Category Archives: Aggregated

Making something useful for your home with Materia 101

via Arduino Blog

motionbutton

When you become a happy owner of a Materia 101 3d printer, the first days are really important to start experimenting with the right attitude. Understanding quickly how to get what you want from it means becoming aware of the potential applications of the 3d printing technology in your environment.

Last week we published  the tutorial  on  “Getting started with Materia 101″ created by Kristoffer  and kicking off a series of step-by-step guides to explore different topics, softwares and settings for your 3d printer.

Take a look at the second tutorial focused on  fixing things at home: “Making something useful” tutorial shows you how to start from a need, to design and print a solution. It feels great to be able to fix what’s broken!

Interested in getting in touch and showing your experiments? Join Kristoffer on the Arduino forum and give us your feedback.

Next week we are going to post a tutorial on how to create 3d-printed cases for Arduino boards. Stay tuned.

Hashtag: #Materia101

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Join us today for SparkFun Live – The Tweeting Turkey Temperature Timer

via SparkFun Electronics Blog Posts

On today’s episode of SparkFun Live, we’re going to build the tweeting turkey temperature timer! The goal of this project is not necessarily to have you build your own turkey timer, but rather to show you how you can use the new Intel Edison to connect your project with Twitter! The episode starts at 3 p.m. MST. You can find the stream here:

This demo will showcase how to automatically tweet temperature data using the Intel Edison. We will be going over Ubilinux, which is a Linux distribution based on Debian “Wheezy” and will be using python wrapper Twython. Note that while the Edison documentation uses Yocto, we chose to load Ubilinux onto the board instead!

For the purposes of the demo, we created a special Twitter account which you can find here. Hope you’ll join us at 3!

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Join us at the Bett Show 2015

via Raspberry Pi

In my former life as a Computing and ICT teacher and even before that as an ICT Technician, I always looked forward to the Bett Show in London. The Bett Show is the world’s leading learning technology event. Imagine a trade show meets teachers conference and you might have some idea of what it is like. Every year the event is opened by the Education Secretary here in England, followed by keynotes from some of the world’s leading educationalists. The next event’s line-up includes Sir Ken Robinson and Jimmy Wales! Not bad for a free event.

bett15small

As a technician I attended to see what cool new tech was available for teachers, and to see if we could replace any of our current systems with something more efficient and cost effective. As a teacher I attended for much the same reasons, to get my hands on all the cool tech, but also to attend the free talks and workshops in the many areas over the course of four days.

The Raspberry Pi Foundation Education Team at Bett 2014

The Raspberry Pi Foundation Education Team at Bett 2014

Last year the Raspberry Pi education team were hosted by the OCR stand and you can read about what we got up to here.

The next Bett Show takes place this coming January from Wednesday 21st January to Saturday 24th January 2015 at Excel London and we at Raspberry Pi plan to have a presence like never before. We want everyone who attends to be able to experience what it is like to teach, learn and make with Raspberry Pi. To do this we need your help.

We need you! We are looking for members of our wonderful community to help us run workshops, give talks or demos and be a part of sharing what we do with teachers and technicians. Teachers, Raspberry Pi certified educators, digital leaders, technicians, academics, parents, code club mentors, workshop leaders, Raspberry Jam event organisers, or Pi enthusiasts.

Over the course of the four days, we have 20 minute and 50 minute slots to fill on our stand that includes a Raspberry Pi classroom. You can give a talk about how you engage young people with Raspberry Pi or how to setup a Raspberry Jam. You could run a Minecraft Pi or Pibrella workshop. You could bring your code club or group of digital leaders to present what they have done with Raspberry Pi.

To submit your session or sessions for our Bett Show stand for 2015, please complete this form.

Save the date for Arduino Day 2015: Saturday 28th of March

via Arduino Blog

ArduinoDay2014 India

Last year, during the first celebration of Arduino Day more than 240 user groups, makerspaces, hackerspaces, fablabs, schools, studios and educators throughout Europe, North and South America, Asia, Africa and Australia planned activities, workshops, events for a wide range of audiences and skillsets. They celebrated together the open source community gathered around Arduino globally.

Arduino-Day-2015

We are now organizing the second edition of this worldwide anniversary celebrating Arduino community and the makers’ movement. Everyone can participate in the role of organizer or as a participant.
Stay tuned because at the beginning of February we’ll be launching the open call for entries. In the meanwhile check the countdown here http://arduinoday.tv – Hashtag: #ArduinoD15

 

ramanPi: an open source 3D-printable Raman spectrometer

via Raspberry Pi

The 2014 Hackaday Prize offered fabulous prizes for the best exemplars of an open, clearly documented device involving connected electronics. Committed hardware hacker fl@c@ (we understand that’s pronounced “flatcat”) wasn’t in the habit of opening up their work, but had been thinking that perhaps they should, and this seemed the perfect opportunity to give it a go. They decided to make an entry of one of their current works-in-progress, a DIY Raman spectrometer based on a Raspberry Pi. The project, named ramanPi, made it to the final of the contest, and was declared fifth prize winner at the prize announcement in Munich a couple of weeks ago.

ramanPi optics overview

Raman spectroscopy is a molecular identification technique that, like other spectroscopic techniques, works by detecting and analysing the characteristic ways in which substances absorb and emit radiation in various regions of the electromagnetic spectrum. It relies on the phenomenon of Raman scattering, in which a tiny proportion of the light falling on a sample is absorbed and then re-emitted at a different frequency; the shift in frequency is characteristic of the structure of the material, and can be used to identify it.

The ideal molecular identification technique is sensitive (requiring only small quantities of sample), non-destructive of the sample, unambiguous, fast, and cheap; spectroscopic methods perform pretty well against all but the final criterion. This means that fl@c@’s Raman spectrometer, which uses a Raspberry Pi and 3D-printed parts together with readily available off-the-shelf components, removes an obstacle to using a very valuable technique for individuals and organisations lacking a large equipment budget.

The ramanPi uses a remote interface so that it can be viewed and controlled from anywhere. Like conventional Raman spectrometers, it uses a laser as a powerful monochromatic light source; uniquely, however, its design:

[…] is based on an open source concept that side steps the expensive optics normally required for raman spectroscopy. Ordinarily, an expensive notch filter would be used which is cost prohibitive for most average people. My system avoids this cost by using two less expensive edge filters which when combined in the correct manner provide the same benefit as the notch filter…at the minimal cost of a little extra computing time.

Once a cuvette containing the sample to be tested is loaded into the ramanPi, the laser is powered up behind a shutter and the first filter is selected while the cuvette’s temperature is stabilised. Then the shutter is disengaged and the sample exposed to laser light, and scattered light is collected, filtered and passed to a Raspberry Pi camera module for capturing and then analysis. The laser shutter is re-engaged and the process is repeated with the second filter. The Raspberry Pi combines multiple exposures into a single image and carries out further image processing to derive the sample’s Raman spectrum. Finally, the spectrum is compared with spectra in online databases, and any match found is displayed.

fl@c@ says,

I’ve been trying to build up the courage to share my work and ideas with the world because I think it benefits everyone. This project is my first to share, and for it to be featured here [in a Hackaday Prize Hacker bio] […] is really amazing. I appreciate this whole community, I’ve learned a lot from it over the years and I hope to be able to give back and contribute more soon!

We’re very glad fl@c@ did decide to share this – ramanPi is an astonishing first contribution to the open source movement, and something that’s likely to be of interest to schools, chemists, biologists, home brew enthusiasts, people who want to know what’s in their water, businesses, ecologists and the simply curious.

You can read about ramanPi in much more detail, with further videos, diagrams, discussion and build instructions, on its Hackaday project page. We hope that this is far from the last we’ll hear of this project, or of fl@c@!

More Simple Sketches

via SparkFun Electronics Blog Posts

A couple weeks ago, we announced SparkFun “Simple Sketches”. These shorts videos are designed to quickly show you some of our favorite boards and sensors in action. This is far from an in-depth look at these products, but rather to give you a quick visual way to check out a part in action and see if it meets your needs. Today, we’ve got a whole slew of them.

Capacitive Touch Keypad - MPR121

One Wire Digital Temperature Sensor - DS18B20

Temperature Sensor - Waterproof DS18B20

Infrared Thermometer - MLX90614

SparkFun RGB and Gesture Sensor - APDS-9960

Photo Interrupter - GP1A57HRJ00F

Optical Detector / Phototransistor - QRD1114

Humidity Sensor Breakout - HTU21D

Triple Axis Accelerometer Breakout - MMA8452Q

What products would you like to see a “Simple Sketch” for? Let us know in the comments below!

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Direct Digital Synthesis (DDS) Explained by [Bil Herd]

via Hackaday » hardware

One of the mnemonics you may hear thrown around is DDS which stands for Direct Digital Synthesis. DDS can be as simple as taking a digital value — a collection of ones and zeroes — and processing it through a Digital to Analog Converter (DAC) circuit. For example, if the digital source is the output of a counter that counts up to a maximum value and resets then the output of the DAC would be a ramp (analog signal) that increases in voltage until it resets back to its starting voltage.

This concept can be very useful for creating signals for use in a project or as a poor-man’s version of a signal or function generator. With this in mind I set out here to demonstrate some basic waveforms using programmable logic for flexibility, and a small collection of resistors to act as a cheap DAC. In the end I will also demonstrate an off-the-shelf and inexpensive DDS chip that can be used with any of the popular micro-controller boards available that support SPI serial communication.

All of the topics covered in the video are also discussed further after the break.

DDS Demo Hardware
DDS Demo Hardware

I chose to use Programmable Logic (PL) to build the various circuits as it was quick to configure and didn’t require very much construction while being extremely flexible. It also didn’t require any software programming, IDE, target processor board, etc. This might be an interesting project for you if you are interested in learning or exercising some basic Programmable Logic skills, here I use Altera’s free Quartus II Web version and an inexpensive programmer clone. For the first couple of examples I am using a Complex Programmable Logic Device. (CPLD)

Basic Signal Generation

Altera CPLD DDS
Altera CPLD DDS

Creating waveforms can also be done with dedicated logic, for example a CD4060 oscillator/counter can be used instead of the PL counter or also a microcontroller with I/O ports could be used. Note that the microcontroller version does better the more assistance it gets from dedicated peripherals such as a timer or a timer/counter that reloads without waiting for the processor to respond and reset it.

Direct Digital Synthesis (DDS) R/2R Ladder

Here are two waveforms created with a simple counter and resistors organized as an R/2R ladder. As the output of the counter increments in binary, the resulting voltage divider created by the interconnected resistors and outputs creates consistent steps between each of the counts; 256 in this case due to 8 outputs being used. Taking the most significant bit also demonstrates a symmetrical square wave.

Building Different Signals is Easy

If the counter were to count downwards upon reaching its maximum count instead of resetting to zero, then a triangle waveform would be generated. So far that’s three waveforms using just a counter and some resistors.

Triangle Waveform DDS R/2R Ladder with Comparator

On a slightly different topic, using just some I/O lines, an R/2R ladder, and an analog comparator (ala LM339) a basic type of Analog to Digital Converter (ADC) can be made. Don’t misread this, we were talking about going from digital to analog before but now we’re talking about going from analog to digital.

To describe it simply, a processor or digital counter is connected to the R/2R ladder which is connected to the input of an analog comparator. The voltage to be measured is then connected to the other input of the comparator and then the counter proceeds to count up until the R/2R ladder voltage equals or exceeds the voltage being measured. At that time the comparator trips and the equivalent digital value of the analog voltage being measured is represented by the counter value feeding the R/2R ladder.

Assuming that the voltage to be measured is somewhat stable, the process can be repeated to track the voltage as it (slowly) changes or the count can be reversed until the comparator clears and then reverses. This might be useful for measurements such as monitoring a battery voltage level, etc.

While continuing the use of an adjunctive comparator, a simple voltage to frequency converter can be made by having the counter change directions when the comparator trips. This is not a perfect converter (nothing I do is perfect, life and engineering is a compromise) as very notably the amplitude of the triangle waveform changes in amplitude, but a full voltage square wave would be easy to generate.

Basic Principles for Sine Wave Generation

DDS Sinewave
DDS Sinewave

Finally we can create a sinewave through the addition of a look-up-table that contains the appropriate data to approximate a mathematical sine function. A look-up-table (LUT) is simply a piece of memory such as Read Only Memory (ROM) in series with the data, in our case the incrementing counter represents an incrementing address, and the data output is the result of a pre-calculated Sine table.

For this I have switched to a Field Programmable Gate Array (FPGA) which has better internal memory and the ability to initialize the memory with the contents of the Sine table I created for the LUT. In the schematic for the interior of my FPGA the LUT can be seen off to the right just in front of the output pins.

FPGA w LUT
FPGA w LUT

Programming Complex Waveforms

One advantage of a Sine wave created by DDS is that it can be generated at a wide range of frequencies and keep its same shape (low distortion).

Just for fun and to demonstrate something that can done easily with DDS I created a non-symmetrical waveform. Looking carefully you can see two cycles of square wave, two of ramp and then two of sine wave. Any waveform that can be “drawn” in memory can be created this way.

Square-ramp-sine
Square-ramp-sine

Other DDS Hardware Options

And finally, if you need a DDS without the muss and fuss of making it out of components yourself, there is a selection of DDS components available that are low cost and accurate. Shown here is an Analog Devices 9387 in an evaluation board from the manufacturer. It is SPI serial interface driven and so can be connected to most available single board controllers.

DDS Eval AD9837
DDS Eval AD9837

Varying the frequency and phase of a signal by microprocessor control is integral to a DDS system. The software that comes with the evaluation the board shows that two frequencies and two phase offsets can be stored allowing Frequency Shift Keying (FSK) and Phase Shift Keying (PSK) as well as sweeping between two frequencies. This is a useful capability, for example the frequency response of a circuit such as a filter can be observed by sweeping a frequency on the input and then measuring the output on an oscilloscope.

Eval 9837
Eval 9837

Go Deeper

If you want to know more about DDS there is a lot of information available on manufacturer’s websites and the Internet. Advanced topics to search for include embedded sub-modulation and use with phase lock loops to reduce phase noise, up-conversion using multipliers, and other synthesis circuits used in RF telecommunications.


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