Shawon M. Shahryiar @ embedded-lab.com writes:
In embedded systems, oftentimes it is needed to generate analog outputs from a microcontroller. Examples of such include, generating audio tones, voice, music, smooth continuous waveforms, function generators, voltage reference generators, etc. Traditionally in such cases the most common techniques applied are based on Pulse Width Modulation (PWM), resistor networks and external Digital-to-Analog Converter (DAC) chips like MCP4921. The aforementioned techniques have different individual limitations and moreover require external hardware interfacing, adding complexities and extra cost to projects. XMega micros are equipped with 12 bit fast DACs apart from PWM blocks and again it proves itself to be a very versatile family of microcontrollers. In this post we will have a look into this block.
XMega DAC - [Link]
Jason Bowling writes:
Over the last year I’ve been working towards an underwater sonar system for ROVs and surface boats. In order to learn the basic signal processing required to detect the echoes, I initially got a simple sonar working in air with a desktop conferencing USB speaker/mic running on Windows. A writeup, including source, is here. That article describes the algorithms used in detail and would be a good read if you want the details of how this works.
The next logical step seemed to be to get it working on a microcontroller. There are plenty of low cost ultrasonic sonar modules available that work really well in air, but the idea was to work towards getting a sonar that worked in water. There are currently no low cost sonar modules for hobby use in water.
Audible Frequency Chirp Sonar with the Stellaris Launchpad - [Link]
Joe @ hobbyelectronics.net:
Here you will find complete construction details including circuit diagrams, PCB layouts and PIC firmware (and the source code). The code was written in Proton PIC BASIC but the good news is that there is now a free version of this compiler available for download; AMICUS18.
PIC Digital Thermometer & Clock - [Link]
ARM PRO MINI is a small barebone open source ARM M0 microcontroller board that is great for quick prototyping and as a starting point for your own ARM based custom designs. It was designed and named after the venerable Arduino Pro Mini and it is an excellent stepping stone for makers and hobbyists ‘graduating’ from Arduino to the ARM architecture.
ARM PRO MINI - [Link]
Ralph Doncaster writes:
Since the release of V-USB, dozens of projects have been made that allow an AVR to communicate over USB. USB data signals are supposed to be in the range of 2.8 to 3.6V, so there are two recommended ways to have an AVR output the correct voltage. One is to supply the AVR with 3.3V power, and the other is to use 5V power but clip the USB data signal using zener diodes. Most implementations of V-USB, like USBasp, use the zener diodes. I’ll explain why using a 3.3V supply should be the preferred method.
USB interfacing for AVR microcontrollers - [Link]
by Joe @ hobbyelectronics.net:
This project was built to monitor the temperature of one of our computer rooms at work that has rather temperamental air-conditioning. The maximum temperature can be set, and if this is exceeded an alarm is activated.The unit gives a continuous display of current temperature and it’s possible for the constructor to change the device program firmware or display board.
LED display Over Temperature Alarm - [Link]
by Joonas Pihlajamaa @ codeandlife.com:
Today’s post is something I’ve prepared for a long time. Hardware-wise it’s a simple thing – ATtiny45 emulating a PS/2 device, sending a keypress when three knocks are detected in the attached piezoelectric sensor (or piezo buzzer as they are also called). But if your computer can boot on PS/2 keyboard input and you have your computer stowed somewhere hard to reach (or just want to impress your friends), it’s a pretty neat little gadget! Here’s a video of it in action:
Turning PC On with a Knock using ATtiny45 - [Link]
Bob Alexander of Galactic Studios made this bluetooth serial monitor for embedded microcontroller projects, the Blueprintf:
One way of debugging microcontroller-based projects is to send messages out the UART serial port. Then, a UART-to-USB interface can feed the messages into your PC for display. But I wanted a small, portable device for viewing serial data without a PC, and I wanted it to use my cell phone or tablet for its display.
There are a few advantages to this. First, I don’t always have my PC nearby; maybe the project worked fine on my workbench, but doesn’t work “in the field” where I don’t have a PC handy. Second, the UART-to-USB interface sometimes hangs, especially if there are glitches from the system under test (SUT). Finally, sometimes I just don’t want to string the wires from the embedded system to my PC
Blueprintf – a bluetooth serial monitor - [Link]
by Alan @ kalshagar.wikispaces.com:
I found those beautiful vintage IV9 & IV16 tubes and I had to use them, clock being the perfect candidate. I made already mutliple others based on what was supposed to be a WordClock (hence the project name) only, but became more diversified. I did also a first test with a chainable 5cm x 5cm tube board, this is a 5cm x 10cm dual board improved version.
When I made this project and designed it the idea I had was of course the design (very important) but also reusability and pragmaticallity regarding the components used. What I mean by the latest is that you never really know what component you’ll have at hand, depends on your provider, the component availability, it’s price, or even the package DIP or SMD. Hence the board can work with 3 different type of RTC clocks: just use your favorite or the one in your shelf stock. Personally I love the Maxims DS3231 and DS3234 which are temperature compensated (to a fantastic extend for the DS3234), and both are accessed through different protocols: SPI for the DS3234 and TWI for DS3231. There’s also the EPSON RTC4543 for those living in Japan like me. So again depending of what else you need to wire, choose your poison: all the pins of the MCU are accessible and there’s even a small zone for some DIP components.
The top board uses 74HC595 for maintaining the displayed digits: they come very cheap but I didn’t want to be stuck to the DIP or SMD model (having both in stock), so the board can use any of the two. Same goes with the current limiter resistors: SMD, through hole or even resistor array, your pick. And of course there’s a SMD or DIP led footprint under each tube for the blingbling! (single color, not RGB led)
IV9 & IV16 tube numitron clock - [Link]
This project was made to fill in the lack of electronic systems out there. Guitars have the gTar, pianos have the roll-up version, but there isn’t really a well known electronic replacement for the traditionally expensive and loud drum sets. The system can further be downsized, perhaps to wrist-strap form, as the only necessary components per “drum stick” is a flex sensor and a microphone, components that total less than $5. We plan to develop this from its prototype form into a more marketable product. Hone your drum skills outside of band practice at a fraction of the price. Do it in the comfort of your home without disturbing the neighbors.
Cheap and modular drum system - [Link]