Fall 2009: Projects created by Students as part of course EP-315 on Microprocessors

Junior Year Engineering Physics

Department of Physics, IIT Bombay

Course Outline

Course Instructor: Professor Pradeep Sarin

Teaching Team: Nitin Pawar, Swapnali Gharat, Electronics Lab Physics Department. Rohit Garg (TA)

Project Kickoff Instructions

Project Close-out

Click on the project names to download/view the video. Videos are in MPG format (about 25 MB each)

Projects (Click on project names to view video presentation) Reports(PDF)
Cosmic Ray Detector - TDC

Team:Abhirup Nath, Aditya Pathak, Amol Patwardhan, Tejal Bhamre

Abstract: This project started out as an attempt to build a cosmic ray detector out of common fluoroscent tubelights. The Argon filled, phosphorous coated tubes act as ionizing radiation detectors. Coincidence between a number of tubes arranged one below the other as a cosmic ray particle traverses them allows tracking. The end result was a multi-hit Time-to-Digital signal converter (TDC) implemented using the programmable micro-controller. This allows for a lot of in situ flexibility in the TDC logic, since the micro-controller can be reprogrammed on the fly over USB.

Report
Spectrum Analyzer

Team:Harish Ramadas, Yogesh Patil

Abstract: The Atmega168 micro-controller's 10-bit ADC is fed with an analog signal. It can be any 50-ohm impedance analog signal in the 0-5V range, we chose an audio signal captured with a cheap electret microphone amplified and bandpass filtered between 200-1500 Hz. The micro-controller does a real-time discrete Fourier transform and displays the results as a bar chart in frequency bins on an LCD display.

Report
Bar-code scanner

Team:Arjun Hegde, Safeer C, Nikhil Jain

Abstract: A scanning device for bar-codes printed on cards. We use a fixed laser (from a laser pointer). The card with a bar-code printed on it is placed in a carrier. The carrier is driven by a stepper motor across the field of the laser beam and the reflected beam is captured on to a photo-diode. Signal from the photo-diode and the speed of carrier movement is fed to the micro-controller and used to decode the bar-code. We wrote a user interface for the entire project in Matlab.

Report
Precision servo controller for SHG crystals

Team:Sakshi Jain, Sumantra Sarkar

Abstract: A precision controller for a second harmonic generator (SHG) crystal is to be designed. The output of an SHG crystal depends on the phase matching angle of the incoming waves. For perfectly matched phases, the output is maximum. Normally one adjusts phase matching by introducing small delays in either path length. We did a proof-of-principle demonstration using two peak detectors to simulate the SHG crystals. A potentiometer controlled by an error-correcting algorithm running in the micro-controller servos around the maximum output point. Flexibility of programming allows us to substitute a PID algorithm for the servo control.

Report
Solar Tracker

Team: Salil Tambe, Mayank Chaturvedi, Mohit Pimpalkar

Abstract: A device to track the direction of the Sun. Typical application would be to control direction of a farm of solar light collection panels. It is built with two axis-degrees of freedom - horizontal (theta) and vertical (phi). The principle is to have two photo-diodes separated by a piece of opaque board mounted on a platform controlled by stepper motors. The micro-controller measures the difference of signal between each photo-diode pair and simply moves the entire platform over to a position in that axis until the difference becomes zero. By servo-ing around this 'zero-difference-in-photo-diode-pair-signal' point the device follows a light source in both axes as shown in the video.

Report
Touchpad

Team:Pranjal Bordia, Saket Patkar, Rishi Swami

Abstract: A touch-sensitive panel made with recycled ESD protective sheets (the stuff we normally lay out on electronics lab tables to protect ESD sensitive devices while working). These sheets have very high point-to-point resistance. So we apply a potential drop across it, and some raster scanning at high frequency to get high resolution from a 10 inch square sheet. The user interface was written in Flash.

Report
Air Guitar

Team:Nancy Aggarwal, Swarna Ramenini, Radhika Gupta

Abstract: A matrix of photo-diodes is illuminated by a light source. By waving your hands in the middle, light to some of the diodes is blocked. Signals from the diodes are multiplexed and fed into the Arduino micro-controller. We can use them as digital ON/OFF signals to trigger 'distortion' algorithms running in the micro-controller, which then does the real-time processing and puts out stereo analog signals (0-2V to be amplified further) to speakers. Due to problems with PCB fabrication our final project demonstration had to be done with a reduced number of photo-diodes.

Report
Game Controller

Team:Y Praveen Kumar, Abhishek Chandram, Vaideesh Loganathan

Abstract: A simple 'shoot-to-kill' game was written with a Matlab GUI, and a controller for it was built using the Arduino micro-controller and an accelerometer.

Report
Braille eBook Reader (work in progress)

Team:Mishel George, C.P. Varun, Soham Basu

Abstract: A handheld self-contained device that connects to a PC over USB. It downloads eBooks from the PC and displays them in Braille characters. The characters are formed using little pixels controlled by pins of shape memory alloy - they can be printed and erased repeatedly. A lot of work went into ergonomic design oriented towards blind people: a jog dial scavenged from a mouse to scroll lines of Braille text and specially designed cylindrical magnetic USB connector which can be attached to the device without bothering about its orientation.

Report

Hardware

All the above projects are implemented using the open-source Arduino microcontroller platform. The core is the Atmega168 16 MHz 8-bit microcontroller made by Atmel. It has 16 digital I/O lines and 6 I/O lines which makes it very easy to interface it to hardware (and a particular favorite among robotics hobbyists!)