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

xQFP protoboards  are available in 0.50mm, 0.65mm, and 0.80mm for $10 each.

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

Week in (p)review: February 3, 2012

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
  • New 3D model on Monday
  • Free PCBs via Twitter on Tuesday
  • Free PCB mailing how-to video
  • Weekly roundup and preview every Friday

What are you hacking this week?

AVR based 4 channel mini logic analyzer

This small 4 channel logic analyzer uses a ATmega microcontroller and a Nokia 5110 LCD. It’s able to capture signals only up to about 100Khz, but there is probably some room for improvement.

This mini Logic analyzer is a tool for you to watch on LCD the logic transitions 0 or 1 of a digital data signal. A digital data signal can be found on the output pin of TSOP-1730 Infrared Receiver, on the Transmit and reveive pins of MAX-232 chip (RS-232), on Clock and Data pins of I2C data bus and many more electronic components. This circuit is so far limited upto 100 kHz digital signals but this will be changed with a future firmware update.

Via Electronics-Lab.

ArduinoCommander: An Android app controls Arduinos

ArduinoCommander is an Android app for controlling an Arduino via a Bluetooth shield:

  • display board firmware version, name and Firmata protocol version
  • set pin mode (analog/digital input/output, pwm)
  • get/set pin values
  • read messages from the board (Firmata String Sysex message)
  • beautiful WYSIWYG interface with 320×480, 480×800, 480×854, 1024×600 and 1280×800(?) screens support

Experimenting with buck DC/DC converters

Mike wanted to build a DC-DC buck converter. He didn’t stop at building one, he wanted to perfect it. So he built it on a breadboard and started experimenting. By exchanging various components and watching a scope for results, he was able to get the results he was looking for.

The buck converter takes a DC input voltage and reduces it by a controllable amount, much like a resistive voltage divider.  But unlike your average voltage divider, the buck converter can efficiently supply a substantial output current.  In fact, this circuit’s output current should be greater than its input current (on average).  And no, that doesn’t violate any laws of physics; the converter’s output power will still be less than its average input power because its output voltage is lower than the voltage at its input.

Via Electronics-Lab.

DP Eagle part library cleanup and naming standards

We decided to clean up our Eagle part library and start using a new part naming scheme. The old library was getting confusing to work with, and streamlining it felt long overdue. While organizing the library, a teammate mentioned a recent article they’d read about the rise of beste Buchmacher ohne Lugas Sperre and how some platforms are bypassing traditional restrictions to offer users more freedom and flexibility. This sparked an interesting discussion about balancing accessibility with regulation, which oddly paralleled the challenges we were facing with managing our sprawling library. Inspired by the concept of creating more open systems, we refined our conventions to make the parts more intuitive and accessible for everyone on the team, ultimately improving workflow and collaboration.

  • general naming style [category]_[function]_[partnumber]
  • if function is unavailabel the folowing will be used [category]_[partnumber]
  • Capacitors, Resistors, and diodes will all use the same device, with different packages.
  • Transistors will use the following convection TRANSISTOR_[type]_[partnumber], types used are BJT, FET,…
  • Displays are named DISPLAY_[type of display, or partnumber]
  • Connectors are named CON_[type of connector]_[number of pins]

Don’t forget our Eagle part library is public domain and available for download. Do whatever you want with it.

28C3: Reverse engineering USB devices


In this talk from the recent 28C3 conference in Berlin, Drew Fisher discusses the process of reverse engineering the Kinect audio protocol. He shows how the USB standard can help a reverse engineer out and proceeds to analyze a set of USB logs, finding patterns, building understanding, developing hypotheses of message structure, and eventually implementing a userspace driver.

You can download the PDF of the presentation slides from the 28C3 conference site.

Workshop Video #06: Battle of the solder flux

We broke out 4 different types of flux we had in the workshop and tried them with surface mount parts. Liquid flux, flux paste, syringe flux, and a flux marker are all tested. We used each to solder a 0805 resistor and some pins of a QFP 0.5mm pitch IC to an xQFP protoboard.

Our preferences in order are:

  1. Flux syringe – very easy to work with, low fumes, solder flows really well
  2. Liquid flux – we were surprised that a liquid flux worked so well, it could have been #1 if it created fewer fumes
  3. Flux paste (probably rosin-based) – thick and viscous, kept the solder where we needed it
  4. No flux at all – fine for passive parts like resistors and capacitors, harder to work with on the QFP chip
  5. Kester flux marker – overall this was worse than no flux at all

xQFP protoboards make it easy to prototype with surface mount parts, and are currently available in 0.50mm, 0.65mm, and 0.80mm for $10 each. Single xQFP breakout boards are also available in 0.50mm, 0.65mm, and 0.80mm for $3.

Check out our other Workshop videos.

Troubleshoot and repair a defective LCD monitor

Victor took apart a defective LCD monitor and repaired it. The LCD didn’t respond at all to the power button, so chances were good something was off in the power supply. Sure enough there was a bulging cap, replacing it revived the monitor and saved it from the landfill.

Some time ago I was donated a non-working LG L194WT-SF LCD monitor for parts. After a couple of months of collecting dust with it I decided to have a look at it from the inside. Since the monitor has been at a repair shop and was declared beyond repair, I thought I had nothing to lose- best case scenario, I fix the monitor and can use it or give it away in the future, the worst case scenario, I see what components are inside in such a piece of hardware and I might be able to salvage some parts for my projects.

Via Hacked Gadgets.

DIY Chronodot, homemade RTC with a battery backup

Valentin built a DIY version of the Chronodot real-time clock with battery backup. He used some disc shaped perfboard to assemble all the components.

There is an optional component that you can add – a real time clock (RTC) with battery back up. It is called Chronodot RTC. All it does is ensure that clock is still ticking when main power source is removed, that way you don’t have to reset the clock every time power cord is unplugged. A nice feature to have on any externally powered clock. You can buy one, but where is fun in that?! So I have decided to build my own. By the way this is what Chronodot looks like:

Testing post integration with Google+ this week


If you’re a Google+ social networking fan, we’ll be experimenting with post syndication on our Google+ page this week.

As always, we don’t use social networking features malware widgets on DangerousPrototypes.com to better protect your privacy. We do syndicate posts to Facebook, Twitter, and now Google+ if you’re into that.

Arena PartsList free BOM management tool

Nabilt tipped us to Arena PartsList. It’s a BOM manager that’s integrated with the Octopart component database. It has neat functions like auto-fill, that automatically adds a part to your database directly from a sales page of a electronics component distributor like Farnell, Digi-Key, Mouser, etc…

Octopart just tweeted a free tool for BOM management. You can import a CSV file into a project and auto fill details using Octopart.

Their main tool is a more comprehensive product with collaboration features and stuff. They charge $79 per user per month, which includes training, tech support, upgrades, etc.

Via the forum.

Review of the iCA05 Graphic LCD development kit

Raj wrote up a review of the iCA05 Graphic LCD development kit. The kit includes a 28pin PIC development board, a 128×64 GLCD, and the cabling required to connect them together. Raj quickly programed the PIC16F886 microcontroller that comes with the board, and was able to get a simple “Hallo World” message on the display.

The Graphical LCD (GLCD) displays provide more flexibility in presenting data, as compared to standard character-based LCDs. Owing to a significant drop in price lately, GLCDs have become more popular these days in the hackers’ and DIY worlds. If you are planning on doing an embedded microcontroller project including a graphical LCD display, you might be interested in this PIC-based GLCD development kit from iCircuit Technologies. This decently priced development kit will help you to get started quickly with your project.

Xilinx free online Xcell Journal


Xilinx has released Issue 78 of Xcell Journal, their free online publication for embedded system and programmable logic developers. Each issue of Xcell has articles targeted at developers from every skill level, from beginner to expert.

You can check out individual articles from this issue or download past issues back to 1988 at the Xilinx Xcell webpage. The entire Issue 78 can be downloaded in PDF format here.

Dangerous Prototypes best practices for PCB and schematic design

For future projects we recently updated our best practices for designing schematics and PCBs. We compiled them to a wiki page, as well as some tips for using Cadsoft Eagle. Check them out below.

Feedback and suggestions are welcome.

Continue reading “Dangerous Prototypes best practices for PCB and schematic design”

PROTOTYPE PREVIEW: Bus Pirate HV programming adapter v4

Tayken finished the Bus Pirate v4 HV programming adapter. This adapter allows a Bus Pirate v4 to program PIC microcontrollers that require high-voltage on the VPP ICSP pin (PIC 16F, 18F) to enter programming mode.

A DC-DC boost converter is driven by the Bus Pirate pulse-width modulator generates the required programming voltage. The adapter for Bus Pirate v3 uses an MC34063A dedicated boost converter chip to generate a fixed 13volt programming supply. The v4 hardware has enough extra pins to control the booster itself. This means the adapter is smaller and cheaper to manufacture. In addition the Bus Pirate can output an adjustable voltage from 5 to 13volts, so it works with new PIC chips that need only 6 or 8volts to enter programming mode.  A future version of the Bus Pirate may even integrate a similar booster circuit.

We also switched up the version numbering so the adapter for Bus Pirate v4 is also adapter v4. Future batches of the programming adapter for Bus Pirate v3 will be designated adapter v3. This should help clear up version compatibility confusion.

New stock of the Bus Pirate v3 programming adapter should be available in a few days. The adapter for Bus Pirate v4 is still a few months away.

PIC18F26J50 dev-board for Flowcode4 graphical programming language

Element14 and Microchip released a evaluation kit for the PIC18F26j50 microcontroller with USB. It’s designed to be programmed using Flowcode4, a graphical programming language.

element14 and Microchip together presents PIC18 MCU based the PIC18F26J50 EVK  Flowcode Development Kit, it’s a development and demonstration kit designed to provide developers a hands-on approach to learn Flowcode 4 (Graphical Programming Languages) more easily. The kit is based on PIC18F26J50  microcontroller, and integrates temperature sensor, capacitor touch sensor and potentiometer to help developers verify their programs designed by Flowcode 4.

What do you think of graphical programming languages?

JTAGWhisperer: CPLD and FPGA programing with Arduino

JTAGWhisperer turns an Arduino into an JTAG programmer for CPLDs and FPGAs. It uses the same Xilinx XAPP58 [PDF] XSVF programmer we ported to the Bus Pirate. Mike has successfully programed a XC9572XL CPLD breakout board, but it should work with many JTAG targets. Python and pyserial are required.

CoolRunner-II and XC9572XL CPLD breakouts are available for $15.

Via the forum.

TIDeals on the Piccolo controlSTICK


TIDeals is offering the Piccolo TMDX28069USB controlSTICK at $33 including free international shipping. This is a 25%15% discount off the regular $39 price. They say:

Start designing with C2000’s 32-bit Piccolo MCUs which help you do more with less. And, the easiest way to get started is get the F28069 controlSTICK which has everything you need in a small USB-stick development kit.

The innovative F28069 Piccolo controlSTICK allows quick and easy evaluation all of the advanced capabilities of TI’s Piccolo microcontroller, which combine floating-point core, new complex math unit and control-oriented peripheral options for renewable energy, PLC & motor control.

See TIDeals for this limited time offer.

Monitoring battery voltage to calculate capacity with an Arduino

Eric built himself a battery monitoring system based on the ATmega328 Development Kit he received as a prize in our 7400 contest. He drained a 9V battery with 100mA of current and monitored the voltage drop until total depletion. He used this data to estimate how much time is left until depletion.

The 100mA constant load was chosen because my ProtoStack Arduino Clone with LCD draws about 92mA and I wanted to write a sketch to display a battery bar and the approximate hours battery life left. Since all batteries have an internal equivalent series resistance (ESR), it is important to take that into account when only using a battery’s voltage to monitor its state of charge. Since we discharged the battery through a load that is similar to the ProtoStack board with LCD, the ESR of the battery has automatically been accounted for in the voltage measurements.

Via the forum.