#FreePCB via Twitter to 2 random RTs

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Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters.

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

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

An Ultrasonic eye for the visually impaired

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Dhavalis build this Netra project, an ultrasonic eye for the visually impaired:

Netra is an eye for visually impaired, a device based on Echolocation principle. It uses Arduino Micro, Ultrasonic sensor and vibrating motor. Vibration of the motor increases with decrease in distance and vibration decreases with increase in distance between device and object in front. Build this device for people suffering from Retinitis Pigmentosa Disorder.

Via the Arduino blog.

Homemade GPS receiver update

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Andrew Holme posted an update on his DIY GPS receiver  we covered previously:

This is now a truly portable, battery-powered, 12-channel GPS receiver with turnkey software, which acquires and tracks satellites, and continuously recalculates its position, without user-intervention. The complete system (below, left) comprises: 16×2 LCD display, Raspberry Pi Model “A” computer, two custom printed-circuit boards, commercial patch antenna and Li-Ion battery. Total system current consumption is 0.4A for a battery life of 5 hours. The Raspberry Pi is powered through the ribbon cable linking its GPIO header to the “Frac7” FPGA board and requires no other connections.

GrrCON 2013 – Pwnage from the Skies!


At the GrrCON 2013 conference last Fall, Philip Polstra presented on the use of the AirDeck Linux based aero mobile pen testing device.

This presentation will introduce the AirDeck which is the latest extension to The Deck penetration testing and forensics program. The Deck made its US debut at GrrCON 2012. The Deck is a complete penetration testing and forensics Linux distribution that runs on the BeagleBoard family of small computer systems. Since its debut several modules have been released for The Deck. The 4Deck module provides USB write blocking for forensics work. The MeshDeck module allows an army of devices running The Deck and connected by 802.15.4 Xbee and/or Zigbee mesh networking to perform coordinated attacks from distances of up to a mile. The AirDeck represents the next evolutionary step to The Deck. The AirDeck is a flying wing which runs The Deck. The AirDeck is capable of vertical takeoffs and landings and can also be flown as an airplane. This allows a penetration tester to literally fly an attack device to the target organization and land somewhere where the device will go unnoticed (such as a roof).

This will be the worldwide debut of the AirDeck platform. The presenter says that full specifications and code for the AirDeck and other modules will be provided.

GrrCON is an annual information security and hacking conference in Grand Rapids, MI, put together to provide the community with a venue to come together and share ideas, information, solutions, forge relationships.

Diode temperature sensor calibration using Arduino and SHT15 module

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Paulo writes:

A simple diode or the output of a transistor bias circuit can be used as a rough temperature sensor. For this purpose, a calibration procedure using a precise temperature sensor is recommended. This article shows how to calibrate such a temperature sensing circuit using an Arduino and the SHT15 Sensirion temperature/humidity sensor module.

504 Segment clock, a 7-segment clock done differently

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Bertho  has designed and built this cool 7-segment clock, the 504 Segment clock:

At some point I was being silly and got the idea of making a 7-segment clock, but then a bit different. The result became this.  Features include:

  • 72 7-segment displays in three rings; inner (hour) ring 12 displays, middle (minute) ring 24 and outer (seconds) ring 36 displays
  • Light sensor for adaptive display intensity; lighter during the day, dimmed at night
  • Movement sensor for waving interaction; show time/date with a wave of your hand
  • Each segment individually addressable with 256 levels of intensity
  • Ethernet connectivity for remote control and power entry
  • NTP synchronization for (near) perfect time
  • Some blinkenleds for indicative purposes
  • Buttons and RTC for off-line time-keeping
  • 3D printed case in four sections with Plexiglas cover and back

Via the project log forum.

Open source hardware GPIB USB Adapter

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scasagrande shared his GPIBUSB Adapter rev3 in the project log forum:

This past weekend I finally finished up the third major revision of my GPIBUSB adapter board. Major hardware changes include swapping the pull-up resistors for the proper GPIB line drivers, as well as swapping the FT232RL for the newer FT230X. There is a number of software improvements from improved reliability to additional commands.

All source can be found at Github.

Via the forum.

STM32F429 discovery board running Sega master system emulator

Fabrice Muller writes informing of this recent efforts using the STM32F429 Discovery Board to run a Sega emulator:

Yesterday I made this adaptation from the Alessandro Rocchegiani sega master system emulator. You can seen the original work here. After trying to adapt this emulator to my smt32 VGA output board I faced some problems with rotating and scaling the pixels with the dma2d system. Alessandro and his Son Fabrizio helped me a lot here and I have to say that it was not that easy. After some hours of programming / testing / (Fabrizio at debugging ) and interposed e-mail we get a great result! Now it is running at 640 x 480 in 16bits, and I use the Wii classic controller. The ROM is read into the emulator from the SD Card.

The video above shows when the emulator finally got its first breath. You can get all information for this version of the Emulator, VGA board, Wii Library, etc., on my Google page.
.,
I hope you will enjoy the way we can use the new ST429 discovery board.

Via the contact form.

Free PCB Sunday: Pick your PCB

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We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Universal serial bus power management

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See this app note from Micrel on USB power requirements and distribution.

Power management and distribution is a major factor in
correctly designing USB (Universal Serial Bus) peripherals.
Proper methods of designing USB peripheral power distribu-
tion are crucial to ensure full compliance with the USB
specification, including compliance with electromagnetic in-
terference (EMI) and voltage regulation requirements.

App note: Design considerations for 5V to 3.3V pass regulators

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Great app note from Micrel on thermal management for voltage regulators.

This note discusses the LDO option, including choosing between simple three terminal regulators and full-featured five terminal regulators, and provides formulas, calculations, and a selection of commercial heat sinks for powering 3.3V logic circuitry requiring up to 5 amps from a standard +5V supply. Additionally, a “trick” for reducing heat sink requirements by distributing power dissipation with a series resistor is discussed.

App note: Interfacing 3V and 5V applications

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Another app note from NXP/Phillips Semiconductor on I/O voltage level shifting.

Many reasons exist to introduce 3V systems, notably the lower power consumption for mobile applications and the introduction of parts that use technologies with such fine geometries that 5V is simply not allowed any more.
The introduction of the 3V standard as supply voltage has resulted in many design activities for digital systems. Very often, however, there is a gradual transition from 5V to 3V, since not always are all required components available, or the system is rather complex so that 3V is introduced in part of a system. As an example, customers wish to use an existing and proven CPU, while a new, more complex ASIC with added features can only be made with 3V. Or vice versa!
With the introduction of new standards such as 2.2-2.7V or even 1.7V we expect that interfacing between systems that use different supply voltages will be an actual issue for many years to come. This application note specifically addresses the interfacing between 3V and 5V systems, but the results can be applied for interfacing between other voltage levels as well.
We will discuss how one can ensure reliable information exchange and how to prevent current flow between both supply voltages when interfacing logic with memories, ASICs, PLDs and microprocessors at different supply voltages.

An ARDUINO Yun security guard

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Boris Landoni from Open Electronics  writes:

Let’s capitalize on the Yun Arduino new features to create an electronic “guard dog”, which allows you to watch your stuff, a hidden corner of the backyard or our car silently laying in the garden.
Here we wanted to face a small project, but one you would not be able to do with old Arduino boards. Connect a webcam, being able to display images on a web browser and activate actions if “something” or “someone” moves into the field that we want to hold on check. After an event trigger we could be alerted by Twitter, reusing the example proposed, or by e-mail, or even with the lightening of a notification LED.

Free PCB coupon via Facebook to 2 random commenters

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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 every week:

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

Online course – Embedded Systems: Shape the world


Jonathan Valvano, professor at The University of Texas at Austin informs us of his upcoming embedded systems course.

Myself and Professor Yerraballi are teaching a course this semester in collaboration with edX called UT.6.01x Embedded Systems: Shape the world. It is an online class (aka MOOC) introduction to embedded systems. The class starts Jan 22 2014 and is unique in that it requires hardware, we believe that embedded systems cannot be taught without hardware, thus we are innovating and creating the first online class with a physical world lab component.

Students will need either a Stellaris LaunchPad or a Tiva LaunchPad. All the projects developed in this course will run on either of these MCU boards.

More information can be found on the UTexas course website and the edX course site.

While there is a fee for those requesting certification of completion, it is free for those who wish to audit the course.

Week in (p)review January 10, 2014

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Here’s a summary of major developments over the last week. Free PCB Friday is coming up soon.

Coming up:

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

A new open source 200MHz logic analyer

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Here’s an interesting open source 200MHz logic analyzer project on Kickstarter, the DSLogic by DreamSourceLab:

DSLogic consists of DSLogic-Core and extension modules. DSLogic-Core is a re-configurable circuit board based on FPGA technology with maximum 200MHz sampling rate and 64Mbit on-board memory. DSLogic-Core can work alone as a fully functional logic analyzer, along with various extension modules.DSLogic can also work as oscilloscope, data acquisition system, protocol analyzer and even RF analyzer.