Help: How to control DC Motor using VB Expres 2005

Hello,

Im new to VB 2005 and I would like to know how to make the dc motor accelerate when I press the "a" key and decelerate when I press the "d" key and spacebar to make it to stop. Lets say for example I have 3 speed mode(1,2, and 3), if I press the "a" key twice it will go to number 3 speed and if I press the "d" key one, it will go to number 2 speed, pressing "d" again will go back to 1 speed and finally, pressing spacebar will stop the motor. Im using SCR as controller and pin 2-9 of the parallel port to interface with pc.

Thanks in advance!

Moved to VB.NET

Sounds like a school project. You should have built the circuit already to drive the motor. So it will be just writting keypress code to increment or decrement some output to the parallel port.

Well I personally would use the serial port just because it is easier to use and what you want to do doesn't require high data transmission speeds. But anyway...

You need to figure out what commands to send to the controller chip. The VB part of this will be easy because once you define the commands you will just design up some simple controls. I would make an on-screen simulator first. Once that works correctly then you could just add the output.

Hi, I have another question. How can I create a counter using LDR as an input? I want my program to count the rpm(rev/min) of the dc motor. Is it possible to use a timer? could you give me any reference code. Thanks.

Btw, im using parallel port.

I dont think anyone is going to do your project assignment for you but if you post what code you have written Im sure we will be able to help guide you along your way.

i am using this code below to control the speed of the dc motor when the key is being pressed.

Code:

---

    Public Class Form1

    Private Sub Form1_KeyPress( ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles Me .KeyPress

    Select Case e.KeyChar

    Case "a"

    If CInt(labelspeed.Text) < 3 Then

    labelspeed.Text = CInt(labelspeed.Text) + 1

    End If

    Case "d"

    If CInt(labelspeed.Text) > 0 Then

    labelspeed.Text = CInt(labelspeed.Text) - 1

    End If

    End Select

    End Sub

    End Class

---

now my problem is that, i don't know how my program will count the rpm of the dc motor using ldr. my classmate said that i should use a timer and use the inp(889) to receive a signal from ldr to my program. but i dont know how to generate a code using that timer. hope you can help me out on my project. thanks.

What is an LDR?

Depending on your DC motor, it may be impossible to get a rpm count, maybe some inaccurate numbers at best.

light dependent resistor (LDR) as a sensor.
can u give me a reference code even if it is counting inaccurately? thanks

No, as Im not the one in school. It wouldnt be fair to the other students. Plus, it may be dependant upon the motor and circuitry being used.

im using ldr to sense the revolution of the motor per minute or per second, pls help im a beginner and still don't know how to program well.

my program is not working


dim x as integer
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
Label1.Text = Inp(889)
X = X + 1

End Sub

End Sub

to be more easier for us both, and not to be unfair for others like what you have said a while ago, lets make the code easier. lets say i have a button tool.
by clicking the button how will i compute and display the no of times i clicked it per minute?

There are a couple of ways you could work out RPM:

1. Count pulses and test the count after a set period of time, eg. 1 second.
2. Detect how much time passes between pulses.

I would suggest that option number 1 will be easier.

Take your input and increment a counter with each pulse you get.

On each timer tick, read the counter value and multiply it by 60. This will give you RPM assuming a tick frequency of 1 second, and also assuming you have one pulse per revolution of your motor. After you have calculated a result for that tick, reset your counter variable.

Really though, that's mostly just basic maths.

How you read in the input from the sensor, I have no idea, but I assume you already know that, or it forms part of the study material for you project.

As has been mentioned, I don't think anyone will write out a whole load of code for you, but that should give you a nudge in the right direction.

tanx Andy_P i'll try to work on it.

Public X As Integer
Public y As Integer

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick

Timer1.Interval = 1000

X = (X + 1)

Label1.Text = X ' this show the timer tick every sec

label2.text=inp(889) 'signal coming from my ldr




you have said that the count of my signal should be multiplied by 60, then should i declare an integer to show the rpm??