# Need Help w/ School Project....

#### uuuu2c

Joined Sep 21, 2006
5
Hi.....

I'm new to this board and relatively new to electronics and programming. I decided to take a year long project oriented course and had this project dropped on my lap. (I have basic knowledge of electronics and C programming.....hopefully it'll help.)

I have to basically take 4 inputs (square waves) of various frequencies and display a coinciding "meter"-like representation on a 7" TFT dispaly. I am assuming that I will require microcontrollers since this project is to be self-contained. The only thing that I can have is a +12V powersupply. Our instructor compared our project to a dashboard of a car where the speedometer and tachometer would use similar inputs and display on the guages. If I am able to finish this quickly, I am to add any customization as I require.

ANY help would be extremely appreciated as I have tried to do some research online and have come up with a blank......

#### beenthere

Joined Apr 20, 2004
15,819
Hi,

Not enough to go on. How are the data to be displayed? Simulated dial gauges? What are the significant variables in the four pulse trains? Have you made the selection of hardware for the project? Have you any ideas about hoe to take in the pulse trains and deal with the variability?

#### uuuu2c

Joined Sep 21, 2006
5
Well, that's the problem. Since this is a project that is supposed to take the entire year, we are supposed to do the investigations ourselves and plan out the project ourselves.

The gauges on a car was just used as an example. We are actually responsible for coming up with any generated frequencies that we wanted. After doing some research, I came across the following:

Square wave
0 - 5V
~4000 Hz/1mph

As well, I was thinking of using the following other wave generators.

Temperature (not sure of which sensor yet)
Logic (on/off)
Sinusoidal wave

Since I can generate the wave any way that I want, however with appropriate sensors, it ultimately does not matter what types of waves and where it comes from.

As for the displaying, I was thinking of using C. However, I am not sure how I would implement a TFT screen to show images using C.

I guess that I am quite lost still since I have so little background in each of the components that I must deal with. I will read over suggestions and also post updates of what I come across. PLEASE.....any help is extremely appreciated.

#### beenthere

Joined Apr 20, 2004
15,819
Hi,

A couple of observations: 4000 Hz/mph is a bit over the top. You only need a frequency that will allow you to make the measurement with what is sufficient accuracy. If .1 mph is the resoultion, then 10 Hz/mph is enough.

On/off isn't a frequency - it's just a state.

Temperature is normally measured by a change in voltage coming from a change in resistance. You could make this a frequency with a voltage-to-frequency converter, but it's lots easier to just deal with the voltage change.

What's the on/off and sine wave supposed to represent?

You use C to write the program that will take in the frequencies, do the conversion into engineering units, and ultimately drive the display. You will need a microprocessor and support ic's to do this.

You'll need to learn enough to be able to know why it's necessary or not to have different waveforms to represent your measured variables, what it will take to convert then into engineering units, and how to control a display using whatever microprocessor you are using. Gonna be a busy year.

#### beenthere

Joined Apr 20, 2004
15,819
Hi,

A couple of observations: 4000 Hz/mph is a bit over the top. You only need a frequency that will allow you to make the measurement with what is sufficient accuracy. If .1 mph is the resoultion, then 10 Hz/mph is enough.

On/off isn't a frequency - it's just a state.

Temperature is normally measured by a change in voltage coming from a change in resistance. You could make this a frequency with a voltage-to-frequency converter, but it's lots easier to just deal with the voltage change.

What's the on/off and sine wave supposed to represent?

You use C to write the program that will take in the frequencies, do the conversion into engineering units, and ultimately drive the display. You will need a microprocessor and support ic's to do this.

You'll need to learn enough to be able to know why it's necessary or not to have different waveforms to represent your measured variables, what it will take to convert then into engineering units, and how to control a display using whatever microprocessor you are using. Gonna be a busy year.

#### uuuu2c

Joined Sep 21, 2006
5
Thanks for some suggestions and insight into this project.

As for the temperature, I guess that I can just leave it as a voltage.

The ON/OFF is just a logic on/off. So, when the input is ON, there will be a 5V constant signal. When the input is OFF, there will be 0V.

The sine wave would be a non-square wave but more of a A/C type of wave. Since I'm supposed to use different types of input to translate into a display representation, I thought that this would another input that I could use.

In terms of a microprocessor and support IC's, do you have any suggestions? I don't know what would be too powerful (in terms of computing power) and what wouldn't be.

#### beenthere

Joined Apr 20, 2004
15,819
Hi,

I'm a little puzzled by your last post. It makes it sound as if you have been given the assignment, and then dropped into free fall.

While I might expect the instructor to direct you to figure out how to assemble the hardware and write the code, I find it har to imagine that the school would provide no resource for you to use. That is, the hardware to choose from.

In order to use a microprocessor, it is necessary to have a means of programming it. This typically costs in the hundreds of dollars for the programmer and support software. That's a lot to have to eat when it's utility to you in the future is questionable.

There are simply too many microprocessors on the market to try to suggest "the" correct choice for your project. I would expect the institution to have at leat one line of microprocessors on hand, along with the programmers for same. Otherwise, there are just too many choices to have to make.

Surely there must be a lab with the hardware you need....

#### uuuu2c

Joined Sep 21, 2006
5