in Arduino, hacks by DP | 2 comments


Richard Visokey of AD7C made a DDS VFO using AD9850 and an Arduino Uno:

I built a simple VFO for a direct conversion receiver I am putting together. The VFO uses an AD9850 DDS chip to synthesis a nice 1Vp-p sinusoidal wave. I used an Arduino Uno to set the AD9850 frequency, drive an LCD display, and take input from a rotary encoder to set the output frequency.

Project info at AD7C.

Check out the video after the break.

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Posted in Arduino, hacks | Tagged , , | 2 Comments

TI releases the MSP432 microcontroller

in ARM, MSP430 by DP | 3 comments

Introducing MSP432: MSP’s new low-power 32-bit ARM® Cortex®-M4F MCUs

TI is announcing an expanded MSP portfolio including a new family of 32‐bit processors built on the ARM Cortex‐M4F core. The first family includes the MSP432P401x MCUs with 48MHz speed, 1MSPS 14‐bit ADC, up to 256KB flash, up to 64B RAM and low‐power operation of only 95uA/MHz active and 850nA in standby with RTC.

MSP432 FAQ here.

Via 43oh.

Posted in ARM, MSP430 | Tagged , , | 3 Comments

RainCloud Umbrella Minder v2

in DIY, sensors, wireless by DP | 0 comments


Do you always forget your umbrella whenever it rains? No more!  Jeremy Blum shows you how to easily make a RainCloud Umbrella Minder:

The RainCloud is a web-connected smart umbrella holder. Built around the LittleBits Cloud Bit, the RainCloud allows you to tell with a glance if you need to bring your umbrella with you for the day! A 3D-printed stand holds the umbrella, and features a subtle EL-wire pattern that illuminates if rain is imminent. If you’re very forgetful, the RainCloud will even ping your phone to inform you that you’ve left your umbrella behind if you leave home without it on a potentially rainy day.

Check out the video after the break.

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#FreePCB via Twitter to 2 random RTs

in Free PCBs by DP | 1 comment


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.

Posted in Free PCBs | Tagged | 1 Comment

KeySweeper – covert Microsoft wireless keyboard sniffer using Arduino and nRF24L01+

in Arduino, hacks by DP | 3 comments

Samy Kamkar has written an article detailing the build of his KeySweeper project:

KeySweeper is a stealthy Arduino-based device, camouflaged as a functioning USB wall charger, that wirelessly and passively sniffs, decrypts, logs and reports back (over GSM) all keystrokes from any Microsoft wireless keyboard in the vicinity.
All keystrokes are logged online and locally. SMS alerts are sent upon trigger words, usernames or URLs, exposing passwords. If unplugged, KeySweeper continues to operate using its internal battery and auto-recharges upon repowering. A web based tool allows live keystroke monitoring.

Files and source code available at Github.

Project info at Samy’s project site.


Posted in Arduino, hacks | Tagged , , | 3 Comments

Low power magnetic hold and release mechanism

in how-to by DP | 2 comments

This video by Shane Ormonde discusses the low power magnetic hold and release mechanism:

With the inductor and magnet combined, ferrous metal objects can be held without any power indefinitely. To release the metal object the magnetic field holding it up needs to be temporarily cancelled out. This happens by pulsing current through the inductor which generates a magnetic field separate to that of the magnet. These two magnetic fields are of the opposite polarity meaning the inductors field cancels out the magnets field. The inductor only has to be powered long enough for the item to drop which I haven’t measured but its probably somewhere in the hundreds of milliseconds lets say around 100 milliseconds at a guess. This means you can hold an object for potentially a very long time (months, years maybe I dunno!) and expend a relatively small amount of power releasing it compared to if you’d used an electromagnet to hold the thing up which required a constant power source.

Details at Wattnotions.

AVR timer-based one shot explained

in AVR by DP | 0 comments


Josh writes:

Last time, we made one-shot pulses using the AVR’s built in hardware timer module. Today we are going to dive deep into the datasheets to see how this technique is able to coax the normally free-running timer into generating a single pulse. Along the way, we will learn about the low level rules that govern the operation of the timer, and use a trick or two to get around those rules. Read on!…

Project details at Josh’s site.

Posted in AVR | Tagged , , | Leave a comment

App note: Low pin-count LCD interface

in app notes by DP | 0 comments


Back to basic LCD interfacing app note(PDF!) from Silicon Labs.

This application note provides an example interface for a C8051F330 device with an example LCD. First, this application note describes how an LCD works and then describes the two types of LCDs: direct drive and multiplexed drive.  Next, the software interface and structure are explained. Finally, this note describes how to modify the software example to work with other LCDs.

The code accompanying this application note was originally written for C8051F33x devices. The code can also be ported to other devices in the Silicon Labs microcontroller range.

Free PCB Sunday: Pick your PCB

in Free PCBs by DP | 74 comments


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:

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Posted in Free PCBs | Tagged | 74 Comments

App note: Advanced Encryption Standard (AES) implementation on C8051F326/7 devices

in app notes by DP | 0 comments


An AES implementation on Silicon Labs’ C8051F326/7 microcontrollers app note(PDF!)

The Advanced Encryption Standard (AES) is an algorithm used to encrypt and decrypt data for the purposes of protecting the data when it is transmitted electronically. The AES algorithm allows for the use of cipher keys that are 128, 192, or 256 bits long to protect data in 16-byte blocks.

The purpose of this application note is to provide a sample implementation of the AES algorithm for Silicon Labs microcontrollers and to detail the performance of the implementation. The provided example code is intended for
C8051F326/7 devices, but, since the code is not hardware-specific, it can easily be ported to any Silicon Labs microcontroller.

App note: Designing efficient digital up and down converters for narrowband systems

in app notes by DP | 1 comment


An app note (PDF!) from Xilinx on designing efficient digital up and down converters for narrowband systems:

Digital Up Converters (DUC) and Digital Down Converters (DDC) are key components of RF systems in communications, sensing, and imaging. This application note demonstrates how efficient DUC/DDC implementations can be created by leveraging Xilinx® DSP tools and IP portfolio for increased productivity and reduced development time. While previous application notes have provided examples of DUC and DDC implementation in wideband
communications systems, this document concentrates on narrowband systems and the
building block components available to meet the particular requirements of such designs.
Step-by-step guidance is provided on how to perform simulation of narrowband DUC/DDC systems in MATLAB®, how to map functions onto building blocks and IP cores for Xilinx® FPGAs in System Generator software, and how to verify the implementation against the simulation model. Two examples are provided: a multi-carrier GSM system (both DUC and DDC) and a multi-channel MRI receiver (DDC only).

Posted in app notes | Tagged , | 1 Comment

Free PCB coupon via Facebook to 2 random commenters

in Free PCBs by DP | 2 comments

buspiratev383 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.  The coupon code usually go to Facebook ‘Other’ Messages Folder .  More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

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Posted in Free PCBs | Tagged | 2 Comments

Mini stereo SE tube amp

in DIY, hacks by DP | 0 comments

Mini stereo SE tube amp

Gert of KGELABS posted a step by step guide of his DIY small stereo amplifier:

This project started after getting an old schoolproject from a friend. A metal chassis with a single ECL86 tube, a power transformer and a small Muvolett (Amroh) 7044 output transformer. Intrigued by the simplicity of this amplifier I decided to rebuild the amplifier into a small stereo amplifier.

Posted in DIY, hacks | Tagged , | Leave a comment

KF5OBS’ Dirty PCBs review

in by DP | 0 comments


KF5OBS’ first PCB manufacturing run with Dirty PCBs:

So what’s the quality of the board? For $ 33 delivered I naturally didn’t expect much. But I was wrong. First off, I received 12 PCBs. So the Protopack definitely worked in my favor over ordering a guaranteed 10 pack for twice the price. Asides from some minor imperfections on the “J2″ outline, the silk-screen is of very good quality. Even the small text is clearly readable. I’ve often had issues with crappy silk-screen even with “high quality” services so this really impressed me. The vias also look very satisfactory.

Kit assembly 0-30V 0-3A adjustable linear power supply

in DIY by DP | 0 comments

Florin of YourITronics writes, “In this video I am assembling a 0-30V 0-3A Adjustable Linear Power Supply kit. Will it work at first power on? Or will Murphy get me this time? Watch the video and see how I got myself into trouble. I also reverse engineered and got a schematic of this kit which I am showing towards the end of the video.”


Yet another laser oscilloscope

in hacks, oscilloscope by DP | 1 comment


Kerry Wong writes:

You can generate some pretty amazing patterns by shining a laser onto a mirror mounted on a vibrating speaker cone, a lot of people have experimented with this kind of laser show. But how about building a true laser oscilloscope that is capable of displaying signals? In this post, I will show you just that. For those who are impatient, I included a video towards the end.

Project info at Kerry Wong’s site.

Check out the video after the break.

Continue reading →