Week in (p)review: October 28, 2011

Facebook free PCB Friday is on the way. Don’t forget to share your current project in the comments or the forum.

Here’s a summary of major developments over the last week:

Coming this week:

  • App notes on the weekend
  • Free PCB Sunday
  • Free PCBs via Twitter on Tuesday
  • Partlist Wednesday
  • Free PCBs via Facebook on Friday
  • Weekly roundup and preview every Friday

What are you hacking this week?

Bus Pirate: Modifying the EEPROM on a LED POV fan

MrZor decided to find some use for his Bus Pirate. After dissembling a LED POV fan he figured out that it uses a 24LC02B EEPROM chip to store the text displayed on the device.

The 24LC02B is a I2C device so he used the I2C mode of the Bus Pirate to interface with it. After some deciphering he figured out the code used by the device and uploaded his text. The result can be seen above, and the tutorial on how he went about doing it can be found on the forum.

Via the forum.

Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

DC power supply monitor with GLCD display

Here is a project built to provide a DC power supply with a GLCD interface:

This power supply monitor is intended to measure the voltage and current of a DC power supply, and continuously display these values on a 128X64 pixel LED backlit GLCD display.

Ezflyr built it for his aircraft ground power supply, but it could be used with any power supply that outputs voltages below 24V. It uses a onboard DC-DC converter to power the board, while the PIC16F876A uC provides the brains for the device. Once he tests it, schematic and PCB source files will be made available.

Via the forum.

Derbycon/Defcon: battery firmware hacking


We use laptops everyday and as long as the battery isn’t dead we probably don’t give it much thought. It turns out that most laptop batteries contain a smart chip which controls battery charge rate and ensures safety parameters are observed among other purposes.

In this video from the recently concluded Derbycon conference in Louisville, KY, software hacker Charlie Miller delves into the hardware and software he examined researching an Apple laptop battery. The talk includes references to code downloads which allow access to the battery communications API and techniques for hacking the firmware to possibly extend you battery’s warranty. Interesting talk on a subject you probably never thought about. (Audio clears up at around 10:00.)

You can download the code and other materials referenced in this talk from the Accuvant labs website.

This talk was also presented at Defcon 19. You can view the Defcon version here.

Free PCB coupon via Facebook to 2 random commenters


Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. More PCBs via Twitter on Tuesday and the blog every Sunday.

Don’t forget there’s free PCBs three times a every week:

  • Free PCB Sunday. The classic. Every week, get free PCBs right here on the blog comments
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs while you wait for the weekend

Continue reading “Free PCB coupon via Facebook to 2 random commenters”

Converting an Inkjet printer to print PCBs

There are many ways to built a DIY PCB. Some of the more popular ones are the toner transfer method, and the UV exposure of PCBs. Both methods require lots of trial and error.

Here is another way to go around building you PCBs. Pourcirup posted a tutorial on how to convert an old ink-jet printer to print traces onto a PCB. It is still being refined but the initial results look promising.

Via Adafruit.

CSR bluetooth tutorials

Implementing bluetooth into your project, amongst other things, allows you to get wireless interface for your design. We think it’s really cool to built devices that have the ability to talk to mobile phones, laptops, tablets, etc.

Byron is blogging about his experiences interfacing with CSR bluecore4 chips. There are instructions on how to build your own programmer via the LPT1 Parallel port. A tutorial on how to read and upgrade the firmware on a BT-to-UART module is also available on his site.

Via Twitter.

Krohn-Hite DC voltage standard teardown & calibration

Dave reviewed the Krohn-Hite DC Voltage precision power supply he bought. After checking if it was working within specs, he proceeded to open it up and see what it was made of.

There were a few surprises inside, like the resistor voltage dividers were in the standard Kelvin topology, instead of the more precise Kelvin-Varley topology. He was also shocked that the device doesn’t use a temperature controlled voltage reference. Even with these drawbacks the instrument still manages to work within spec.

Via the forum.

Velleman K8062 3rd party firmware upgrade

Velleman K8062 DIY kit is one of the most successful DMX transmitters sold world-wide, but it is also one of the poorest performers. Velleman uses an antiquated slow speed USB protocol on a device that supports Full Speed USB.

A community developed firmware upgrade that offers up to 80x times better performance is currently undergoing beta testing. It supports Full Speed USB and is developed alongside drives for multiform use.

Via the forum.

Arduino sound-responsive Halloween skull

Boris presents this project just in time for Halloween. It’s a simple Halloween skull which employs an Arduino to read the level from sound sensors and controls a servo connected to the skull’s mandible. You can see more project details and get the source code from the Open-Electronics website.

Via the contact form.

FPGACheap DIY Altera FPGA USB programmer

This is a DIY USB programer for Altera FPGAs. It only uses a PIC uC and a few discrete components to provide a JTAG interface with a FPGA. Somun found it on a Japanese site (machine translation), and with the help of Google Translate he built one for himself.

There are two versions available. The older one pictured above uses a PIC18f2550 chip, while the newer one uses a cheaper PIC18F14K50. If anyone is interested drop a comment in the forum and Somun will provide the eagle files for his build.

Via the forum.

7400 Competition: An ‘open source’ open source competition

The open 7400 logic competition is a collaborative, crowd sourced, open source competition. We started with a few prizes, but we crowd sourced our way to 20 sponsors and $1000s of dollars of swag. Judging guidelines, categories, and artwork were contributed by the community. Rules and materials are all open source, use then to get a head start on your own competition.

Without entrants, readers, judges, and sponsors, this contest would not have grown at such an accelerated rate. The competition is the product of a whole open hardware community. If you’re reading this post, you’re a contributor too! Thank you for participating.

Some things we learned:

  • Don’t be afraid to make a mistake, you can always learn from it.
  • Keep every email, contact, name, and url of everything associated with the contest. Misplace something, you’ll regret it.
  • Don’t be afraid to solicit for some sponsors in the beginning, more will follow. Start-ups and big names like to get their name out there and show support for open hardware creativity. Don’t forget to follow up. Everyone’s busy, and some things get lost in the to-do pile.
  • Most entries were submitted in a deadline rush during the last 48 hours. Make sure to have plenty of time available to run and judge the contest. Have a #2 who can help with organization and posts, you may get fatigued.

A special thanks to Sven for the 7400 competition artwork.

An extra special thanks goes to SQKYbeaver for conceiving and organizing the competition, it would never have gotten off the ground without him.

PixelController: Universal OpenSource light control solution

Pix­el­Con­troller is a real time video/VJ gen­er­a­tor and mixer with open source soft­ware developed by Michael. It generates images on a color matrix, as seen above on his PixelInvader panels. It supports many standards like Art-Net, Mini-DMX, LPD6803, and Seeedstudio’s Rain­bow­duino.

Via the contact form.

A guide to Seeed Studio’s Fusion PCB service

Luca wrote a step-by-step guide to Seeed Studio’s Fusion PCB service. It covers how to export files from Eagle and get your PCB built. It’s available both in English and Italian.

We like Fusion PCB service, it’s cheap and pretty fast. It starts at $10 for 10 PCBs ($1 per board), plus a few bucks of shipping. We’re biased though, so take our recommendation with a grain of salt.

Via the contact form.

DTMF Decoder using Goertzel algorithm on PIC18F4520


Debraj has been working on this project for DTMF decoding using the Goertzel algorithm on a PIC.

Goertzel algorithm is well known in the DSP domain. It is used to detect the presence of a frequency or a number of frequencies. This algorithm is popular as the calculation required for implementation is lesser as compared to other techniques such as DFT (FFT), when a smaller number of frequencies are to be detected.

My project uses PIC18F4520 and Goertzel algorithm to detect DTMF frequencies. The code is written entirely in “C”.

The complete explanation of the algorithm, circuit and code can be found on Debraj’s website.

Via the contact form.

Solomon soldering iron review

While working on his soldering iron driver Arhi did some research on Solomon soldering irons (machine translation). Solomon is one of the largest OEM manufacturers of soldering irons, it can be bought under various names like Nedis, Elanco, Tenma, etc. Replacement irons are cheap, under $16, making them perfect for his driver.

The most common types are the SL and HQ. The SL is a older model where the tip is placed into the heater, while the newer HQ irons have the tip slide over the heater and have a greater thermal mass. Arhi provides the standard Din-5 pinout used, as well as pictures of both irons broken down to their components.