Help me pick an accelerometer

torby — Tue, 03 Feb 2026 22:24:31 GMT

I've been playing with an MMA7660FC, but I think it's not the part I'm looking for. If it is, please correct me

I'm interested in detecting linear motion, and not so much rotational. The main thing I want to know, at least for now, is, "Is the thing going thataway or thisaway?" Of course, playing with the 7660 gives me lots more ideas.

Thanks,

Torby

Re: Help me pick an accelerometer

Smiffytech — Sat, 15 Dec 2012 20:06:15 GMT

This isn't my area of expertise, so I hope someone will correct me on the physics if I'm wrong: if an object is travelling along a plane at constant velocity, there will be no acceleration to measure. There will have been measurable acceleration to get to that speed, so you should be able to estimate velocity and direction based on PAST data - but there's nothing to measure otherwise, unless the velocity changes. However, if you add a solid-state gyroscope to the equation, when you are moving against the against the axis of the gyro, there is always something to measure.

I don't think I've seen a Freescale accelerometer & gyro in a single device - the only combined sensor I know of is the FXOS8700CQ, which incorporates an accelerometer with a magnetometer for 6-axis sensing.

So - if you were to grab a Freescale I2C accelerometer, you could also hang something like ST's L3G4200D of the bus too, and work with the combined data. Or use the FXOS8700CQ plus the L3G4200D for 9-axis sensing!

You can get mounted gyros from the likes of Sparkfun and SeeedStudio for prototyping purposes.

Hope this helps!

EDIT: this may help you, but it's way too mathematical for me! https://community.freescale.com/community/the-embedded-beat/blog/2012/03/29/degrees-of-freedom-vs-axes

Re: Help me pick an accelerometer

torby — Sun, 16 Dec 2012 01:01:32 GMT

Well, yes. In order to know velocity, you integrate acceleration, then don't interpret the results too closely.

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Help me pick an accelerometer

Re: Help me pick an accelerometer

Re: Help me pick an accelerometer