Pseudo-Random Flickering Jack-O-Lantern LED using ATtiny13

Pseudo_Random_Flicker_ATtiny13

It’s time to get those jack-o-lanterns twinkling for Halloween. If you don’t want to use candles or buy a jack-o-lantern light this Halloween you can do like [Johannes Bauer] and code your own pseudo-random flickering super bright LED. His wife wanted their pumpkin to be illuminated this year and he knew it would be easy to do with an Arduino, but that would be overkill for such a simple project. Plus, he doesn’t have an arduino. [Johannes] used very few components; 4 slightly depleted AA batteries, a super bright LED, 680 ohm resistor and a little custom code on an 8 pin ATtiny13. The circuit does work great for a pumpkin lantern but his video is more of a tutorial on coding linear congruential generator (LCG) for the 8 bit pseudo-random LED flickering.

The code is short and can be gleaned from the YouTube video. [Johannes] used avr-gcc to compile and has packaged his code and build scripts for download. The hex file can be flashed over to the chip using avrdude or AVR Studio. If you have any ATtiny13s lying around you should cobble this hack together just in time to emulate that real look of a pumpkin candle without the hassles and hazards of real flames.

If you want something with a lot more light that still has that candle like flicker then checkout “Flickering Pumpkin Lanterns” that used the signal from LED tea lights to power some 12 V lamps.

Follow along after the break to watch [Johannes Bauer’s] video.

[Read more...]

Cracking GSM with RTL-SDR for Thirty Dollars

GSM

Theoretically, GSM has been broken since 2003, but the limitations of hardware at the time meant cell phone calls and texts were secure from the prying ears of digital eavesdroppers and all but the most secret government agencies. Since then, the costs of hardware have gone down, two terabytes of rainbow tables have been published, and all the techniques and knowledge required to listen in on cell phone calls have been available. The only thing missing was the hardware. Now, with a super low-cost USB TV tuner come software defined radio, [domi] has put together a tutorial for cracking GSM with thirty dollars in hardware.

Previous endeavours to listen in and decrypt GSM signals used fairly expensive software defined radios – USRP systems that cost a few thousand dollars a piece. Since the advent of RTL-SDR, the price of software defined radios has come down to about $30 on eBay, giving anyone with a Paypal account the ability to listen in on GSM calls and sniff text messages.

The process of cracking GSM first involves getting the TMSI – Temporary Mobile Subscriber Identifier – a unique ID for each phone in a certain cell. This is done by sending a silent SMS that will send back and acknowledgement an SMS has been received on the victim’s phone, but won’t give the victim any indication of   receiving a message.

From there, the attacker listens to the GSM signals in the cell, receiving bursts attached to a TMSI, and cracking the encrypted stream using 1.6 TB of rainbow tables.

[domi] put up a four-part tutorial series (part 1 above; part 2, part 3, and part 4) that goes over the theory and the actual procedure of cracking text messages and voice calls with a simple USB TV tuner. There are a few limitations; the attacker must be in the same cell as the victim, and it looks like real-time voice decoding isn’t yet possible. Cracking GSM for $30, though, that’s good enough for us.

USB Implementers Forum Says No to Open Source

USB

For the longest time. one of the major barriers to hobbyists and very small companies selling hardware with a USB port is the USB Implementers Forum. Each USB device sold requires a vendor ID (VID) and a product ID (PID) to be certified as USB compliant. Adafruit, Sparkfun, and the other big guys in the hobbyist market have all paid the USB Implementers Forum for a USB VID, but that doesn’t help the guy in his garage hoping to sell a few hundred homebrew USB devices.

Arachnid Labs had an interesting idea to solve this problem. Since other USB device vendors such as Microchip and FTDI give away USB PIDs for free, a not for profit foundation could buy a VID, give PIDs away to foundation members making open source hardware, and we would all live in a magical world of homebrew devices that are certified as USB compliant.

This idea did not sit well with VTM Group, the people serving as the management, PR, legal, and membership and licensing department of the USB Implementers Forum. In a slightly disproportionate response, the VTM Group told Arachnid Labs to,

Please immediately cease and desist raising funds to purchase a unique USB VID for the purpose of transferring, reselling or sublicensing PIDs and delete all references to the USB-IF, VIDs and PIDs for transfer, resale or sublicense from your website and other marketing materials.

Interestingly, Arachnid Labs’ and scores of other requests for an open source USB VID haven’t hit the desk of anyone at the USB Implementers Forum, the people who are actually in charge of designating USB VIDs and PIDs. There are a number of ideas to get around VTM Group that include squatting on USB VID 0xF055, but we’re at a loss why there couldn’t be a foundation that gives out open source USB PIDs. Microchip, FTDI, and Openmoko do the same, so perhaps it’s time to email some key people at HP, Intel, and Microsoft

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