Senior Project

Burnoutrevengekidd05

My name is John Turner and I am a Senior At Tri-County Voc. Tech. High School.· I am in Electronics and two weeks ago we worked on our senior projects in shop.· Now, in case your wondering what my Senior Project is I am taking an RC Car more specifically a deceptor RC Car and making it run own its own using a BS2 Microcontroller and a board of education.· The problem's, yes there are more than one ·unfortunately, is that I do not know··which of the three wires coming off of the rear motor are ground and which are for powering the motor.· I have a program for it I think but I'm not sure ·if it does anything because when I hook up the rear-wheel motor to the board the wheels run in reverse and that is irritating me a lot.
Please let me know if you can help me any and all suggestion would be very helpful and if you need any more information just let me know.
I'm so confused!!!·

Post Edited By Moderator (Jon Williams (Parallax)) : 11/28/2005 1:18:48 AM GMT

Whelzorn

well, remember that if it is a conventional DC motor, then there are only 2 wires that matter. You could just switch the 2 wires and the motor should turn the opposite way. But since it has 3 wires, it sounds like either a servo, or a motor with some kind of shaft encoder, or some other drive circuitry (like an h-bridge or something). Could you possibly post the code?

Burnoutrevengekidd05

Would post the code if I knew what that was but, unfortunately I don't know what the code is. No offense or anything but could you please restate the last thing you said about the code in English? If you could I could probably find out what the code is.

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John K. Turner Jr.

Steve Joblin

Let's take it one step at a time. A "typical" motor should only have two wires... so the first step is to understand what the third wire is for. We also need to understand how everything is hooked up. You have batteries, a Stamp BOE, motors, etc. You need to draw a picture of how you currently have everything connected. You also need to understand what the program in the Basic Stamp is doing, so you need to provide that as well. So let's review... we need to understand the hardware (how things are hooked up), and the software (the program code in the Stamp). Let's start with that.

Jim Richey

Your machine should have a mabuchi motor.It should have only 2 leads.Can you post a closeup?

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Thanks, Parallax!

SN96

It is also my understanding that you shoud not run a DC motor from the BOE or you will burn up the BS2. There needs to be a circuit with its own power supply that the satmp hooks to and controls the motor.

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Mike

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Burnoutrevengekidd05

I can do all of the above hopefully as soon as I get home today. More specifically the hardware and software and the pictures of everything and how it is all hooked up.

Thanks for your help guys! I really appreciate it and in the comming weeks I shall be relying on your information and the help you can give me to complete my Project.

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John K. Turner Jr.

Burnoutrevengekidd05

Duh.· I just remebered that my car is a transformer,· it changes form truck to buggy with just the push of a button on the remote.· Sorry about that.· Although that would explain what the third wire is for, and why the car kept going in reverse, it still doesn't explain why the program I have doesn't work.· Any suggestions?

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John K. Turner Jr.

John R.

John;

You haven't given us any more meaningful information, and we are not in much of a position to help any more than the suggestions and requests above. The fact that the car is a transformer does NOT (in our minds) explain a third wire from a motor.

Starting with the basics, there appear to be two issues we are dealing with:

1) How to connect the motor.

2) Your program isn't working.

I would suggest that before we tackle the program that isn't working, we need to determine how to run the motor, and if indeed you have a "motor", as opposed to a servo (which is technically a type of motor).

As far as number two, you stated you would be happy to post the code if you knew what that was. This also suggests that you probably need to do some homework, like at least looking through the "What is a microcontroller" book that can be found and downloaded from: www.parallax.com/dl/docs/books/edu/Wamv2_2.pdf As you stated that this is a "Senior Project", I would think some basic research on your part is appropriate. Until we know how the motor is supposed to be connected, you are only guessing that your program doesn't work.

Back on the motor, If it were me, I would check the resistance between the various motor leads with a multi-meter, and how/if that resistance changes while manually slowly turning the motor, and/or check the voltage and polarity with the voltage meter while the motor is running in the original device in both a forward and reverse direction. This may provide some clues as to what's going on. I would also make sure I could run the motor both directions by connecting a battery "by hand" or with alligator clips. In addition, the following information might help us help you on the motor connections:

• What color are the leads?
• What, if any, markings are on the motor, or molded in to the end cap(s)?
• What were they connected to in the original device?
• How many, and what size batteries were in the original device?
• Can you take and post a close up of the motor, showing any markings and/or the motor leads?
• Can you see where the leads connect to something "electrically conductive" (metal) on the motor?

Again, to emphasize, let's get the motor figured out first, then worry about the program. You also want to do this first so that you dont end up letting the smoke out of the STAMP. The STAMPS only have a very small amout of smoke to give...

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John R.

8 + 8 = 10

Post Edited (John R.) : 11/30/2005 3:45:29 AM GMT

Burnoutrevengekidd05

First off, I got my project running the way I want it to. Forwards instead of backwards (finally). But as to the motor itself until recently I have not figured out a way to get it out of the back wheel section of my car, but now I do know a way to get it out. I have to use this tool that I have that has a phillips head screwdriver on it but it can come out so that the tool and the screwdriver head form an "L" shape. The reason why is because after I removed the tires themselves form the car, there was still the problem of the wheels. They don't come off. Also there is the matter of a yelllow backing on the car which prevents me form accessing the motor itself. SO as to the matter of my motor, I have the two bigger wires connected to wires connected to P15 and P14 of the microcontroller that I am using. The wire connected to P15 is connected to ground, and the other one in P14 is connected to Vcc. The colors of the two bigger wires connected to the motor housed inside the rear wheels, are Brown and Gray. The battery is a 9 volt rechargeable pack (Nickel-cadmium I think, and give or take a little on the voltage). They were orginally connected to a circuit board currently housed inside the car. As for the code thing, a mistake on my part i didn't realize he ment the program. Will take pictures and post them when I get home. Also will add more info. when I get home.

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John K. Turner Jr.

John R.

John;

You probably don't want to be running the motor directly off the STAMP pins. Look for posts on motor controls and/or "H Bridge". Unless the motor has a VERY low current draw, you will exceed the rating of the STAMP and "let the smoke out".

Were you able to connect the two larger motor leads directly to a battery and have the motor run? If so, if you reversed the leads, did the motor reverse?

You need to break your problems down, and work them step by step.

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John R.

8 + 8 = 10