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DarthMessiah15

Very Basic Questions

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Looking for someone to offer some basic answers.

 

I'm a sophomore CoE/CS double major so the coding shouldn't be an issue, I just have a question to how i should fundamentally set up the project i'm going for. basically, I need to make a prototype that will give some type of warning, say an led flashing for a controlled amount of time, then i need it to do some mechanical task, then the inverse of said task. for example, turn a DC motor. my first question, is about the output voltage/current of the board.

 

1) is it relational to VCC or does it differ by chip and how do I find this information?

 

2) I guess this is dependent on question one, but for most things like this, would the chip more likely just control some sort of relay or some other device to power whatever i'm wanting to do externally? or is it dependent on how much juice i need to run whatever it is. I'm just kinda curious what's more common practice so that I can design from the ground up correctly.

 

3)this question is a bit more involved but how difficult would it be to make a GUI for this simple program, and be able to change the variables such as time before each "run." I kinda figure this would involve some external program that generates the C code and compiles it to the chip but as I said, extremely novice at this point. any help would be extremely appreciated.

 

thanks

CM

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Hey CM, I'll try to answer your questions as best I can. So far I've only used MSP430G series, but I think the answers should be relevant to other MSP430's.

 

1.The output volatage from the port is Vcc at high and ground at low. That seems to be true of most digital chips I've worked with.

 

2. You can check the datasheets for max current from the ports. Generally, a couple LED's are fine to be driven directly by the chip, but I think you'll need a transistor to switch a relay or motor. I believe the individual pins have a relatively low current limit as well as the port as a whole. I usually just find out how much current I want to draw and check the datasheet to see if it's too much.

 

3. As far as a gui, I assume you mean a gui on your pc? I haven't done much with MSP430 to pc communication, but I think an ftdi usb-serial chip would work. I've used it before with avr, and there's a lib called rxtx for java that worked smoothly. Something like that would get your pc communicating with your microcontroller. 3.3V FTDI breakouts are $15 on sparkfun. I think some others in the forum have more experience with this. There are cheaper solutions as well, such as altering a cell phone cable.

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for the gui C# can be fairly easy to do and it even has a serial port object you can use. My blog hs an article about serial communication

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ok thanks. the GUI isn't really necessary, but basically i just wanted to be able to control some time constant editing directly before running the code. so I was thinking about writing a program of some sort that will then generate the code, compile it on the MC, then start rolling. anyone done this?

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Could you have several preset time constants coded and use a switch to toggle between them at the beginning of, or during runtime? You could also turn a knob connected to a potentiometer and change the timing during runtime with that. I don't mean to sidestep your question, but the method you're suggesting just seems overly complicated and unusual, and I don't see it being the best solution except in some rare and very specific cases.

 

You may very well be dealing with one such case, but I feel like I should mention some more common and possibly more practical solutions.

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it's more of just making this for someone that would be much more comfortable using a GUI for the adjustments. I'm kinda being rushed to make a prototype for a buddy who's doing some medical research. and he just think's there's an entire higher level of legitimacy by launching it from a desktop. does that make sense? more of just trying to fulfill a request more than it's an actual requirement.

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How about Java then? Java has communications API (unfortunately, it's not available on all platforms out of the box, there goes your portability claim Sun/Oracle.)

It's fairly easy, you can do very nice standalone GUI app using Swing, or you can use Java Web Start technology.

Anybody with spare time this coming weekend?

 

Few years ago, I was playing around on my Mac with products from Serialio, but not sure how current their development is now.

 

When searching for serial Java solutions, I found some interesting stuff. Maybe we could create a similar universal front end app for easy interfacing with LaunchPad?

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