App note: Operational amplifier applications using 8-Bit PIC microcontrollers

in app notes by DP | 0 comments


Operational amplifier applications using 8-Bit PIC microcontrollers (PDF!) from Microchip:

This document aims at uncovering some of the more important parameters of the op amp and the significance in certain applications. Specific examples and case studies of applications using the on-chip op amp of the PIC16F families of microcontrollers will be discussed. A comparison of the characteristics of the op amp on PIC16F will be done with the stand-alone op amps like MCP602 and TL082.

DirtyPCBs two layer ENIG PCB closeups

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DirtyPCBs two layer ENIG PCB review by manis404:

The standard service is $14 for 10 boards. You can have the pads ENIG finished for $15 more, which brings the total cost to $29 for 10 boards, shipped. It is still an excellent deal. The quality is excellent too, as the closeups below illustrate.

See more closeup photos at the io page.

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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Raspberry Pi Videolooper

in R-Pi by DP | 0 comments


Steven Hickson writes:

Introducing videolooper 3.0! This image is compatible with the A,B,B+, and B 2 versions.
I have a brand new version of the Raspberry Pi Videolooper that is compatible with the new B V2 and has a bunch of new features that streamline it for easy use.
It can now loop one video seamlessly (without audio though) thanks to a solution from the talented individual over at

Source code available on Github.

More details at Steven’s blog.

Towards a simple solder-paste extruder

in DIY, tools by DP | 0 comments


Peter wrote an article detailing his prototype solder-paste extruder:

The prototype that I put together is more of a sketch in hardware to help me appreciate the issues of paste extrusion, and help hammer out a design. Instead of using a plunger, I’ve used a very long lead screw that acts as the plunger, and has a gear atop with a captive nut to transfer force. The gear is driven by a Parallax continuous rotation servo, which I thought I’d try given that it simplifies the design by having an integrated gear box (which gives it lots of torque), and it can be directly driven by a microcontroller rather than requiring a separate stepper driver.

More details at Tricorder Project.

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Using RFM69CW instead of RFM12B

in wireless by DP | 0 comments


Martin writes:

The rumors for RFM12B’s end-of-life two years ago seem to have been highly exaggerated now and the popular RF module is still available in abundance. HopeRF has introduced a pin-compatible upgrade, the RFM69CW. The module itself offers improved sensitivity and range compared to the RFM12B (+30%) at the cost of increased power consumption, making it probably a good choice for the receiving end (RFM2Pi), and probably less suited for low power battery operated nodes. The new module supports RSSI for those interested in measuring it.
The new module is more power hungry, and simply replacing a RFM12B on the RFM2Pi v2 or a Funky v3 with it didn’t work; The boards browned out so I had to swap C4 and C7 on the RFM2Pi with 10uF caps and populate the 0805 10uF on Funky v3’s boost regulator circuitry to get it to work. I’ll ship the boards with these refinements from now on so that they are compatible with both the RFM12B and RFM69CW.

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New Energia version available

in MSP430, open source, software by DP | 0 comments



The Energia team announces the availability of version 0101E0015:

The Energia team is very happy to announce the release of Energia 15. This release aside from bug fixes adds support for the new Texas Instruments ARM Cortex M4F based MSP432 LaunchPad. This time around it’s a bit different though. The MSP432 Wiring/Energia framework is based on TI-RTOS. What does this mean? Basing the MSP432 implementation on TI-RTOS takes the Wiring / Energia framework to a whole new level. With this new feature you will be able to run multiple Sketches in parallel. Yes, in parallel! How awesome is that?!
The example we like to use is the problem of blinking multiple LED’s at a different rate. Easy enough you would think? Now imagine what that Sketch would look like. Not so easy huh? Now imagine that you have multiple tabs in Energia with their own setup/loop that run in parallel (Sketches). You can now have multiple tabs each running their own blinky Sketch as a task under TI-RTOS. This is just a simple example. Imagine that you can have multiple tabs doing different things like posting to the internet on one tab while reading sensor date on the other and printing Serial data on yet another tab. All in parallel. These are some ways to use Energia MT that we came up with. We would love to see and hear about what you can come up with! With this release, Energia MT is supported on the MSP432 but the following releases will support the Energia MT for CC3200, TivaC and MSP430 LaunchPads. Learn more about multitasking @ Energia MT

Downloads are available for Linux, Mac OSX and Windows.


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.

Continue reading →

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

TI releases the MSP432 microcontroller

in ARM, MSP430 by DP | 2 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 , , | 2 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.

Continue reading →

#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.

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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 | 72 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:

Continue reading →

Posted in Free PCBs | Tagged | 72 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