Michał posted his DIY USB Infrared Toy:
I’ve redesigned IR Toy’s v2 board a bit and managed to build it on my own and it works perfectly!
I have decoded my Medion’s radio remote control codes via the WinLIRC
Via the forum.
You can get IR Toy v2 for $22.05, including world wide shipping.
Michael Ossmann, co-developer of the HackRF open source SDR platform, writes reminding us that the deadline for student’s entries for the Google Summer of Code 2014 is fast approaching.
If you or someone you know is a college student who would like to spend
the summer getting paid to work on open source source software, I hope
you are aware of Google Summer of Code.Right now is the time for students to register (less than six days remain) and submit proposals.
GNU Radio, one of my favorite open source software projects, is a
mentoring organization for GSoC again this year. I encourage you to
take a look at the project ideas page and see if anything looks
interesting to you. In particular, Jared Boone of ShareBrained Technology (and significant Great Scott Gadgets contributor) has an exciting idea posted there for some software that I think would greatly improve the process of analysis and reverse engineering radio signals.I don’t have any ideas posted there, but I am open to being a mentor
through GNU Radio. If you have a project idea that you think I would
like and that would benefit the GNU Radio community, feel free to run it
by me.Good luck and happy hacking!
Via the contact form.
Kerry Wong writes:
I was doing a project that needed a driver for hard disk spindle motors. While I could use a microcontroller to generate the required driving waveform sequence, keeping the waveform in sync with the motor rotation is actually quite tricky especially at higher rotation speeds. To ensure the correct timing sequence, a back-EMF controller is required for these sensorless three-phase BLDC motors.
Back-EMF BLDC drivers can be implemented using microcontrollers as well (Microchip’s AN1083 describes this approach in detail), but there is quite some complexity to it. So I ended up lokking for dedicated three-phase BLDC motor drivers.After some research, I found two chips that seemed to be able to fulfill my needs. One chip is Taxes Instruments‘ DRV11873, and the other is Microchip‘s MTD6501G. Both chips are very easy to use and are decently priced. TI’s DRV11873 has more features compared to Microchip’s MTG6501G…
joeforker posted an update on his ATtiny LED driver for an RC car we covered previously:
This board delivers 100mA through 2 series-wired LEDs like a champ, powered by a 2S LiPo. Night drives are looking bright. The glaringly bright uncomfortable-coming-straight-towards-you high beam look has been achieved. :-)
As usual, mistakes were made. The through hole components fit for once, but I got the transistor footprint wrong and had to mount the BJTs upside down on the board to swap the emitter and base; the ATtiny was too wide, so I had to bend its leads under itself to make it fit; and worst of all I got the voltage regulator footprint wrong – bzzt! Removed the reg, and the rest works fine. This version will get used without the micro just for the voltage regulator circuit. On to revision C…
The trimpot sets the current between approximately 190mA – 20mA.
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:
Some stuff:
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.
NsN writes:
A while ago I needed some small value resistors as current shunts and I started wondering about the feasibility of using traces as resistors.
There are many theoretical reasons as to why copper traces make bad shunt resistors, but I found surprisingly little practical data.The traces are (from left to right):
– 20 mil wide, 1221 mil long, should be ~30mOhms
– 6 mil wide, 611 mil long, ~50mOhms
– 12 mil wide 1221 mil long, 50 mOhms
– 6 mil wide 1221 mil long, 100 mOhms
Via the forum.
asd has written an article on interfacing Adafruit 7-segment Backpack with Bus Pirate
Bus pirate doesn’t do much by itself but needs some accompanying chip talk to. I got my hands on 7-segment display from Adafruit which has HT16K33 controller on it. HT16K33 chip is accessed via i2c protocol so it is good candidate to learn about i2c.
In this blog post I briefly show how to display “1 2 3 4” on this display using bus pirate.
Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.
Carl informs us that the Hackshed crew has added a tutorial on building a 4-bit binary adder in CPLD as part of their ongoing CPLD beginner’s guide.
Via the contact form.
EverLost shared his color wordclock in the project log forum:
Display: It is now 2:45pm (Simulated, the RTC part is still WIP…)
I am always fascinated with exotic clocks. You may have came across a DIY word clock before (if not, google it). This is my own flavor of word clock.
Color, Traditional Chinese character, with a reflective panel. Also with temperature & humidity display. Precision: 5min, with 4-LED dots at the bottom to indicate +0~+4 min.
Via the forum.
Bus Pirate v4 is back in stock at Seeed Studio. The Bus Pirate is an open source hacker multi-tool that talks to electronic stuff. It’s got a bunch of features an intrepid hacker might need to prototype their next project.
You can get a Bus Pirate v4 for $40, including worldwide shipping.
An AVR ATtiny HVSP fuse resetter by SimpleAVR
- reads device signature and hi-low fuses for hi-voltage serial programmable attinys
- reset hi-low fuses to factory default on target devices
- layout to drop-on attiny13, attiny25/45/85 8 pin devices targets
- attiny24/44/84 targets needs additional breadboard and jumper wires
- standalone operations, fuses values show on 7 segment display
- cannot reset fuse for attiny2313 and atmega devices as they requires hi-voltage parallel programming
Via the comments.
Weiss has written up documentation on his Stepper motor controller:
The reason for this project was my frustration over how much it takes to just test a simple stepper motor. To test a stepper motor you usually need some kind of MCU most likely a Arduino, your breadboard, cables, some kind of driver and other components. When you got all that assembled you still need to write and upload some code to run the driver, but before you can do that you also need to find your USB cable and if the code doesn’t work you have to debug it. All this can easily take an hour but with the Easy Stepper you just plug in your stepper motor and whatever power supply you have and you are ready to go.
Via the forum.
A great app note from NXP on cascading multiple LCD driver to work as one large display.
This application note aims to assist designers using NXP LCD segment drivers in making a cascaded design.
Cascading means combining more than one LCD driver in a design in such a way that makes them appear to the rest of the application – especially to the microcontroller and the display – as one larger LCD driver capable of driving a larger display than the individual LCD drivers are able to. Depending on which devices are cascaded, cascading can be easy and straight forward on the one hand, or need some attention to details on the other hand in order to achieve a properly working set-up.
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:
Hook up your LPC microcontrollers using USB full-speed connectivity using these guidelines from NXP app note
Full-speed USB operates at 12 Mb/s, and although this is not a high data rate, observing some basic rules or guidelines will usually guarantee successful operation.
This application note highlights some of the more important issues that you need to be aware of for a typical full-speed USB application.
Another app note from Micrel the MIC4826/7 Electroluminescent (EL) lamp drivers and designing with EL lamps (PDF!):
The design of an EL lamp circuit begins with the selection of
a lamp. A typical lamp will exhibit a capacitance on the order
of 2nF to 3.5nF per square inch. When a high voltage AC
signal is applied across the electrodes of an EL lamp, an
electric field is generated across the plates of the lamp. This
electric field excites the phosphor atoms to a higher energy
state. When the electric field is removed, the atoms fall back
to a lower energy state, emitting photons as visible light. The
wavelength of the emitted light is determined by the type of
phosphor used and the frequency of the excitation voltage.
Figure 1 shows a typical bridge configuration that is applied
to the EL electrodes to generate the AC signal. Typical AC
voltages applied to the EL lamp are 50V to 250 VPK-PK, with
a frequency of 50Hz to 1KHz.
An application note from Micrel: Fan health monitoring and the MIC502 (PDF!)
This section presents a fan monitoring circuit that can be used in conventional MIC502-based circuits employing pulse-width modulation (PWM) fan speed control. The circuit relies on detecting motor commutation to indicate fan operation and does not require a three wire fan with a tachometer output.
If you’re new to RF hacking you may have heard the term “replay attack” and wondered what it takes to implement one. In this academic presentation Practicing a Record-and-Replay System on USRP a group of researchers from the Shenzhen Key Lab of Advanced Communications and Information Processing and Shenzhen University, give a succinct and practical explanation of just how easy these attacks are. While this paper uses the costly USRP from Ettus, we found this attack just as effective using Michael Ossmann’s reasonably priced open source HackRF transceiver.
Essentially, with GNU Radio installed on your Linux machine and a HackRF attached you can easily record a chunk of RF spectrum to a file and later replay this file as the input to a transmitter (“sink”) block to exactly recreate the signal conditions over the air. The Shenzhen research paper demonstrates how to use this to replay FM broadcast signals as well as GPS. (We verified this works with a garage door opener of our own, one that did not use rolling-code security.) Good explanation of a practical RF hacking technique.
cmardone made this 18f2550 minimal board v2.0:
It was made to simplify breadboard connections for a 18f2550 pic micro.
Features:
- improved Silkscreen ART including a polinesian MOAI :)
- smd 1206 components , more simple to solder
- 1 smd led
- mini usb conector
- reset pads
- mclr resistor
Via the forum.
Scott Harden writes:
I came across the need for a quick and dirty display to show a 4 digit number from a microcontroller. The right way to do this would be to use a microcontroller in combination with a collection of transistors and current limiting resistors, or even a dedicated 7-segment LED driver IC. The wrong way to do this is to wire LEDs directly to microcontroller IO pins to source and sink current way out of spec of the microcontroller… and that’s exactly what I did! With no current limiting resistors, the AVR is sourcing and sinking current potentially far out of spec for the chip. But, heck, it works! With 2 components (just a microcontroller and a 4 digit, 7-segment LED display) and a piece of ribbon cable, I made something that used to be a nightmare to construct (check out this post from 3 years ago when I accomplished the same thing with a rats nest of wires – it was so much work that I never built one again!) The hacked-together method I show today might not be up to spec for medical grade equipment, but it sure works for my test rig application, and it’s easy and cheap to accomplish… as long as you don’t mind breaking some electrical engineering rules…
