lighting, like hacking your lights to automatically turn on when motion is detected, timer controls, or even tying everything into an app on your smart phone. [Ken] took things to a completely different level, by giving his lighting intelligence.

The system is called ‘Myra’, and it works by detecting what you’re doing in the room, and based on this, robotic lights will optimally adjust to the activity. For example, if you’re walking through the room, the system will attempt to illuminate your path as you walk. Other activities are detected as well, like reading a book, watching TV, or just standing still.

At the heart of the ‘Myra’ system is an RGBD Sensor (Microsoft Kinect/Asus Xtion). The space in the room is processed by a PC running an application to determine the current ‘activity’. Wireless robotic lights are strategically placed around the room; each with a 2-servo system and standalone Arduino. The PC sends out commands to each light with an angle for the two axis and the intensity of the light. The lights receive this command wirelessly via a 315MHz receiver, and the Arduino then ‘aims’ the beam according to the command.

This isn’t the first time we’ve seen [Ken’s] work; a couple of years ago we saw his extremely unique ‘real life’ weather display.  The ‘Myra’ system is still a work in progress, so we can’t wait to see how it all ends up.  Be sure to check out the video after the break for a demo of the system.

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ATMega & ATtiny Core Temperature Sensors


We don’t know if this will come as a surprise to the regular Hackaday reader, but a whole bunch of Atmel microcontrollers have a very cool feature hidden away in their datasheets. Most of them – everything from the ATMega 168, 328, 32u4, to the ATtiny85 and  84 have a temperature sensor right on the chip. [Connor] did a little bit of research on this sensor and came up with a little bit of code that spits out the core temperature of these Atmel chips over the serial port.

The temperature sensor on these Atmel chips is accessed by writing a code – ‘100111’ for the Mega32u4 and ‘100010’ for the tiny84, for example – into the ADMUX register on the chip. According to the datasheet, the returned temperature is accurate to +- 10°C, but that can be easily calibrated by holding an ice cube (in a plastic bag, of course) up to the chip.

With a little more code, [Connor] is able to output the temperature of the microcontroller core over a serial port. In testing, his chip started out at 20°C and reached equilibrium at 24°C after about a minute. Pretty neat, and could be used as a temperature sensor for a project in a pinch.

PVC Cryptex Keeps Your Stuff Safe


Apparently we’ve never shared a Cryptex before! Made popular (and coined) by the Da Vinci Code, a Cryptex is a combination style lock originally used to store secret messages. You can make your very own using a few pieces of PVC pipe, some epoxy, and nuts and bolts!

Cryptexes have a clever design that cannot really be lock picked, without simply breaking it. In [Dan Brown’s] novel, it was said that some Cryptexes stored a fragile vial of vinegar with the message written on papyrus — that way, if it was forcibly opened the vile would break, dissolving the thin papyrus note.

They work similar to a bicycle’s combination lock, where if the correct password is guessed, the tumblers inside align, allowing the two halves of the cylinder to come apart. It’s actually a very simple design on the inside, and the whole mechanism can easily be made by yourself with minimal tools.

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The K9 Curfew Door


[Kenbob] is an awesome pet owner. He has two small dogs that have free access to the backyard through a doggy door. It’s great during the day, but they have to close it at night to stop the dogs from bothering the neighbors. So he decided to make an automatic curfew based doggy door!

Before setting out on his project, he determined some design goals that had to be met. Namely, he couldn’t have it lock the dogs outside by accident! The hack makes use of an old large format flat-bed scanner that had stopped working a while ago. As it so happened, this scanner had just enough carriage travel to be able to actuate a cover for the doggy door. After reinforcing the sliding cover, he hooked it up to an Arduino Nano, a RTC and a H-Bridge motor driver in order to control it.

In order to add scheduling ability and to program the door remotely, he has also hooked it into his existing x10 control infrastructure in his house — not too shabby! It also features a manual 3-position switch to lock it open, closed, or to leave it on automatic. The question is, can a raccoon get in?

He’s been testing it for a few weeks and it works quite well, although he admits it is not the most rugged solution — lucky for him, his dogs aren’t the type to run headfirst into things. Stick around after the break to see it in action.

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Are We Not Indestructible? We Are Quiz Buttons!

In what we hope is a new trend in interviewing, some of the people at [Anthony]’s place of work asked him to make some wireless quiz buttons. He took the task quite seriously, making them extremely robust and low-power.

[Anthony] is experienced in the button arts, having made this party push button for a wedding reception. His design for the quiz buttons is a little different. Each button has an Arduino Pro mini and an nRF24L01 wireless RF module. On the receiver side is an Arduino Pro micro and an another RF module. A connected PC captures the serial data and  displays the pressed button’s ID. It also shows the order in which subsequent buttons were pressed and the time elapsed between them.

The really notable part of this build aside from the awesome laser-cut MDF Devo energy dome button housings is the extremely low power consumption of the transmitting Arduinos. [Anthony] has designed them to go into sleep mode which disables all on-board circuitry and only wakes on interrupt. He removed the power LED and the voltage regulator since they run on 2-AA batteries. The voltage regulator was drawing more than 25mA in sleep mode. Because of these mods, each button consumes < 1μA, which is less power than the batteries can self discharge over their lifetime.

[Thanks Jef]

Verifying A Wireless Protocol With RTLSDR


[Texane] is developing a system to monitor his garage door from his apartment. Being seven floors apart, running wires between the door and apartment wasn’t an option, so he turned to a wireless solution. Testing this wireless hardware in an apartment is no problem, but testing it in situ is a little more difficult. For that, he turned to software defined radio with an RTLSDR dongle.

The hardware for this project is based around a TI Stellaris board and a PTR8000 radio module. All the code for this project was written from scratch (Github here), making it questionable if the code worked on the first try. To test his code, [Texane] picked up one of those USB TV tuner dongles based around the RTL2832U chipset. This allowed him to monitor the frequencies around 433MHz for the packets his hardware should be sending.

After that, the only thing left to do was to write a frame decoder for his radio module. Luckily, the datasheet for the module made this task easy.

[Texane] has a frame decoder for the NRF905 radio module available in his Git. It’s not quite ready for serious applications, but for testing a simple radio link it’s more than enough.