Gravity Bike

October 9, 2012 by 73 Comments

This bicycle has no pedals and really nothing that resembles a seat. It’s not so much a way to get around as it’s a way to get down. Down from the mountain, and down low to the pavement. This is a gravity bike built by the guys at S.I.N. Cycles.

The frame is a long triangle which stretches the wheel base to make room for the rider. After getting the layout just right and welding the frame together they added the rather unorthodox building step of pouring molten lead into the hollow frame tube. This bike is used to descend a mountain road with the force of gravity, so the extra weight will help pull it just a bit faster. There’s one thing you’ll want to make sure is working before you climb aboard — the single front brake which you’ll need when coming into the curves. Check out some ride footage on this thing in the video after the break.

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Dummy Load Uses Gray Code To Adjust Load In Small Steps

October 9, 2012 by 10 Comments

We’re not really interested in building a dummy load like this one for ourselves. But the concepts behind its design make for a nice little mental exercise as you read your way through the build description. [Pabr] wanted to build a dummy load which could be used to test a cheaply made gas generator. He wanted it to be as simple as possible, while providing a range of different loads. What he came up with is this monotonically adjustable load tester which uses gray codes for switching.

The video after the break does a good job of explaining the motivation for the design. Grey coding ensures that just one bit changes at a time. The example he uses to show the importance of this is when binary code transitions from 7 (0b0111) to 8 (0b1000). Three digits have been turned off and one has been turned on. Since he’s using light bulbs for his load this will turn off 700 Watts and then switch on 800W. That sudden jump in power draw can cause all kinds of problems with the generator’s engine. But the system he wired up will ensure that each flip of a switch moves in smaller steps.

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Exploiting DFU Mode To Snag A Copy Of Firmware Upgrades

October 9, 2012 by 11 Comments

[Travis Goodspeed] continues his work at educating the masses on how to reverse engineer closed hardware devices. This time around he’s showing us how to exploit the Device Firmware Updates protocol in order to get your hands on firmware images. It’s a relatively easy technique that uses a man-in-the-middle attack to dump the firmware image directly to a terminal window. This way you can get down to the nitty-gritty of decompiling and hex editing as quickly as possible.

For this hack he used his Facedancer board. We first saw the hardware used to emulate a USB device, allowing the user to send USB commands via software. Now it’s being used to emulate your victim hardware’s DFU mode. This is done by supplying the vendorID and productID of the victim, then pushing the firmware update as supplied by the manufacturer. In most cases this shouldn’t even require you to have the victim hardware on hand.

Teens Pulled Over While Driving Their Wooden Roadster

October 9, 2012 by 49 Comments

From this view we would think the handmade wooden roadster (translated) was street legal. But it’s missing a few items that are required to take it out on the highway. The teenagers that built it were pulled over the other night (translated) and cited for driving without a speedometer or side indicator lights.

The image above shows the mark II of their design. Sadly they crashed the first version, which gave them a chance to overhaul the entire design. Now they have a proper frame which was welded from steel square tube. It’s got an impressive rack and pinion steering system and shock absorbing suspension in the front and rear. A dirt bike engine mounted behind the seats drives the rear wheels via a chain. They’ve used an Arduino to add turn signals, and have headlights for night driving.

[Gerrit] sent in the tip on this one and he figures that with an Arduino already being used in the vehicle it should be a quick fix to add a speedometer and get back on the road.

Bootloader Brings USB, Firmware Updating To The ATtiny85

October 9, 2012 by 14 Comments

[Jenna] sent in a very cool bootloader she thought people might like. It’s called Micronucleus and it turns the lowly ATtiny 85 into a chip with a USB interface capable of being upgraded via a ‘viral’ uploader program. Micronucleus weighs in at just over 2 kB, making it one of the smallest USB-compatible bootloaders currently available.

The USB support comes from V-USB, a project that puts a virtual USB port on a suite of AVR microcontrollers. With V-USB, it’s easy to turn a Tiny85 into a keyboard, custom joystick, data logger, or computer-attached LED display.

One very interesting feature of Micronucleus is the ‘viral updater’ feature. This feature takes a new piece of firmware, and writes it to a Tiny85, disabling the current bootloader. If you’re designing a project that should have a means of updating the firmware via USB instead of the usual AVR programmer, this might be the bootloader for you.

Not bad for a bootloader that emphasizes small code size. At just over 2 kB, it’s possible to use this bootloader on the similar, smaller, and somewhat cheaper ATtiny45.

Bringing Java To The World Of Microcontrollers

October 9, 2012 by 104 Comments

C is a beautiful language perfectly suited for development on low-power devices such as the 8-bit microcontrollers. With newer, more powerful ARM microcontrollers making their way onto the market and workbenches around the world, it was only fitting that Oracle got in on the action. They released a version of Java targeted at these newer, more powerful microcontrollers called Java ME embedded.

The new embedded version of Java has everything you would expect from a microcontroller development platform – access to GPIO pins, including SD cards and I2C devices. The new Java machine is designed for full headless operation and is capable of running on devices with as little as 130 kB of RAM and 350 kB of ROM.

As for the utility of programming a microcontroller in Java, it’s still the second most popular language, after spending the better part of a decade as the number one language programmers choose to use. The requirements of the new embedded version of Java are far too large to fit onto even the best 8-bit microcontrollers, but with a new crop of more powerful ARM devices, we’ll expect to see more and more ARM/Java projects making their way into the Hackaday tip line in the coming months.

Tip ‘o the hat to [roger] for sending this one in.