Gyro Troubles

[SteveO]

I apologize in advance if this problem is hidden elsewhere in another thread; I couldn't find anything similar.

We have received our analog devices ADXRS150 gyro and wired up the pins real nice to a PWM cable. We made sure with a multimeter that our connections were good and there was no cross talk etc. We housed the wired gyro board in a small enclosure similar to the one used for the camera from Radio Shack, filled with foam (perhaps the problem is here?). Using the gyro code provided by Kevin Watson we were able to get some output from our gyro.

Letting the program calculate the gyro bias gave us a little bit of drift even clamped securely with a rubber clamp to a table. We used the averaging function to get our gyro bias (a value of around 6537 I believe it was) and with that we still get a little drift but it is certainly acceptable.

My problem is, that when we turn the gyro 180 degrees (or any angle for that matter) we do not see any change in the output that would indicate we have done so. Does anyone else have this problem or know what I am doing wrong?

[Mike Betts]

This may be a bit obvious but make sure you are rotating it on the proper axis.

[SteveO]

Originally Posted by Mike Betts

This may be a bit obvious but make sure you are rotating it on the proper axis.

Thanks, I think it is something obvious I am missing. I'm still not quite sure what the right axis would be, but when I rotate it on any axis (I've tried all directions) I don't get a reading that looks any different than when it is clamped to the table.

[roboticsjenkins]

I would like to see a simple wiring diagram for a gyro if it is at all possible. I have a gyro from the Kit of Parts from last year. I am looking for a wiring diagram for it if at all possible.

[SteveO]

Originally Posted by roboticsjenkins

I would like to see a simple wiring diagram for a gyro if it is at all possible.

Go to kevin.org/frc and download the gyro code, the readme explains how to wire it.

[roboticsjenkins]

The readme did not explain the wiring, it was only programming language which I have no clue how to interpret. I know I have to wire it to the analog input to get power pu on this Gyro it says nothing about which color wire is what, I am still scratching my head on what to do. It has a blue, green and white wire. I believe the green wire is a ground, however I do not know where the blue and white wire go.

[Rickertsen2]

Originally Posted by roboticsjenkins

The readme did not explain the wiring, it was only programming language which I have no clue how to interpret. I know I have to wire it to the analog input to get power pu on this Gyro it says nothing about which color wire is what, I am still scratching my head on what to do. It has a blue, green and white wire. I believe the green wire is a ground, however I do not know where the blue and white wire go.

I have never personally used this gyro, but you can find the datasheet for this gyro at http://www.analog.com/UploadedFiles/...ADXRS150_B.pdf . It will include a pinout.

----------------------- EDIT --------------------------------
You are obviously using some kind of demo board for this chip, bc there is almost no way to solder to it.
The dasheet for the demo board is at http://www.analog.com/UploadedFiles/...XRS150EB_0.pdf

It looks like you need to conect it as follows:
AGND AND OR PGND: connect ground
AVCC AND PDD: connect to 5v
RATEOUT: connect to input (sig)

In order to get better noise rejection, you may want to add some bandwidth reducing capacitors as described in the datasheet.

[SteveO]

I'm not sure what kind of gyro you are using. There is probably a spec sheet that either came with the gyro or is available online that will tell you what cable is what.

Even when I rotate as described I don't get a change. Has anyone been able to get an ADXRS150 to work?

EDIT: I apologize, I am using the demo board, I thought everyone would assume that lol

[Mark McLeod]

Originally Posted by SteveO

Has anyone been able to get an ADXRS150 to work?

Quite a few of us have used it for awhile.

Attach 5 wires total to the chip. Several of them combine, so you end up with three wires going to the RC. Look at the datasheet to see which pin is #1.

pins 8 & 12 = Ground
pins 1 & 13 = +5v
pin 2 = signal

[SteveO]

I don't believe I soldered anything to pin 12. Could this be my problem? I only had a total of 4 wires on my chip: Pin1 and Pin13 +5, Pin8 GND, and Pin2 rateout.

[Kevin Watson]

Originally Posted by SteveO

I don't believe I soldered anything to pin 12. Could this be my problem? I only had a total of 4 wires on my chip: Pin1 and Pin13 +5, Pin8 GND, and Pin2 rateout.

This is correct. You don't need to solder anything to pin 12 because it's internally connected to pin 8.

-Kevin

[roboticsjenkins]

Thanks Kevin for your help, it helped me a lot. I have been scratching my head trying to figure this gyro out for 2 and a half days.

[Kevin Watson]

Originally Posted by roboticsjenkins

The readme did not explain the wiring, it was only programming language which I have no clue how to interpret. I know I have to wire it to the analog input to get power pu on this Gyro it says nothing about which color wire is what, I am still scratching my head on what to do. It has a blue, green and white wire. I believe the green wire is a ground, however I do not know where the blue and white wire go.

Blue is the analog rate output
Green is ground
White is +5 volts.

-Kevin

[Biff]

Originally Posted by SteveO

Thanks, I think it is something obvious I am missing. I'm still not quite sure what the right axis would be, but when I rotate it on any axis (I've tried all directions) I don't get a reading that looks any different than when it is clamped to the table.

The axis of revolution is viewed from the top of the chip. Look at the top and twist left or right while bottom of device is on table. You can also check the output voltage with a voltmeter. expect the voltage to rise or fall from about 2.5 as the gyro is in rotation and settle back to 2.5 while not rotating. Noise in the system tends to make 10 bit math not that stable unless you code for limiting the drift and noise. I haven't looked through Kevin's gyro code for this year. These issues may already be addressed. Measurement are from testing we did last year.