^{AMATEUR ELECTRONIC PROJECTS}

The projects on this page were produced in the scope of the "Microcontroller Architecture and Applications" and "Integrated Sensors" courses which I took during my Ph.D course session. The first course was focused on three microcontroller families namely PIC, 8051 and Z8. 8051 Development board project was a term-based project aimed to produce a board to emulate different 8051 programs. 8051 projects were written in Assembly Language. The code of the project built using the PIC microcontroller was written in PIC assembly which has a RISC (Reduced Instruction Set Computer) architecture. The latter course includes a wide range of sensors, including mechanical, acoustic, chemical, electrical, biological and etc.

Digital Thermometer and the RS232 Interface to PC

Digital thermometer was built by using the temperature sensor LM35DZ, PIC16F877 microcontroller and MAX232 IC. Temperature measurements can also be viewed on a computer program which can monitor the state of COM ports of a PC. Sample measurement data received through COM2 is being viewed on the SERIAL WATCHER program which is distributed freely on the internet.

8051 Development Board

Since 8051 family of products are used in a wide range of applications including home appliances, warfare industry, automobile industry, robotics&mechatronics, their importance in control applications is increasing remarkably for electro-mechanical applications. This simple board is built for educational purposes to emulate different 8051 programs on different ports of the microcontroller. These applications include the simple led blinking processes, motor control applications for robotics, hydraulics and pnomatic applications, etc.

The code is written simply to communicate with the PC through the serial port. The code written in Assembly Language is burned onto the 8K Flash ROM of an AT89S52 microcontroller. You can download a program (A compiled Intel Hex File) on the RAM MEMORY(6264) and run the code through the microcontroller. Therefore, one can easily emulate programs on this simple board. The steps taken to download and run a simple test program are shown graphically.

Program Start Window



Requesting Hex File To Download



Transfer Operations Starting



The directory of The Test Program is chosen



Download Completed Successfully



Prompts The User Command to Start Running



The program is running and the led is on. See the picture below

The terminal program used to communicate with the board is TERATERM PRO which can easily be downloaded from the internet free of charge.

Vibration Measurement Set-Up

The proposed measurement set-up can be used to accurately measure vibration levels in a wide range of applications. The upper limit of the acceleration level that could be measured by this set-up is 1g(1g=9.807 m/sn2). A built-in conditioning amplifier (B&K 2626) has been used for the amplification and filter purposes of the unwanted noise signals in the measurements. The software has been developed with C programming language.

Elements Used in the Construction of the Measurement Set-Up

• B&K Power Supply Type 2805

• B&K Conditioning Amplifier Type 2626

• B&K Accelerometer Calibrator Type 4291

• B&K Accelerometer 4370 (Transducer with the sensitivity of 83.3 mV/g*) (*g=9.807 m/sn2)
• Precision Rectifier Circuit

• Micro-controller PIC16F877

• 3 4511 BCD to 7 Segment Decoder Ics

• 3 7 Segment Displays

FLOWCHART FOR THE GENERAL PROCEDURE

1.) The accelerometer signals are fed into a built-in amplifier and filter circuit which gives an AC output with peak amplitude of 1V/g (g=9.807 m/sn2)

2.) The main controller element in this project is the micro-controller (PIC16F877) which acquires and processes the electrical vibration signals. In order PIC to receive the voltage which has been produced by the accelerometer, the AC output of the amplifier circuit must be rectified and by the use of a simple RC filter the signal must be converted into a DC signal of approximately the same amplitude. A precision rectifier circuit has been used for this purpose. The schematics and explanation of this rectifier is given below.

The circuit shown above performs full-wave rectification on the input signal, as shown. If you wish the final output to be positive instead of negative, simply reverse the two diodes in the half-wave rectifier section.

The full-wave rectifier depends on the fact that both the half-wave rectifier and the summing amplifier are precision circuits. It operates by producing an inverted half-wave-rectified signal and then adding that signal at double amplitude to the original signal in the summing amplifier. The result is a reversal of the selected polarity of the input signal.

The resistor values shown are reasonable; the resistors themselves must be of high precision in order to keep the rectification process accurate. If for some reason you must build such a circuit with a different set of resistance values, you must maintain the indicated 2:1 resistance ratio, and you must still use precision resistors in order to obtain accurate results.

3.) The DC output of the rectifier and filter circuit is fed into the analog input of the micro-controller. The built-in analog to digital converter of PIC 16F877 has been used for this purpose. The analog voltage levels are converted into digital numbers so as to be processed by the software inside the PIC.

4.) The software performs the necessary arithmetic operations taking the sensitivity of the accelerometer into account to achieve the true vibration levels. The peak vibration amplitude that could be measured with the proposed set-up is 9.807 m/sn2 (1g). The results of the acceleration measurements are displayed on 3 7 segment displays. By using the built-in USART of the micro-controller. The vibration levels are also monitored via a PC screen.

Schematics of the Project: project.bmp