[Bunnie's] archives: Unlocking protected microcontrollers

A few years back [Bunnie] took a crack at cracking the security fuses on a PIC microcontroller. Like most of the common 8-bit microcontrollers kicking around these days, the 18F1320 that he’s working with has a set of security fuses which prevent read back of the flash memory and EEPROM inside. The only way to reset those security fuses is by erasing the entire chip, which also means the data you sought in the first place would be wiped out. That is, if you were limited to using orthodox methods.

[Bunnie] had a set of the chips professionally uncapped, removing the plastic case without damaging the silicon die inside. He set to work inspecting the goodies inside with an electron microscope and managed to hammer out a rudimentary map of the layout. Turns out that flash memory can be erased with ultraviolet light, just like old EPROM chips. Microchip thought of that and placed some shielding over the security fuses to prevent them being reset in this manner. But [Bunnie] managed to do so anyway, creating an electrical tape mask to protect the rest of the data stored in the chip while bouncing UV light underneath the shielding at an angle.

Want to uncap some chips of your own without enlisting the help of others? Give this method a try.

[via Dangerous Prototypes]

Water droplet sculpture using LEDs and Arduino

This¬†water sculpture can stop drops of water in mid-air. This is accomplished by flashing LEDs to illuminate the droplets at just the right time. But it’s not limited to blinky lights alone. The top of the frame has eight nozzles, each fed by its own pump. An Arduino controls the pumps and the lights making it possible to create different motion effects by adjusting how events line up. For instance, the image above shows just two of the water nozzles on, but in the video after the break it appears one is dripping downward while the other is dripping upward.

Alas, there’s few build details for this but the source code is available for downloading. If we were going to build one of these ourselves we’d probably try to regulate the drips using some solenoids built from scratch. How would you do it? Leave your ideas in the comments.

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Single LED ultraviolet exposure box

[Jacques Lebrac] built a UV exposure box for printed circuit boards using just one LED. He usually makes boards that are just a few square inches and didn’t think building a box that had upwards of 80 LEDs was worth his time. He passed by the low power LEDs for a single 5W unit. Pumping 1.5A through this LED makes for some quick exposures, but causes heat issues. To solve this, an aluminum arm was used to mount the LED, acting as mechanical support and heat sink at the same time. The voltage regulator was glued directly to the chassis, providing at least some heat dissipation.

[Jacques] came up with an eloquent solution for holding the transparency and copper clad in place. A piece of acrylic is hinged on the back using a piece of aluminum tubing. The front has a magnet glued to it, with another one in the base to hold the cover tight to the work surface during operation.

Building a UV exposure box

There are two methods of using etchant resist when making circuit boards. We use the toner transfer method that requires ironing on laser toner to the copper, but you can also use chemical resist that reacts to ultraviolet light. [Bogdan] decided to start doing more of the latter so he built a UV exposure box to make the process easier.

It is possible to use flourescent light bulbs for this, but he decided to use UV LEDs, a method we’ve also seen before. But there’s always room to innovate, and [Bogdan] built-in a couple of nice features that are new to us. Because the UV light can be bad for your eyes, he included a set of red visible-light LEDs on the bottom half of the box that are used to align two layers of exposure mask when making double-sided boards. There’s also a switch that automatically shuts off the UV light when the box is opened. And as the coup-de-grace, he added a programmable timer to regulate the exposure, using his newly created box when etching the PCB for it.

Mr. Burns prevents sun burns

[nmcclana] wrote out this very detailed instructible on building Mr. Burns, a sun burn alarm. ¬†Enter your skin type, sunscreen type, and UV levels for the day and Mr. Burns will let you know when it is time to go seek shelter or re-apply that sunscreen. Built on a Propeller platform, he’s using a blue LED as the UV sensor. He mentions that the device is fairly accurate, however people tend to put sunscreen on too thin and that will throw off the readings. There is a video of it in action on the instructible.

Coachella lamp

This little art piece might be just the thing to add that mad scientist look to your room. It’s called the Coachella lamp and it makes use of several throwback display devices. At the top an Argon discharge lamp puts out ultraviolet light. Protruding from each of the four sides you can see a set of decatrons. There’s also four Nixie tube bar graphs standing tall from each corner of the base. The final touch is the colored glow in the center which is provided by LEDs. We’ve embedded some video of the device after the break.

The lamp is powered by a wall outlet and controlled with an Arduino. We’ve seen deactrons used as timing devices and would love to see some clock functionality added to the lamp. Trying to decipher the time from the different Nixie displays would put this up there with some of those other hard to read timepieces.

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Monitor UV exposure with your sunglasses

Tired of those awful sunburns? [Nikko Knappe's] UV sensing glasses will warn you before you become crisp and red as a lobster. The bump added to the bridge support hides a TSL230R light frequency sensor. The device automatically switches on when the arms are unfolded and starts tracking cumulative exposure. If it detects a rising UV level, or you are about to burn based on skin type, an LED inside one arm of the frames will flash to inform you.

This has some potential if you think David Brin’s Earth outlines how climate change is really going to play out. Either way it’s still fun and we give bonus points to [Nikko] for disguising the lilypad that controls this as a flowery hair-pin.