External Interfacing

[blabla]

Hi there,

I am doing my final year project right now, and I have a question on how to connect the digital binary input into the computer.

I am designing a car park monitoring system which counts the number of cars going in and out. The movements of car is sensed by a sensor and is transferred into a program written in Visual Basic to keep track of the number of cars.

My questions are:

1. How do I interace the sensor into the computer? Do i need to have an interface board installed? How can I utilize the serial or pararrel port available?

2. Can Visual Basic do the job well??


Please help...

Thanks....

 

[Demon-Xanth]

Generally a DIO card is the best, however there is ways to interface these to other various ports. One cheap and easy way could be to interface via a Gravis Gamepad via the joystick port. You could simply utilize the existing drivers and sense one of the buttons being pressed by having the digital inputs switch relays to close the switches on the pad (simulate button presses).

Advantages: cheap, easy
Disadvantages: slow (probably not an issue), only 4-6 usable lines

 

[CTho9305]

you could also interface to the serial/parallel ports, but I think its a pain to do and I dont remember how

 

[nam ng]

For quick, dirty but reliable solutions, it's best to utilize what's readily available, and preferably the bulk of work supplied well proven by time.

Example... Use a thrown away/surplus 3 buttons mouse, the midle mouse button hardly used by anything, allowing full function mouse with a single input, cheap brand new could be less than $5, the button-switches on the mouse came with built-in debounce CKT, built-in OS mouse driver can optimize filtering functions, add a little bit of your own customize effort make short work of the whole thing.

 

[Killbat]

It's all about the parallel port, the world's best port ever! I've done some parallel port tinkering (with VB, to boot), so if you'd like to know some more about that area, just throw an Email my way: killbat@swbell.net

 

[Blundar]

I vote for the parallel port too, if a quick + dirty hack like a joystick or mouse will not work for you.
You can use an optoisolator or just a couple of transistors to interface your switch with a circuit that takes a parallel line from ground to +5v and monitor this. Most of what I ahve done is the reverse - pushing parallel lines low/high hooked to optoisolators to switch things on/off based on parallel port. It was a long time ago, and done in dos C not VB 🙂
good luck!