Speedometer Question

[ngeronikolos]

Hello my friends,

I am going to make a speedometer project using a pic16F628 microcontroller (for my rc model car) display the speed of my car on a display!!!
I do not have enough knowledge about how can I measure the speed of my car.I read in the forum that you can do that using a hall effect sensor.What sensor is that?Please I need everything useful(links-projects-schematics ext)

Also,how can I drive a Calculator’s LCD.

Thanks in advance
Nikos

[Bill H]

Hi there Nikos,

A Hall Effect sensor is used to either count or measure the duration of a magnet going by.
It is typically mounted near a drive shaft or wheel. A small magnet is attached to the moving part.
There are two basic methods of caclulating the speed of the magnet going by. One is to count the number of times it goes by in a given time frame. Or, measure the amount of time it takes to go by in a single revolution.
Both methods have tradeoffs. Research the COUNT and the PULSIN commands.
Interfacing the calculator display is way too wide open. There are so many variables it's hard to address.
Good luck as you climb the PBP learning curve.
Bill H

[ngeronikolos]

Thanks Bill,

Do you have any expirence with any kind of hall efect sensor?

Can you suggest me any chip?


Thanks

[ngeronikolos]

Do you thing that this Sensitive Two-Wire Chopper-Stabilized Unipolar Hall-Effect Switches A1140-43 is OK for my application?
see datasheet:
http://www.allegromicro.com/sf/1140/

[Bill H]

It looks like the Allegro Hall device should work fine.

Bill H