Embedded systems that are dealing with DAC require a good voltage references. Despite all voltage references have their nominal values there are specific tolerances that indicates how much values can vary from nominal value. References as a rule are semiconductors that characteristics are effected by temperature.

For instance if we decide to use a 2.5V voltage reference then (zener) diode LM336A-2.5 may be a good choice for this.

These diodes have low temperature coefficient. It can guarantee that voltage will be in range between 2.44 and 2.54 at 25ºC. This precise zener diode has a third lead that can be used to adjust break down voltage. In the following figure you may see diode with potentiometer where breakdown voltage can be adjusted in range of ±120mV: Read the rest of this entry »

Guys from Evil Mad Scientist Laboratories have released 2nd version of their Peggy LED display kit. It is a 25×25 LED display board which is capable to display various LED effects, output text and even animation with individual LED addressing.

This is quite smart construction allowing to drive any number of LEDs (from one to 625). Peggy board has several buttons that can be used to control various actions like games or other effects.  The board itself is nicely designed so it wouldn’t be a shame to use it as a dynamic LED sign, FFT sound grapher,  RSS reader or simply as general purpose giant display. You can order peggy board as a kit or try to build it by yourself as all project files are available for building, hacking or simply analyzing.  [Peggy v2.0]

Probably this programmer cable can be found on every AVR fan website. It very simple and easy to build. You just need few passive components that can be packed inside LPT connector. From my perspective I wouldn’t recommend using this one programmer if you are more serious in microcontroller projects, because it has poor computer port protection. It connects directly to LPT port without precautions. I definitely recommend using similar ISP circuit with buffer IC between LPT and target board.

But let’s don’t pretend like we are very smart. The whole beauty is in its simplicity. This thing does its job perfectly as long as target board power supply is OK. Read the rest of this entry »

It’s been ten years when Cornell University Computer Engineering students were publishing their final embedded projects. I always enjoy browsing over that big list of complete projects. You can get some crazy ideas here but also some good lessons that could be helpful while building your own projects.

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This PCB drill is made of wood and looks really cool. Wouldn’t mind to have one on my table. Design is very unique - it uses various custom made parts, motors from old printers and VCR’s. Author even simulated all design code on a Labcenter’s Proteus VSM.

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As the global fuel price keeps rising like a rocket, it is always a pleasure to find some alternative power supply.

The wind energy can be considered as one of the clean, eco-friendly and free energy. The main problem is natural wind did not always blow at the same speed and this will gradually affected the efficiency by using wind powered generator.

Winds normally blows at intermittent condition, where sometimes the speed is high or low, also sometimes it will eventually changed the direction as well.

For overcome this matter, we can create an Intermittent Wind Powered Generator which it can effectively contribute energy even with intermittent wind.

The working diagrams of intermittent wind powered generator:

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Every time I watch the space invader and those cool space wanderer that landing on the moon and wandered around it, this made me felt excited.

If you never tried to create a house wanderer by yourself believe me, this is fun experience.

What to make one for yourself?

No problem but you needs to prepare these materials first:

• PIC18F6722 Dev Board and CCS compiler as main brain,
• Bend Sensor for feeler whiskers,
• Servo act as a turret wave for better view,
• SRF05 Ultrasonic Sensor for detecting the wanderer movement distance,
• HM55B Compass works as a direction/guide for wanderer,
• L298 Motor Controller to control the two motors,
• Wheel Watcher Module function as odometer (distance measure meter) Read the rest of this entry »

Probably most proper microcontroller programming method is using a bootloader program. Because you don’t need any special programming adapters or special knowledge - you just need to connect standard cable from your PC to target board and run special program on PC which communicates with MCU bootloader program. The idea is simple:

If microcontroller is preconfigured then after reset it starts running not from start memory location which is usually at 0×0000 address, but at some specific location, where usually bootloader lies. Read the rest of this entry »

Open source rocks isn’t it? Here is a new WinAVR 20080411 release available for download. As always new release has lots of tweaks, bug fixes and optimizations. There are new XMEGA series microcontrollers preliminary included in supported device list. So we may have a chance to put hands on these new cool AVR microcontrollers. Here is a list of new things in WinAVR:

• Support of new AVR devices: ATxmega128A1, ATxmega64A1, ATxmega32M1, ATxmega32C1, ATxmega32U4, ATtiny167;
• New GCC4.3.0 compiler;
• New version of AVR-LibC 1.6.2;
• Two new Makefile templates added where one will generate a library instead of an application (Makefile.lib), while another will enable whole program optimization. This seems to be new thing - it will be interesting to experiment with.
• New version of SRecord 1.38;
• New version of SimulAVR 0.1.2.5;
• Removed AVR-Ada (as they say - temporary)-I don’t need it anyway…

Just recompiled my old code - seems to be working fine. So I recommend you to update to newer WinAVR version.

Still struggling with various PCB making technologies and cannot do it right, you should try Photo Etching method which is becoming more and more common among radio amateurs. All materials needed are easily accessed. Probably the hardest part is to obtain UV light source. But you can find tons of sources on the internet how to build one.

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