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Lab 11: Multiplexing seven segment LED displays

Posted on March 28, 2011 by R-B 54 comments

In Lab 6, we discussed about interfacing a seven segment LED display to a PIC microcontroller. The seven segments were driven individually through separate I/O pins of the microcontroller. If we do just like that then for 4 seven segment LED displays, 28 I/O pins will be required, which is quite a bit of resources and is not affordable by mid-range PIC microcontrollers. That’s why a multiplexing technique is used for driving multiple seven segment displays. This tutorial shows how to multiplex 4 common anode type seven segment LED displays with a PIC16F628A microcontroller.

Multiplexing 4 common anode seven segment LED displays

A new multi-function power supply unit for my Embedded Lab

Posted on March 26, 2011 by R-B 39 comments

One important parameter in embedded system designing is power consumption. This parameter is directly related to the battery lifetime, if the system is to be powered from a battery. In order to determine the power rating of your designed system, you need to know how much current the system draws from the source at a given voltage. While working on my projects, I usually measure current by placing an external ammeter in series with the current’s return path. This is not always convenient to do, and so I thought of making a special power supply unit for my lab that would display both voltage and current information on a LCD screen while prototyping my circuit. This way I can continuously monitor how much power my test circuit is drawing at a specific operating voltage.

Multifunction bench power supply

AVR based remote controlled fan regulator

Posted on March 25, 2011 by R-B 5 comments

This project is from Extreme Electronics that describes an AVR-based (Atmega8) remotely controlled fan regulator. The control commands are received through a DVD player remote control. With three buttons on the remote control, you can turn the fan On and Off and also conotrol the speed. You can also purchase the PCB for this project too.

AVR Fan Regulator Board

DIY power supply for home server computer

Posted on March 24, 2011 by R-B Leave a comment

This project describes a home made power supply for a small server computer. It uses a toroidal power transformer (not the conventional transformer) to step down the mains AC voltage. The advantages of using a Toroidal is it is quiet, efficient and smaller in size. The transformer output is then rectified and capacitive filtered. DC regulation is achieved using PTN78020 for the 12v supply, and PTN78000 for the 5V one.
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evoMouse: Control your computer with hand movement and gestures

Posted on March 24, 2011 by R-B Leave a comment

Celluon presents a new mouse technology (evoMouse) where you can use your finger as a pointer and no more pushing around a physical mouse. You can perform common mouse operations such as control the cursor, click and select, double-click, right-click, drag, draw, hand writing, etc with basic hand gestures.
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