Ditch that boring mouse for a military-grade trackball


The bad thing about this type of hack is that now [Tomek Dubrownik] needs to cut a hole in his desk to house the thing. He got this military grade trackball working over USB. It’s old, and could be used as a blunt weapon. But as the video shows it still makes a great input device.

He found the hardware on Allegro — a Polish auction site similar to eBay — for just $20. The original circuitry didn’t make a lot of sense, but a bit of probing with the old oscilloscope let him establish connections to the encoders which are read by some TI 54xx parts. Apparently they use the same logic as 7400 parts but are military grade. He chose a ATmega32u4 development board for his replacement control board. That chip has native USB support so the rest is just a matter of passing data like an HID input device. His code even lets him use those pushbuttons to toggle between cursor movement and window scrolling.

[Tomek] translated his post into English after some prompting by friends at the Warsaw Hackerspace. Here’s the original in Polish if you’re interested.

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AVR programmer made without a programmer

[blueHash] uses this cheap development board as an AVR programmer. What’s interesting to us is that it solves the chicken-or-egg problem that is usually encountered when bootstrapping a programmer. We’ve written about this issue before. Most programmers use microcontrollers, which first need to be flashed using a programmer. But it turns out the chip on this dev board has a DFU mode which gets around that conundrum.

He grabbed a uSD dev board for about $6. It’s got a crystal, an ATmega32u4 chip, and on the other side there’s a MicroSD card slot. We looked around and found an Atmel Datasheet (PDF) which describes the Device Firmware Upgrade mechanism. The AVR devices which support DFU are factory configured to use it. This dev board is designed to use DFU so all [blueHash] needed to do is find and configure a ISP firmware package that worked with this chip.

GPS dog collar keeps track of your walks

[Becky Stern] came up with a way to make sure you and your dog are getting enough exercise. It’s a dog collar mounted GPS that measures how far you have walked. Just set your target distance and the progress bar in the middle of this flower will let you know when you reached it.

The most obvious piece of hardware is the OLED board which is sticking out like a sore thumb. But if you’d like to be a little more discreet you could forego the full-featured display for some carefully places LEDs to make up a circular progress bar. The GPS module itself fits well in the center of the flower, which [Becky] shows us how to make out of wire-edged ribbon. Hidden on the other side is an ATmega23u4 breakout board running the Arduino bootloader.

If you’re interested in sewables and textiles [Becky] uses a lot of basic techniques that are good to learn. Check it out in the clip after the break. She’s always shown a remarkable ability to develop projects which won’t scare away the villagers in the way our wire-sprouting breadboard hacks sometimes do.

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Drop-in board for NES ROM chip makes cartridge reprogrammable

Here’s the guts from [Dext0rb's] Super Nintendo cartridge. It’s easy to pick out the dark-colored board which lets him reflash SNES ROMs via USB. We’ve seen this done a number of times, but this is a much cleaner option than hacks that just add a dead-bug-style memory chip.

The board he designed has a double-row of pin headers sized to fit the footprint vacated by the original ROM chip. The board has a mini-USB connector which can be accessed through a hole he cut in the side of the cartridge enclosure. This is in the right place so that you cannot plug it in when it’s being used in the SNES (which would cause damage). The ATmega32u4 chip handles USB connectivity and programs the 32 megabit flash chip which stores the ROM. He’s posted a few articles on the blog portion of his site which you’ll find interesting. We suggest starting with this hardware teaser.

A very detailed reflow oven build


If you do a lot of SMD soldering, a reflow oven is the fastest and most efficient way to get all those tiny components attached to your PCB. [Frank Zhao] saw the reflow ovens we featured here over the last few weeks and figured he might as well show off his rig as well. We’re certainly glad he did, because his very thorough writeup is a great stepping stone for anyone looking to construct a reflow oven of their own.

Like many others, he started off with a used toaster oven, modifying it to be controlled directly via the power cable rather than the oven’s dials. He built a small PCB to regulate the oven, which features an ATmega32u4 and thermocouple to keep the temperature in check. Control of the heating element is done using a solid state relay, for which he built his own heatsink.

He studied the reflow profile of the solder he would be using, programming the microcontroller to regulate the heating/cooling process without requiring any user input, aside from turning the oven on.

Check out the video below to see a brief overview of his system, and be sure to swing by his writeup to take a look at all the build details. There are a handful of additional videos along with plenty of pictures there, walking through each step of the process.

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Do you know what you’re doing when integrating PC-side apps with USB microcontrollers?

The advent of integrated USB peripherals in microprocessors (PIC, AVR, etc.) has certainly taken a lot of the work out of developing USB devices, not to mention reducing the silicon parts in these designs. But do you know what you’re doing when it comes to controlling them with user-friendly applications? [Simon Inns] is lending a hand with this in his recent tutorial. He shows how to use USB capable AVR chips along with your own Windows applications.

After the break you can see the video from which the above screenshot was captured. That’s a development board of his own making which hosts an ATmega32U4, as well as a USB-B port, LEDs, potentiometer, and a few switches. Taking a closer look, we love the breadboard friendly headers he used on the bottom of the board to break out all of the pins.

His demo shows the Windows app turning LEDs on the board on and off, as well as ADC data displaying the current potentiometer position with the onscreen dial. His code package includes the hardware design, firmware, and app software needed to follow along with what he’s doing.

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