SparkFun Forums

[DLDude]

Hello, I'm a student at Ohio State and I'm trying to put a Witilt onto a model rollercoaster to get the G values over time. So far I've been able to connect to the Witilt via Hyperterminal on a Mac, and then used that data to graph it in Excel. This looks OK, however we use mostly PC's and we need to be able to graph it in real-time. We do have access to Labview, however, we would like to be able to put this on our laptops so that we can use it to tutor highschool kids. Any suggestions on how to get the Witilt data to graph over time, in real time? Any cheapish software available?

[Antiporcupine]

MATLAB is your friend.
<_<
No really, in MATLAB, you can simply read a packet of data, enter it into the array, and refresh the figure, all dynamically. I'm a UMaine student myself; I've seen it done in other projects here, and will soon be doing it myself for a project. Student ed. costs $80-something last I was aware. You'll probably also find plenty of uses for it later in your studies; since I bought it, I've used it for probably 2/3 of my ECE classes.

Minus

EDIT: Just realized you said laptops plural. The student MATLAB license is only good for two PCs; I don't know how many you plan to use. This could be potentially problematic.

[DLDude]

We do use Matla at OSU and I do have it on my laptop. What should I read up on as far as importing the data through Bluetooth in real-time and graphing it? I've gotten data on Hyperterminal, which I've used to graph in Excel (and I'm sure could do the same in Matlab), however I'm looking for a more real-time way of doing it. Matlab would be nice because I could code in some smoothing algorithm to cut some of the noise out (it's very noisy at the moment).

I've also tried to read up on Simulink to connect to bluetooth but havent come to any conclusions.

I've also got Visual Basic, is there a way to write a very simple program in that? I mean, ALL I need is a G vs. Time graph to go for under 1 minute. Nothing special at all.

[Andrew02E]

My two cents on Visual Basic and reading serial data: unless you have some reliable third-party serial interface, MSComm is ugly.
If you're not worried about the serial interface, then there's a few very simple drawing commands in VB (ie. Line(x1,y1)-(x2,y2)) that, after a short learning curve (no pun intented), can be easily used to draw a plain graph.

[DLDude]

I'm starting to look into reading the data via serial COM ports (I'm very new to this type of stuff). I want to try to do it in Matlab first because I am more familiar with that program. What I dont really understand is how I can call out the Witilt. You have to press '1' so it starts sending G data, however it looks like Matlab is going to want to just take in strings of numbers.