Wednesday, October 22, 2014

Optically controlled servo motor

This is demonstration project to control servo motor movement using physical marker and normal video camera. In this project video camera capture the movements of marker and calculate rotation angle based on that. This calculated rotation angle is feed to the servo through small MCU based interfacing unit.

In this project video processing and tracking is performed using ARToolkit and controlling of servo is carried out using PIC16F628A microcontroller. RS232 interface is use to communicate between PC and microcontroller.

Interfaces in optical servo controlling system

This application detects movement of marker on Z axis (yaw) and transforms it into another numerical scale to manipulate the servo motor. Processing application is written using Visual C++ and configured to work on Windows operating system(s). The marker used for this application is needed to be a "square with some symbol" and user can train this system for any compatible marker. As per our tests, standard 3MP or higher grade web cam is sufficient for this system.

prototype assembly of servo driver and servo unit

To demonstrate the exact behavior video is much more suitable but my web cam is used for this project and I don’t have spare web cam to capture the operation of this project. As per our observations servo movement is highly sensitive to the changes of marker object and the movement of the servo motor is also linear and smooth. The propagation time is little bit slow due to serial interface and this can be improved by using high speed I/O interface like USB port.

The source code, servo driver schematic and firmware of this project are available to download at under the terms of the GNU General Public License version 3.0.

Saturday, October 11, 2014

Digitally controlled 2.1 channel analog audio power amplifier

This article introduces high quality digitally controlled 2.1 channel analog audio power amplifier system. This project is mainly based on TDA7377 AF power amplifier and PIC18F452 8bit microcontroller. Basic features of this receiver are 2 × 6W + 20W audio output power, ±14dB bass and treble controls, fully configurable +35dB bass booster for sub-woofer and satellite speakers and loudness switch.

This system use commonly available electronic components and all the integrated circuits are in DIL packages. This amplifier consists with few UI elements such as 2 push buttons and 1 rotary encoder. All the menu navigation can perform through rotary encoder.

Prototype version of 2.1 channel audio power amplifier project

Entire amplifier can build on 147mm × 80mm PCB and all the PCB design files are available to download at project homepage.

This is an open hardware project and all the firmware source codes, design files are covered with Mozilla Public License version 2.0. All the above content and complete documentation is available to download at