PyroElectro.com

ThePyroElectro · Posted: Mon Nov 12, 2007 10:36 pm Post subject: DC Motor Control

Kevin · Newbie Pyro Joined: 23 Nov 2007 Posts: 17

Hi Chris,

Firstly, I want to say that you have an awesome website for electronics tutorials. Keep up good work. Smile

I have a question about the DC motor's speed. I have read the datasheet of the LMD18245, and I understand that to change the speed, you simply change V DAC of {M4,M3,M2,M1}. Therefore, you have the following code for full speed:

PORTC = 0b00001111; // 0x0F Full Speed

For 3/4 full speed, shouldn't it be 15*3/4 ~ 11 = 0b00001011 or am I missing something here?

This is what you have for 3/4 full speed:

PORTC = 0b00001110; //0X0B 3/4 Full Speed

ThePyroElectro · Posted: Fri Nov 23, 2007 11:02 pm Post subject:

Hi, thanks for checking out the site.

You're right.

11 = 0x0B = 0b00001011

Looks like i made a typo. I'll go ahead and correct it in the tutorial.
Thanks for the comment

~Chris

Kevin · Newbie Pyro Joined: 23 Nov 2007 Posts: 17

Dang it, they charge a shipping fee for the H-Bridge driver sample now. Do you know a "free" alternative IC? Very Happy

ThePyroElectro · Posted: Sat Nov 24, 2007 3:50 am Post subject:

BushidoShonin · Newbie Pyro Joined: 05 Mar 2008 Posts: 4

When programming the PIC can you use variables to represent a specific port/pin? somethin like this:

Break = "PORTBbits.RD0"; // Brake
Dir= "PORTBbits.RD1"; // Direction

then later when you want to do something with these all you have to do is:

Break = 1;
Dir = 1;

Would something like this work?

ThePyroElectro · Posted: Mon Mar 10, 2008 4:05 pm Post subject:

Sure you can Cool

, use the #define statement at the very top of your program.

Example (top two lines are what you're looking for):

BushidoShonin · Newbie Pyro Joined: 05 Mar 2008 Posts: 4

Thanks a lot, but I have a ton more questions.

First: How would you define a number variable? Like this?
int var1 = 123

Second: How would you state a random number? Like this?
int randNum = (rand() / RAND_MAX) * 100 //Random number between 0 and 100

Third: When defining a var like in my last post, does this all have to be outsite the main function?

ThePyroElectro · Posted: Mon Mar 10, 2008 10:34 pm Post subject:

Hi BushidoShonin,

From your last few questions, I'm led to believe you don't have much experience programming in C/C++ Surprised

. If that's the case I'd really suggest finding a free online "Learn C in 24 Hours" ebook. You can find one just through a simple google search and then skim through it to get the basics.

Exclamation

If that's not the case, here's the answer to your questions:

(1)
In C numbers are stored in numerical data types (int, long int, double, float to name a few). The proper syntax for declaring a numerical data type is:

1976922 · Newbie Pyro Joined: 26 Nov 2009 Posts: 1

Hi Chris,

According to your project, it just utilize h-circuit and processor to control the motor. Do you have an experiment that using h-circuit and motor encoder/decoder via processor to be a close loop circuit to control the motor?

Since I have some confuse for the motor encoder, would you please to give me some comment or suggest?

Since I know that has chips to be the encoder/decoder, the motor which I have included a internal encoder. Is this encoder's function can be the Optical Encoder. Moreover, I don't have decoder chip. How about the flow path for program of decoder in 8051.

Thank you so much.
Matt

ThePyroElectro · Posted: Tue Dec 29, 2009 7:59 am Post subject:

Hi Matt,

I'm working on a write-up like that. I don't currently have any tutorials or projects with closed loop systems. Sorry!

Best of luck.