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Using FreeRTOS kernel in AVR projects

FreeRTOS is known as Real-Time Operating System. It would probably be too dare to call it real-time-os, preferably a real-time scheduler where applications can be split into independent tasks that share full processor resources by switching them rapidly. It. It looks like all functions are executed in parallel. This feature is called multitasking. There are many debates on using RTOS on AVR microcontrollers as they are arguably too small for the running scheduler. The main limitation is a small amount of ram and increased power usage. If you are going to use lots of tasks in the application, you will probably run out of RAM used for saving context when switching between tasks. Consider FreeRTOS only if you use larger scale AVRs like Atmega128 or Atmega256. Surely you can find smaller schedulers that are specially designed for smaller microcontrollers, even tiny series. On the other hand, if you master FreeRTOS, it can be used with multiple microcontrollers like ARM Cortex, PIC, and various compilers, including IAR, GCC, and Keil Rowley, Attolic. And the main reason to keep an eye on it – it is free. Probably it would take lots of time and space to go through RTOS theory. Some…

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Getting hands on Arduino Ethernet Shield

Probably everyone knows Arduino and perhaps using it. This development platform is worth its popularity. Probably the best thing about it is open-source ideology. Indeed it is an excellent development platform that includes software and hardware solutions where even non-electronics guru can master great projects. In a few years, Arduino has grown in a great community around the world. And that is great – this means that you have access to endless resources, endless project ideas and lots of members willing to help if you are stuck with something. All the necessary information you can always find in https://www.arduino.cc/. OK, enough of talkies. Let’s see what we have here. Thanks to SparkFun electronics, Arduino Duemilanove stands on my table fully assembled and ready to work. I decided to give a try on Arduino Ethernet shield based on Wiznet W5100 chip. It has a library, so you don’t need to think of details how Ethernet chip is controlled. Few lines and you have some info in your favorite browser.

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Temperature sensor with time and date display on graphical LCD

Some time ago, I built a prototyping board with a graphical LCD. It has served for various small projects and prototypes. I had a spare temperature sensor DS18B20 and decided to put on a simple temperature display project. GLCD board is equipped with an Atmega32 microcontroller running at 16MHz. DS18B20 sensor is connected to port D pin 6. LED connected to PD3 is used for indicating EEPROM write activity. The device is navigated with a rotary encoder. It is connected to MCU as follows (more about interfacing rotary encoder here):

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Running TX433 and RX433 RF modules with AVR microcontrollers

Sometimes in embedded design, you may want to go wireless. Maybe you will want to log readings of remotely placed sensors, or build a remote control for a robot or design an alarm system. Radio communications between two AVR microcontrollers can be easily set up with specialized modules. Let us try to run very well-known RF modules TX433 and RX433 (or similar) that can be found almost in every electronics shop. The pair of them cost less than 15 bucks. Transmitter and receiver modules are tuned together to work correctly at the exact 433.92MHz. The transmitter can be powered from a 3 to 12V power supply while the receiver accepts 5V. The 5V is standard for AVR microcontrollers, ideal for 5V devices. Modules do not require additional components – apply power and connect a single data line to transmit data.

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New project batch from Cornell University ECE 4760

It’s been a regular tradition every spring to check out on what’s new in Cornell University ECE 4760 final microcontroller projects. This year isn’t an exception. It seems that they started a 2010 list on new great AVR ATmega644 projects. List is still building up but there already is a 20 project list with projects like Human Tetris, Glove Midi Controller, Talking Voltmeter and other. All projects are compiled with WinAVR/GCC tools – so everyone can take a glance and give a try. It’s a great list of projects starting from 1999 so there are tons of great interfacing examples, code snippets and even ideas for your new project. Keep eye on that lists as there are more to come (it always reaches about 40). Way to go ECE 4760!

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Sticky Light – The Art of Pure Light Interaction

People always say that it’s impossible to catch a light, as the light moving in a very high speed. However, if you’re giving the opportunity to grab and hold the laser light in your palms, would you mind to give it a shot? As you can see on the above picture, a person is holding the red laser light inside his/her hands. Theoretically, it’s a laser spot bounces on a figure being drawn on paper and trying to escape the labyrinth of lines. No camera or projector is used in the experiment. The Sticky Light proposes an experience and allows the users to touch and interact with a beam of pure light. It even fun, when you can play the classic PONG game with this Sticky Light all with your bare hands!

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MattsOffice – The Wonderful Home Automation via Twitter!

How long you’ve used the internet? Well, if you’re still a newbie, then you might never hear about Twitter before, but for those people who have been an internet users for couple of years, they are very familiar with the social networks, such as Facebook, Myspace and Twitter. By the way, as one of the engineer who frequently surfs the internet, Matthew Morey, had invented the smart “MattsOffice”, which is a home automation via Twitter. Morey himself is a big fan of Twitter. He always wants to build a home automation via Twitter that allows him to have the connection through various types of household appliances, such as personal PC, iphone, GPS and much more. According to Morey, there’s one thing that lacking in most of the devices, which is the 2-way communication between Twitter and the device. Normally, you’re able to send an update to Twitter, but are never performing an action based on a Twitter message! However, Morey had found the solution, and applied it on the MattsOffice. He mentioned that the MattsOffice is a perfect device; which is possible for you to send a command by placing a keyword in a @reply message. Let’s say if you…

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The Powerful R/C Steam Turbine Tank

Are you having the guts to play with fire? Hmm…, if you don’t mind to look by other like a freak and would do anything to stand out from the crowd, then you might want to build this powerful R/C steam turbine tank. This R/C steam turbine tank is a very instructable project made by crabfu. Actually, it built based on an R/C machine that is carrying flammable gas (That’s why we should watch out with it, as you’re playing with fire here). It able to produce extremely high steam pressure, which is capable of causing fire alarm to be responded on it! In order to handle this “hyper fire monster”, you must pay proper attention, or you’ll be suffered with blisters on your finger, or even get your house burnt down instantly!

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Twittjr – The Finest Combination of IBM PCjr and Twitter!

IBM, as one of the world’s largest computer company and system integrator, has been created many different types of computers. Amongst the IBM’s computers, the IBM PCjr is considered the very first attempt of IBM corporate to enter the market for relatively inexpensive educational and home-use personal computers. The IBM PCjr introduced in 1984 and it has a 4.77MHz processor, 128KB of RAM and 360KB floppy disks for storage. If we compared these features to the recently computers, it’s totally outdated! Well, instead of keep putting the unused IBM PCjr in the storeroom, isn’t it better to modify it a little bit and turn it into Twittjr? Did you know that Twittjr is a marvelous system that allows an old IBM PCjr to search the public timeline on Twitter? Ok, you’re wondering, “How the Twittjr works?” Well, let’s say you have a IBm PCjr. First of all, you must hook it to an internet-connected computer. The PCjr is used to call the server and establishes a modem connection, which it uses to send a request for whatever search term the user have entered into the computer. Then, the server uses the Twitter Search API to download the three most recent…

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New series of AVR projects from Cornell

It’s been a tradition to check on new projects from Cornell University ECE 4760 Engineering class. They build cool AVR based projects each year and seems that they are getting more and more advanced. During the last 5 weeks of the semester in ECE 4760, Microcontroller Design, students had to combine sensors, actuators, microcontrollers, and mathematical techniques to build something. So 2009 final end up with whole 39 cool projects that include a 3D mouse, Haptic appointment manager, fart detector, tissue impedance biopsy system and several interesting musical instruments. This year the coding was done using WINAVR GCC and AVRstudio. You can hardly find so many AVR projects in other place that are well researched and described. And this number is growing since 1999. This is a great idea to publish these projects instead of stacking them somewhere in dark place like many universities do. Students do lots of interesting stuff why not sharing these ideas, so others could make things even better. Way to go ECE 4760 class. All projects show a great deal of originality and work. There are over 300 projects on the page.

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