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Hey all.

This question isn't really Arduino specific, but sparkfun's user forums don't seem to have a "general help" area - so I figured you would be the best folks to ask.

I have a MMA7260Q accelerometer breakout from Sparkfun, but I can't seem to get it working properly. I checked out the datasheet, and Tom Igoe's tutorial. I was originally trying to use the acc. with my arduino, but when I wasn't getting the results I had hoped for, I hooked up the device by itself.

Below is how I connected the device to my breadboard:
VCC - 3.3V
GND - GND
GS1 - GND # for 1.5g
GS2 - GND # for 1.5g
SLP - UNCONNECTED OR GND #tried both

I then checked the output voltages for X, Y, and Z based on the common ground. No matter how I move, shake, or tilt the device, I only see a maximum of 1mV change (which appears random).

I have double, and triple checked my connections.
Is there something that I am missing here, or is it possible that I have a bad unit?
Thanks,
Tim
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Looks like SLP is active low - so by tying it to ground you are putting it to sleep.

Tie it to 3.3V and see if it's happier.

-j

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I tried tying the SLP to 3.3V with the same results. Here is a crude picture that attempts to show the basic setup. I am using a simple voltage divider for testing. In the picture I have the voltmeter connected between 'X' and GND.

Thanks for any info you can provide.
Tim

« Last Edit: May 04, 2008, 07:39:13 am by imagitronics » Logged

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Sorry, gotta ask: did you happen to hook the device's Vcc to the Arduino's 5V Vcc at some point?

I can't see anything wrong with your breadboard layout.

I guess it's possible that it is bad; just reading the outputs with a meter you should see 1/2 of Vcc while it's at rest.

-j

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I don't recall ever having connected the device to the Arduino's VCC connection.

I connected a Wii nunchuck using Tom Igoe's I2C library and that work's splendidly. I have ordered another accelerometer from Sparkfun. If the new one works then I'll know that my current one is bad. If this one doesn't work either, then it's likely something I'm doing wrong!

In the mean time, I can use the Wii's accelerometer.

Thanks,
Tim
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FYI. I ordered and received an ADXL320 and I'm happy to report that it works as expected. It's starting to look as though my first accelerometer was damaged.

Thanks for all your help.
Tim
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Hello.

I know it's a little late for you now, but I thought I'd mention that Pololu has a compact MMA7260QT 3-axis accelerometer breakout board.  It is especially well-suited for Arduinos because it has an integrated 3.3V regulator, which means you can power the 3.3V sensor directly from a 5V microcontroller without the need for any additional electronics.

- Ben
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Thanks. That's very good to know for future reference!

Tim
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