I know - COM ports are quite obsolete, it is still used in many embedded projects. This one is a simple serially controlled I/O board with 29 lines that can be configured to control anything like from stepper motors, relays and other automation appliances.

The board constructed around z8 microcontroller which is quire rare in embedded projects. Despite of 29 I/O lines serial I/O board has some special features like programmable pulse generator, incremental encoder switch input, 3 counter registers, I/O port memory registers. Each I/O line is LED monitored. To make control easier there is a Visual Basic Program Template available where you can set up easy interface to access all board features.

Bipolar stepper motors are common in printers. They are different from unipolar steppers. Bipolar steppers usually have four wires (while unipolar 5). Bipolar stepper motors can be driven by using H-bridge circuit like SN754410 from Texas Instruments.

One SN754410 IC can drive single bipolar stepper motor. In this example you may see two of them, so each motor is controlled via separate H-bridge IC. Whole circuit is built around Basic Stamp BX-24 which can be programmed by using Basic language. Sample source code is available for testing.

Are you feeling afraid or nervous when you find yourself getting lost in a place you have never been before? Do not let this embarrassment situation happen to you again!

You can easily overcome the above manner if you have an Open GPS Tracker. You must wondered, any special features for this GPS tracker. Well, GPS tracker is a small and smart device that plugs into a $20 prepaid mobile phone. It’s consistently respond to the text messages and even your recently location by Google Maps or Wikimapia.

The three main components need for GPS tracker:

• Tyco Electronics A1035D GPS module
• Motorola C168i AT&T GoPhone prepaid mobile phone
• Atmel ATTINY84-20PU AVR microcontroller

Another good news is the phone is currently available FREE, that is mean you can get the phone without any contract on it. If you want to know more how to get it, then you need to check out the ‘forum‘ for detail before May 10! You can get relief and no more ‘hide and seek’ with this GPS tracker.

This is something interesting and may engage you for some time. This project is so called Rhythm Ring which actually is a musical device that can play rhythms and beat patterns by touching sensors with fingers or metal ball bearings. Each sound is lead by bright LEDs that makes effect even more attractive.

When the device is turned on, it begins at a pre-defined position on the circle and sweeps along the tracks in a circular motion. As it sweeps around the circle, it keeps track of the current position along the circumference of the circle. In the center of the board, there are 32 green LEDs arranged in a circle with only one of the LEDs lit at a time, showing the current position. Sequencer has speed control buttons where you can change sweep speed and this way speed up the rhythm. Project very well described (students have to do this) but once made this thing may keep you busy for several hours.

A new bunch of Cornell University student projects 2008 have shown up. One of the projects is a device that is capable to measure various AC power parameters in real time. These include:

• Real power
• Apparent power
• Power factor
• RMS Voltage
• RMS Current
• Frequency
• Energy usage (Kilowatt-Hours)

With C# front end application people can monitor parameters in convenient graphs where you can see energy usage and other listed parameters. Despite measurements device can also be switched on/off remotely by using solid state relay and even can be set to turn the power off if pre-set wattage limits are reached. Device is controlled by Atmega32 microcontroller which reads AC data via internal ADC. The rest is left to AVR math, where mostly Floating point calculations are made. PowerBox communicates with PC graphing and control application via UART port. As a result power measurements are quite precise. Calculated error reaches about 2.57% (~1W), what I think is very good results.