PWM controller for low noise power supplies

rsdio writes:  These parts look promising on paper, but the sample circuit has too many parts for an inexpensive implementation. I’m still sure something can be learned by studying the data sheets.

MAX5975A, MAX5975B Current-Mode PWM Controllers with Frequency Dithering for EMI-Sensitive Power Supplies:

High Efficiency at Light Loads Meets Green Requirements of Next-Generation IP Phones, WLAN, and IEEE 802.3af/at Powered Devices

  • Optimizes power-supply design with a 100kHz to 600kHz switching frequency, trimmed to 5% accuracy
  • Frequency foldback enables high efficiency at light-load operation
  • Well suited for EMI-sensitive power-supply designs
  • Programmable frequency dithering for low-EMI spread-spectrum designs

XBee wireless interface tutorial

Chris from PyroElectro has posted this tutorial on interfacing with XBee.

He writes:

Getting started with XBee can be tricky, even though it shouldn’t be. Here is a drop-dead simple guide to using XBee modules out of the box. The tutorial shows you how to build a wireless interface with XBee modules between two PIC 18LF4520 microcontrollers.

Thanks Chris! Via the contact form.

Free PCB coupon via Facebook comments

Every Friday we give away some extra PCBs via Facebook. The first few people who comment on this at Facebook get a free PCB. More PCBs via Twitter on Tuesday and the blog every Sunday.

This week we’re giving away two PCB codes. Pick your own PCB from the free PCB drawer.

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

  • Free PCB Sunday. The classic. Every week, right here on the blog
  • 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 comments”

Simple LaunchPad DAC


NJC’s MSP430 LaunchPad Blog presents this short tutorial on using DAC with the LaunchPad. He writes:

This post will show you how to generate a periodic analog signal using the LaunchPad and the MSP430G2231. For the sake of simplicity, I stuck to the default DCO value. This will allow us to generate a very clean sine wave at 128Hz. If the DCO is increased to 16MHz and a few other design parameters are changed the maximum frequency can be over 4kHz. Using the MSP430F5510 I was able to generate a crystal clear 32kHz sine wave.

Why would you want to do this? Well, this code can be modified so any arbitrary analog waveform can be generated (reasonably speaking). At the very least you will learn some interesting analog principles if you decide to build this mini-project.

App Note: wireless home security implementing KEELOQ® and PIC®

KEELOQ® is an authentication system designed by Microchip. It’s based on a proprietary, non-linear encryption algorithm that creates a unique transmission on every use, supposedly rendering RF replay attacks useless. The algorithm uses a programmable 64-bit encryption key unique to each device to generate 32-bit hopping code.

In this new app note, Microchip presents a design for a basis wireless home security system. The project implements an HCS200 encoder for the intruder sensor signal encryption, one PIC12C508A PIC® MCU for sensor monitoring and RF signal initiation, HCS515 decoders for decrypting the received intruder sensor signal and a PIC16C77 PIC MCU for base station panel monitoring and control.

Week in (p)review: June 17, 2011

This week was lost to server setup and site migration. Thanks for hanging in there. We’re back now, pushing to Twitter and Facebook too.

Look out for new features and updates. A new mobile forum interface makes it easier to read and post. Many have noticed a substantial speedup with the new server too. Lots of bugs have been fixed, but there’s bound to be a few more.

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:

We’ll be catching up all week, there should be lots of good stuff:

  • The final word on our site outage, and why we’re off the cloud
  • LeafLabs Maple conference call, delayed twice due to site outage
  • 100% open source PIC USB stack is crazy stable. JTR is already updating the IR Toy to make use of the new features
  • Bus Pirate v3.5 is ready, we’re the hold up because we haven’t sent the sales page yet. This will be done this weekend. All pending order will ship Bus Pirate v3.5 (we think)
  • More updated release packages
  • Free PCB Sunday
  • Free PCBs via Twitter on Tuesday
  • Free PCBs via Facebook on Friday
  • Weekly roundup and preview every Friday

What are you hacking this week?

TMP006 IR temperature sensor pictures and tests

Joe posted pictures of the single-chip digital IR temperature sensor covered earlier.

jbeal has measurement tables and first impressions in the forum:

I got the eval kit for the TI TMP006 sensor mentioned here last week. It does seem to be able to detect the presence of my hand (apparently about 37 C), when I place it in front of the sensor and then remove it (so the sensor sees just the surface of my desk, around 25 C). The sensor sits in the open on a flat PCB. I wonder if it would be a bit less noisy if it was semi-enclosed and shielded from stray air currents.

Via the comments.

MSP430 FRAM board – 50% Off coupon

octal writes:  the board cost is $29. Enter this coupon “MSP430_FRAM” (without quotes) and you got it at 50%, shipping fees are still free from TI Store.

The MSP-EXP430FR5739 Experimenter Board is a development platform for the MSP430FR57xx devices. It supports this new generation of MSP430 microcontroller devices with integrated Ferroelectric Random Access Memory (FRAM). The board is compatible with many TI low-power RF wireless evaluation modules such as the CC2520EMK. The Experimenter Board helps designers quickly learn and develop using the new MSP430FR57xx MCUs, which provide the industry’s lowest overall power consumption, fast data read /write and unbeatable memory endurance. The MSP-EXP430FR5739 Experimenter Board can help evaluate and drive development for data logging applications, energy harvesting, wireless sensing, automatic metering infrastructure (AMI) and many others.

Via the forum.

Kinect for Windows SDK beta released

Microsoft has released the beta of their Kinect for Windows SDK.

The Kinect for Windows SDK beta is a programming toolkit for application developers. It enables the academic and enthusiast communities easy access to the capabilities offered by the Microsoft Kinect device connected to computers running the Windows 7 operating system.

The Kinect for Windows SDK beta includes drivers, rich APIs for raw sensor streams and human motion tracking, installation documents, and resource materials. It provides Kinect capabilities to developers who build applications with C++, C#, or Visual Basic by using Microsoft Visual Studio 2010.

You can download the SDK beta here (Windows 7 only.)

Thanks theHoz! Via the contact form.

Gear: Parallax Propeller emulator/debugger

While it’s been around for a while, few users of the Parallax Propeller are aware of of the debugger known as Gear. Gear is an open source Propeller emulator, with support for step through debugging and component plug-ins. It runs under Windows XP and requires .NET 2.0. It does not appear as full featured as ViewPort, but it’s free.

You can download Gear-1.11.0 here.

Joe Grand’s laser range finder

Joe Grand has finished work on his Laser Range Finder (LRF) project. This project, which has been in development in cooperation with Parallax Inc., is now in final beta testing. Check out Joe’s development diary for all the exhaustive details and links to development videos.

Joe reports that after final tweaking is completed, he expects the module should be going into production sometime in July and would be ready for sale through Parallax a few months after that.

Control #twatch from Linux command line

llauren used Netcat to control his #twatch:

I received my #twatch the other day. I found out that the most basic way to speak to the #twatch is using Netcat (nc). Netcat probably comes as standard with most Linux distros and if it doesn’t, then install it. On a Debian-flavour platform (like Ubuntu)

Via the forum.

Continue reading “Control #twatch from Linux command line”

Hacking a PIR RF signal with PIC 12F683

Deepak from Mindfront.net acquired a PIR alarm sensor module which transmitted a digital code over 433 MHz RF to signal an alarm receiver. The problem: he didn’t have the factory receiver. So he set out to sniff the transmitted RF signal using a RCR-433-AS receiver module with the data out fed into an oscilloscope. This allowed him to monitor the digital coded signal pattern and decode it into individual bits.

He took this information and wrote a program for the PIC 12F683 which would read the receiver module’s data output and trigger only when the intended code was received. Source code for this project is available from Mindfront.net under GPL license.

We can imagine some “dangerous” uses for this hack. To pull off an RF signal replay attack it’s theoretically possible to copy the received code pattern then replay in on the appropriate RF frequency using a transmitter module. If your neighbor uses one of these RF PIR sensors in their yard or driveway you could try a 21st century digital version of ringing the doorbell and running from the safety and privacy of your own home.

Free ESC virtual conference June 16, 2011

ESC Silicon Valley is presenting a free virtual conference on June 16, 2011, from 8 AM to 3 PM PT. The lineup includes a fireside chat interview with Steve Wozniak, as well as presentations on Cortex M4 development, Android development, agile software development techniques for embedded systems as well as modern network security protocols for embedded systems.

Register now for this free online event.