SparkFun Forums

[ryan]

hi
what value for the X and Y filter caps should i choose to get any useful work from ADXL202.is 0.1uF OK ?

[leon_heller]

hi
what value for the X and Y filter caps should i choose to get any useful work from ADXL202.is 0.1uF OK ?

That's what I used on a little PCB I designed for it. It does depend on the application, though.

Leon

[ryan]

hi
what value for the X and Y filter caps should i choose to get any useful work from ADXL202.is 0.1uF OK ?

That's what I used on a little PCB I designed for it. It does depend on the application, though.

Leon

what if i want to use it an a tilt sensor for the RC plane or in the IMU ?

[leon_heller]

hi
what value for the X and Y filter caps should i choose to get any useful work from ADXL202.is 0.1uF OK ?

That's what I used on a little PCB I designed for it. It does depend on the application, though.

Leon

what if i want to use it an a tilt sensor for the RC plane or in the IMU ?

It works OK as a tilt sensor with those values, so it might be OK for the plane.

Leon

[ryan]

i have another question about accelerometers. if accelerometers can do the job of tilt sensors then why do we need Gyros ?

[leon_heller]

i have another question about accelerometers. if accelerometers can do the job of tilt sensors then why do we need Gyros ?

To measure angular rotation.

Leon

[roach]

To measure angular rotation.

Is that the same as "turning"? Like, if my plane (or robot, or whatever) turns left or right, and I want to know the exact angle that it turned, I would use a Gyro, whereas if I want to know linear acceleration (and by extension velocity), I would use an accelerometer.

Is that correct?

[leon_heller]

To measure angular rotation.

Is that the same as "turning"? Like, if my plane (or robot, or whatever) turns left or right, and I want to know the exact angle that it turned, I would use a Gyro, whereas if I want to know linear acceleration (and by extension velocity), I would use an accelerometer.

Is that correct?

Yes, finding the angle the plane is turning through.

Leon

[Philba]

on the filter cap - the datasheet is quite detailed on tradeoffs of filter cap size. .1 uF is a reasonable choice but does affect measurement bandwidth. I got a bunch of 202s from surplused game controllers and they had .47uF caps on them. I assume this was to keep the noise low - pretty slow 10 hz updates though.

by the way, this was an incredible bargain - $1.50 (iirc) for each controller. the 202 was mounted on a little daughter board. lots of other nice scounging parts as well. too bad they are all gone, wish I'd bought more than 4.

Phil