Introduction: RC CAR (Parallel Port Interfacing)

INTRODUCTION (WARNING CODE CAN ONLY RUN WITH WINDOWS XP)
This project was about operating a remote control car by using an input device connected with a computer, for this purpose we had to connect the remote of RC Car with the computer so that when we operate the computer, remote would start its function and car will be operated. Therefore at the same time we had two grounds to play one was software development and second was hardware interfacing.

Step 1: Materials

S.no.    Name                                                               Quantity                                                    Cost (In Pakistani Rupees)

1-) DB-25 cable (parallel port cable)............. x 1.....................................................................Rs 250
2-) Gender changer (optional).........................x 1......................................................................Rs 100
3-) Bread Board..................................................x 1......................................................................Rs 140
4-) Wires..............................................................2 meter.............................................................Rs 25
5-) Transistor (Mps a06)...................................x 4.(or any general purpose transistor).....Rs 8 x 4
6-) LED's ............................................................,x 4 (two red two green)..................................Rs 4 x 4
7-) materials for soldering..........................................................................................................
8-) RC Car............................................................x1.......................................................................Rs 350 -900
9-)db25 male header/female ..........................x1.(depending upon your cable)..................RS 100

Step 2: Getting Started (Hardware Phase)

Hardware phase
                              first of all open the remote of the Rc car. You will analyze that there are four switches. when we press the button each switch is closed.. Before pressing the button turn on the remote and check the voltage across the terminals of the switch  it should give a value.. after pressing the switch hold the button and check the voltage it should show zero..

this concludes that our remote is working on short circuit technique. that is if there is a voltage across the switch and when its pressed it is short circuited.

Observe that one wire is common in all the switches its the ground of the circuit. which concludes that we need to solder five wires in the remote. one for each switch and one for ground.

it can be checked that when u short the ground wire with any of the switch wire the car performs the action of the switch who's wire is shorted if all the four functions are performed then it means u have picked the right ground. and the right switch wires.

here are the pcb design and the simulation of the circuit for interfacing (download parallel port circutary)

Step 3:

TRANSISTOR (as switch)
                                              Now when we press the button manually the two terminals of the switch join together.
but from parallel port we can only have voltage signal to activate the switch. we use the circuit transistor as a switch for it.

Working
               when the voltage at the base of the transistor is one (5V) then the emitter and the collector terminals are short.. as if we short them manually.hence our functionality is achieved.

these transistors were mounted on the breadboard one can also make a PCB or vero board

Leds are just used for protection as we ar shorting the terminals of the parallel port (approximately) because ther is a 0.7v drop accross the transistor so just to dissipate power and also for little beauty : )

Step 4: SOFTWARE PHASE

I Wrote a program on C++ works fine.
just control the car with arrow keys

Download the .zip file for the complete code (the code only runs on windows Xp and not on windows 7 as mentioned before).
i have tried it on windows 7 (64-bit Ultimate 6.1 build 7600) but did not worked fine.

here is a demonstration video link
http://www.youtube.com/watch?v=pr4aLUDTiiQ&feature=youtu.be





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dinitrogenoxide@ymail.com

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bread board testing (LOW QUALITY)