UNIVERSAL REMOTE CONTROL

Kevin Chipalowsky & Jennifer Librach

Introduction

A universal remote is a common everyday household appliance. Used to do everything from TV/Video/Cable to ceiling fan control, this project is a extremely versatile product.

We planned to have a 32-button remote that could replicate the IR characteristics of a VCR & TV remote control.

For our final project, we undertook to create a replica of this product. Using the Atmel 8535 microcontroller chip, we believe that we can accurately replicate the characteristics of the device.

We also wanted to see how hard it would be to use the microcontroller without the limitation of a prefabed ATMEL board. We used the board to test and program our device, but the final project is a fully portable project. Basically, we thought it would be cool to be able to bring our project home with us to control our own TV.
Results

Our final product did not work up to our proposed specifications. It did record pulses from OEM remotes, and it did play them back. The VCR that we are testing our device with receives the IR pulses and behaves appropriately. Unfortunately, our inexact replication sometimes makes the button appear to be pressed multiple times (it will turn on then off immediately). Perhaps, it did not recreate them precisely enough to be interpreted by OEM receivers correctly. Looking at an oscilloscope, our recreated waveforms are nearly identical to the OEM generated ones.

One of our problems was too weak an infrared transmitter. The project must be close to the VCR and aimed directly at it to work.

Also, our IR messages were played back with more noise than appeared in the original signals.

We discovered that the 8535 did not have enough memory to record complex signals for 30 seperate buttons as we had originally planned. All IR signals turned out to be far more complex than we had guessed. Realistically, it had enough memory for about 5 different buttons.

Improvements

Better Box- We believe that we could have made an extremely compact and light-weight design project. The actual chip and circuitry takes up very little space. With accurate soldering and ideal parts we could have made the project 1/8 the current size.
Stronger LED- The remote controls we have been using to program our device were detectable by our IR receiver 5 ft away from 90 degree angles, the LED had to be within 10" of the receiver and directly in front of it.
Research- We should have done more research on the tolerance of cable boxes. We don't know how exact the replication of the signal has to be. We also assumed that we could generalize from only 2 remotes that behaved similarly. It turned out that a 3rd cable box remote has different characteristics if you hold down a button then the other two remotes have.

Link: http://instruct1.cit.cornell.edu/courses/e...ts/s1999/kevin/