Designing PCBs for automotive applications

This application note gives PCB design tips for reducing EMI in automotive environments. A lot of the advise can be applied to any PCB layout.

Electromagnetic interference (EMI) and electromagnetic compatibility (EMC) testing is an important part of design verification for serializer/deserializer (SerDes) devices in automotive applications. EMI and EMC must be considered early in the design cycle to prevent needless design revisions. The following application note details helpful, basic concepts and guidelines on how to prepare your SerDes system for EMI/EMC testing.

Thanks rsdio!

TurtleBot: a Kinect on wheels

Willow Garage has announced plans for the release of their TurtleBot robot kit. The kit is a combination of their iRobot Create, a Kinect, netbook, and gyro integrated together. Picture an Asus netbook riding on a Roomba with top-mounted Kinect for cyber vision all controlled by open source software and capable of running your own apps. They say TurtleBot can explore your house on its own, build 3D pictures, bring you food, take panoramas, and more.

TurtleBot comes with an open-source SDK based on ROS to help you develop robotic applications right out of the box.

The bot isn’t exactly cheap, costing around $1200 for the complete kit. But the combination of a Kinect, Asus netbook and open source dev software makes it a platform the dedicated robot hacker may want to consider.

App Note: Versatility of CTMU

This Microchip application note explores the many uses for the Charge Time Measurement Unit (CTMU). CTMU is a flexible analog module that provides accurate differential time measurement between pulse sources, as well as asynchronous pulse generation. Together with other on-chip analog modules, the CTMU can be used to precisely measure time, measure capacitance, measure relative changes in capacitance or generate output pulses that are independent of the system clock. The CTMU module is ideal for interfacing with capacitive-based sensors.

This app note illustrates that CTMU principles extend beyond just capacitive touch sensors. Forty-eight applications are presented including proximity sensors, stud finders, occupancy sensors, liquid level sensors as well as using CTMU with a microphone to detect capacitive changes in a microphone’s element which can then be read by a MCUs A/D converter. It also covers the CTMUs use in measuring relative capacitance, absolute capacitance, reactive inductance, precision time and resistance when interfaced with appropriate sensors.

CTMU is found on a number of Microchip PICs, such as the PIC24FJ64GA102.

Chip powers LED lamps in MR16 halogen bulb systems

This driver is used in LED replacement lamps for MR16 halogen bulb sockets. It’s compatible with common dimmers:

The MAX16840, an LED driver that employs a proprietary architecture to ensure flicker-free, dimmable operation with electronic transformers and cut-angle dimmers. Maxim’s patent-pending approach enables the design of retrofit LED lamps that can replace halogen MR16s without any changes to the existing electrical infrastructure. This removes an important obstacle to commercial viability, allowing end users to enjoy all the benefits of LED lighting with substantially lower deployment costs.

Thanks for the tip rsdio!

Waterwall device spooks cats

We found this Waterwall project on the Sump.org site, and while its an oldie it’s just too funny to pass up.

This project is the logical result from combining my wish to keep them out of my room with their natural fear of water. So far they had proven very hard to teach about my room. This means the solution had to be automated and on guard 24 hours a day. The idea for waterwall was born and now has become real. For entertaining purposes and lack of other use I threw my webcam in to – hopefully – get some nice pictures.

The Waterwall employs an IR intrusion sensor to detect the presence of a cat, which then activates power to a windshield washer pump which sprays water at the cat. This is only half the fun: the device is connected via the parallel port to a computer, running a script which activates a webcam to capture the event for posterity!

The design is an old one, and could be updated using an Arduino communicating with the PC via serial or USB, with a Processing script to control the webcam.

TI TMS320C5000 DSP dev-board

TI has new credit card sized dev-boards for the TMS320C5000 digital signal processor (DSP):

The C5502 eZdsp development tool, which includes a range of integrated peripheral devices along with an XDS100v2 JTAG emulator, a complete version of the industry-leading CCS IDE v4 and access to chip support, optimized DSP, Image and Telecom library with source code, is available now at the low cost of USD $89

The C5509A eZdsp development tool is also available now at the low cost of $99 and includes a USB1.1 slave port and a microSD card slot in addition to the C5502 eZdsp USB development tool features.

The USB connected eZdsp dev boards target applications such as voice, audio, musical instruments and accessories, medical monitoring and fingerprint biometrics.

Thanks Drone! Via the contact form.

1.8V/3V sim card power supply with level translator

McZ found a sim card power supply with level translator:

The TXS4555 is a complete Smart Identity Module (SIM) card solution for interfacing wireless baseband processors with a SIM card to store I/O for mobile handset applications. The device complies with ISO/IEC Smart-Card Interface requirements as well as GSM and 3G mobile standards. It includes a high-speed level translator capable of supporting Class-B (2.95 V) and Class-C (1.8 V) interfaces, a low-dropout (LDO) voltage regulator that has output voltages that are selectable between 2.95-V Class-B and 1.8-V Class-C interfaces.

Thanks McZ!

NimbleSig III RF analyzer using Renesas RX62N

Va7sa designed this RF analyzer as his entry in the Renesas RX design contest. He writes:

The NimbleSig III RF Analyzer is a compact, relatively inexpensive instrumentation cluster intended for analyzing the transmission characteristics of RF circuits designed to operate within the frequency range of 200 KHz to 200 MHz.

The analyzer is capable of generating a pair of frequency agile RF signals with digital accuracy. It has measurement capabilities for gain/loss, phase shift and low level RF power. A tracking generator sweep system mode provides a high dynamic range swept frequency display of circuit amplitude response characteristics. A spectrum display mode permits the viewing of signals in the frequency domain.

The RX62N RDK was a solid choice for the controller. It provides control logic and comms for the various RF modules and for the human-machine interface, 4.3″ touch screen SLCD display. The powerful RX62N RDK with its abundance of connectivity options and supporting peripheral devices provides a paved road for a number of planned enhancements for this instrument.

For an exhaustive description of this project, download this 58 page PDF.

The NimbleSig III is one of the finalists in the contest and proceeds to final round of judging at the Embedded Systems Conference in May in San Jose, California.

Mini robot design using CoolRunner-II CPLD

It’s National Robotics Week, and what would National Robotics Week be without a CPLD based mini robot design? Here’s a mini robot design project outline (PDF!) found in the World Academy of Science, Engineering and Technology journal.

While it’s not a “how to” style article (no schematic/code provided), it describes the advantages of using CPLDs in robot design and highlights the considerations involved.

Their design uses the XC2C32A CoolRunner-II chip, which is the smaller version of the chip used in our CoolRunner-II Development Board.

FCC adopts spread spectrum rules changes

According to the ARRL, the FCC has adopted changes to the rules governing the use of spread spectrum radio transmissions by US Amateur Radio operators. The rule changes, which take effect April 29, 2011, eliminate the requirement that amateur stations transmitting Spread Spectrum use Automatic Power Control (APC) to reduce transmitter power. This requirement proved to be impractical, and was a reason for the lack of more active experimentation using this transmission mode. At the same time, the Commission has reduced the maximum power of a spread spectrum emission from 100 to 10 Watts PEP.

The spread spectrum mode of radio transmission is one of the unique wireless modes making amateur radio licensing more attractive and relevant to hackers today, as noted in this Defcon16 video presentation.

The FCC Report and Order explaining the rules changes is available here.

Free Bus Blaster v2 PCB via Facebook comments

This week we’re trying a new PCB giveaway via Facebook and Twitter. The first few people who comment on this post on Facebook get free PCBs. This is our first test, apologies all around if the title gets smashed or something goes wrong. Be the first to get see this post next week, like us on Facebook.

Get a Bus Blaster v2 for $34.95 only at Seeed Studio. Hurry, the first batch is nearly gone!

Continue reading “Free Bus Blaster v2 PCB via Facebook comments”

Week in (p)review: April 15, 2011

Don’t forget to share your current project in the comments or the forum. Everyone who posts a project log this week gets a free PCB!

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

Coming this week:

What are you hacking this week?

Internet-based temperature logger with mbed and ThingSpeak

Frank setup a internet-based temperature logger using the ThingSpeak contest data-logging service:

This project uses a mbed microcontroller (LPC1768 ARM Cortex-M3) to monitor temperature using a DS1620 (digital temperature sensor IC), retrieve the time via NTP (network time protocol), and then log the current temperature to ThingSpeak along with a time-stamp.

See a live graph here.

Via the forum.

Radiation sensor board for Arduino

David writes:  We are very glad to announce we have just uploaded all the information of the Radiation Sensor Board

The main finality of the Radiation Sensor Board for Arduino is to help people in Japan to measure the levels of radiation in their everyday life after the unfortunate earthquake and tsunami struck Japan in March 2011 and cause the nuclear radiation leakages in Fukushima. We want to give the chance to measure by themselves this levels instead of trusting in the general advises which are being broadcasted. The usage of this sensor board along with the affordable and easy to use Arduino platform helps people to get radiation values from specific places.

Via the contact form.

Pyro propeller clock POV

Chris from PyroElectro writes:

After having seen so many propeller clock POV videos on Youtube, but no real description of how they work or how to build your own, I set out to make one and document how it was built. The Pyro Propeller Clock POV design criteria was short and sweet: be as simple as possible in order to encourage others to make their own, DIY style.

The clock’s main components are a PIC 18F252, 74LS373 latches, and a 3800 RPM fan. (Note that “propeller” in the title comes from the rotational property of the design; the project does not use a Parallax Propeller MCU.) Checkout PyroElectro for the complete project description, including build instructions, schematic and code.

Thanks Chris! Via the contact form.

Reversible motor control for Arduino and other MCUs


Nothinglabs has posted their circuit for a simple reversible motor control for use with the Arduino and other MCUs. The circuit uses two TIP120 Darlington Transistors, two 220 ohm resistors and a 12 volt DPDT relay, parts easily obtainable at any Radio Shack. This design supports PWM for variable speed control, handles loads up to 5 amps, and is controlled using just two MCU pins for “enable” and “direction”.

Via Instructables.

Datasheet tips for newbies (and everyone else)

Circuitguy has published this guide entitled Datasheets (Don’t) Lie on his website. Its intended to show newbies how easy it is to mistake a component’s capabilities when you fail to consider all relevant information on the datasheet. Something those new, and not so new to the hobby, have to keep in mind.

TOOLS: Soldering supplies

Our favorite tools have a new home on the wiki. Each week we’ll muse about one of them. Have your own tool review? We’ll post that too!

This week’s tool is a collection of stuff: the things we use for soldering. We regularly work with surface mount (SMD) parts down to 0603, but it doesn’t take expensive or exotic tools:

  • Solder. We use 60/40 tin/lead solder, it is the only way to go for hand prototyping. It makes recycling parts with hot-air much easier than lead-free solders, which is probably a net positive for the environment. Most solder has some flux, ours lists 2%, but it is never enough, use more! We had been using a 0.7mm wide solder, but recently found a 0.5mm reel. The 0.5mm solder is thin enough to solder SSOP and QFP pins individually, which means there’s less excess solder that needs to be mopped up with wick.
  • Flux. Flux helps solder flow better, and keeps it out of places you don’t want it. Don’t even try to solder without copious amounts of this magic goo. Our syringe of flux came from a surplus store. According to the label it expired in 1991, but it still works great!
  • Solder wick. There are almost always solder bridges between the tiny pins on hand-soldered SMD chips. Apply a little extra flux to the pins and mop up the excess solder with wick. Wick is the trick to soldering SMD without attending to each pin individually – glob down a bunch of solder and soak up the excess with wick, enough remains behind to connect the part to the PCB.
  • A sponge. An iron covered with soldering gunk doesn’t conduct heat well. A clean iron is much easier and faster to work with. We use a giant natural fiber sponge moistened with a bit of water to clean the iron. We give it a quick swipe whenever the iron looks dirty. Go for a big one, the tiny sponge in the iron holder is totally insufficient.
  • Tweezers. We use ’00’ size surgical tweezers to hold SMD parts while soldering. The pointier the better. These were 50 cents at a surplus store.
  • Jewelers loupe. A loupe magnifier is a must for inspecting SMD connections. It doesn’t need to be expensive. We won this loupe in Hacked Gadget’s Halloween contest a few years ago.
  • Sticky tack/poster tack/Blu-Tack. This is a sticky putty often used to hang posters in student dorms. We use it like many people use a helping hand. It can hold a board steady and keep parts in place. We also put it on the end of a pencil for a simple vacuum-lifter alternative. Also used heavily in the photo studio.
  • A bright desk lamp. The importance of a bright light cannot be understated, especially for surface mount soldering. The smaller it is, the harder is is to see in the dark.
  • Soldering stations and Storage are within reach.

Board stuffing is an art. Nobody does it the same. What’s in your prototype building arsenal?

There’s more tools too.

Free Bus Blaster v2 PCB via Twitter: RT @dangerousproto

This week we’re trying a new PCB giveaway via Twitter and Facebook. The first few people who retweet the title of this post (auto-posted to Twitter) get free PCBs. This is our first test, apologies all around if the title gets smashed or something goes wrong.

Get a Bus Blaster v2 for $34.95 only at Seeed Studio. Hurry, the first batch is nearly gone!

Continue reading “Free Bus Blaster v2 PCB via Twitter: RT @dangerousproto”