Memsic question

Electronegativity

I am looking at a Memsic accelerometer that I bought from Parallax with a jeweler's loupe.
There are two small unlabeled components on the board.
The manufacturer reccomends 2 capacitors and a resistor to limit the noise.

Are there components already on the little board?

Also, there are only 6 pins coming out of the little board upon which the accelerometer is mounted, but the actual component has 8 pinouts.

What's up with that?

The documentation that came with the device, and what I could find online is very limited, which is quite unusual for Parallax.
Am I just not looking in the right place?

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I wonder if this wire is hot...

Jon Williams

Part of our responsibility is to *practicalize* (I know that's not a real word) a product like the Memsic 2125 so that they can be more easily used by hobbyists and casual experiments. Not all of the signals on the device are easy to use, nor would they be in a typical application. I'm not sure what more could be done with our documentation -- there's really no reason for us to repeat the Memsic technical data since that is freely available. What we try to do in all of our documents that use third-party devices is show the BASIC Stamp user how to integrate that product into there projects. True, we don't show how to read the temperature output in the Memsic 2125 document, but we do give the experienced user enough guidance to do it.

Please let us know what we can do to improve any of our documentation. It's something we take a lot of time to do and attempt to do well.

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Jon Williams
Applications Engineer, Parallax

LoopyByteloose

Some of the pinouts are NOT connected. They can change the frequency to a faster one.
Parallax did not provide for that alternative.

It seems that you get enough jitter at the sampling rate you have. You will likely need to add your current reading to 5-10 previous ones and then divide by the number of samples to get a 'smoothed' moving average [noparse][[/noparse]like the stock markets moving average calculation].

This smoothed figure is more useful.

Try getting the original, primary documentation from Memsic directly. There are about 3-4 publications that explain how to use it. They include X-Y-Z axis readings from 3 Memsics combined and readings in a moving automobile on an incline. These articles will expand you vision of what it can do.

And yes, those little things are components [noparse][[/noparse]The future is shrinking at a very fast rate.] I am not sure if all of the recommended ones are on-board or needed.

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G. Herzog in Taiwan

Electronegativity

Hi Jon, The rambling nature of my question was due to the lateness of the hour and some strong wine.

Here is a more succinct version:

Do I need to create the manufacturer's reccomended RC circuit around the memsic I bought from Parallax, or is it already on the 6 pin dip board?

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I wonder if this wire is hot...

Brian Carpenter

It is ready to go. use some resistors beween the xout and yout and the basic stamp. it shows the hookup if you go to the memsic on the parallax site and look at the supporting docs.

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It's Only A Stupid Question If You Have Not Googled It First!!

Jon Williams

It's ready to go.· Another thing we have is information beyond the essential docs; you can download anything you need from the product page:

http://www.parallax.com/detail.asp?product_id=28017

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Jon Williams
Applications Engineer, Parallax

Electronegativity

Ok, cool.

I am using it with an SX chip.
If I set the internal pullup resistor to high, is that good enough or do I need an external resistors on XYout as well?
If so then what would be a good value?

Thanks for the help guys, that was really fast!

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I wonder if this wire is hot...

Jon Williams

The outputs of the Memsic are driven so you don't need to activate pull-ups. Just use PULSIN (or a custom routine) to measure the pulses from the Memsic.

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Jon Williams
Applications Engineer, Parallax