LED Tachometer - PIC

[burg]

Hey,

I'm looking to do an LED Tachometer for a student run race car competition. I would like to use PIC's to run the LEDs. What I want to know is if it is possible cause I only have a short period of time to learn PICs and get it working.

The signal coming in would be a frequency that would vary with the RPMs of the engine. As the engine RPMs increase, so does the frequency, and in turn more LEDs are turned on (8 LEDs in a row, increase with RPM). I will have a frequency to voltage converter (0-5V) which will then go into the PIC. The PIC will use a pre-determined formula to compute the RPM from the voltage (i.e. 2.3V is 4000RPM). The voltage would also relate to a Look Up Table (anyother way on a PIC?) that would determine the voltage range for each LED. So if its in a certain voltage range, that would determine the LEDs that should be on.

On top of that, I have a signal coming in that is from the ECU that will determine the best shift point. When the shift point is reached (the RPM number) I want the PIC to flash all the LEDs.

So is this all possible using a PIC, and what should I focus on?

Thanks

 

[SYE]

Hi,
If you already have the frequency to voltage converter setup there is no real need to use a PIC, you could use a simple LED bargraph driver. However if you really want to use a PIC there is no real need for the frequency to voltage converter, any PIC with a CCP module can easily do the job, something cheap like 16F628 will do.

 

[fever]

i hope below links will help u

translated **broken link removed**

http://www.walktronics.de/html/led-drehzahlmesser.html

 

[bananasiong]

Wow!! That's good project. But i can't understand the language

 

[burg]

The second link is more to what I'm looking for, but my lord, 32 LEDs? Wow

bananasiong - just type the link of the website into this site, and ask it to translate from German to English and it'll be mostly translated... http://babelfish.altavista.com/

Thanks for the suggestions, any others?

 

[fever]

well if u fnd any more simple and easy let me know.i too need it.

 

[Arup]

have any one built the above project? is it working?

Arup

 

[burg]

I've modified a PIC circuit diagram to include an IC 2917. It converts a Frequency signal to a voltage. It's quite a nice IC, and the Datasheet for it explains it all.

The signal comes into the IC, gets converted into a voltage between 0.7 - 4.6 I believe, then will go into the PIC where it will then be determined which voltage level it is at and output from the PIC to turn on the corresponding LED.

I havent actually programmed or tested the circuit, I've been waiting on a programming board and PCB's to be made for it.

 

[Sceadwian]

The PIC will be able to more accuratly determine the RPM if it determines it itself instead of being converted to a voltage and then read as an analog signal. Reading the number of pulses can be as simple as setting up a timer to run on an external clock signal (The tach signal) and then timeing how long it takes for that timer to overflow.

 

[Arup]

anybody have a working circuit?

 

[student1616]

well i know another one.but it uses digit display instead of led's.
http://www.josepino.com/pic_projects/index?tachometer2.jpc

its simple to built.if some one interested in it pls can u design a layout.i desperately need it.(prob. in eagle cad)

 

[burg]

The PIC will be able to more accuratly determine the RPM if it determines it itself instead of being converted to a voltage and then read as an analog signal. Reading the number of pulses can be as simple as setting up a timer to run on an external clock signal (The tach signal) and then timeing how long it takes for that timer to overflow.

Problem is I have other signals coming in, and didn't want to mess around with the clock. The accuracy of the Tach isnt required because it is only an LED indication. It can be off by +/-10% without much difference, probably even higher.