broken gyro?

[hrldcpr]

hi all,

i think our gyro or some part of our gyro board may be broken, but i want to be somewhat sure before we try to order a new one.

here are some clues:

* the resistance between supply and ground on the board (when unplugged) is 8.7kΩ -- should it be higher? what is it on a known-good board?

* when i do plug it in (to the crio analog), the voltage between supply and ground gets pulled to -0.76V, whereas it should be +5V! (this number seems suspiciously similar to a diode voltage drop but i don't understand if or why that might be relevant.)


we're definitely connecting the power and ground and signal to the proper places. and the soldering checks out too, unless a very slight short could somehow be providing the 8.7kΩ path between power and ground?

thanks for any help!

[DonRotolo]

Originally Posted by hrldcpr

i think our gyro or some part of our gyro board may be broken, but i want to be somewhat sure before we try to order a new one.

Considering that "The gyro is unique and is not available for puchase" <sic>, you will need to buy a raw gyro and make your own support circuitry.

Your best bet would be to find a local team who can help. Sorry, we're not at the shop so I can't measure it.

Can you give us details on how exactly you have it connected?

[samir13k]

Just a quick thought, make sure that your analog breakout is functional. Ours had not worked for two days before we had realized that the analog breakout light was not illuminated.

we usually get gyros from sparkfun.com if we dont use the kit one.

[hrldcpr]

We just have it connected into channel 1 of the analog breakout, +5v to +5v, ground to ground, signal to signal. (But we've tried other channels too, and just powering it directly.)

The analog breakout is working as far as I can tell, i.e. it's definitely providing the correct supply voltage, though once we hook it up to the gyro board that voltage gets pulled negative which is obviously not good.

I don't expect there's a simple solution, just hoping for some electronics genius to realize that one of the capacitors on the gyro board is dead or something so all we have to do is replace that instead of getting a whole new gyro. But yeah I think we'll end up getting one of the sparkfun breakouts.

Thanks for your input!

[Alan Anderson]

If the only thing you're connecting the analog input pins to is the sensor board, I can think of no way for the power pin to get pulled negative. Has the board perhaps been mounted in such a way that some of its traces are contacting the frame of the robot?

Is the green power LED lit on the analog breakout?

[hrldcpr]

I agree that it seems bizarre for the voltage to get pulled negative, but that's definitely what's happening according to my multimeter: the voltage between supply and ground on the analog breakout is +5V before I attach the gyro board, but then -0.76V when the gyro board is attached.

I am doing all of this at a work table, i.e. none of it is mounted to the robot and the board isn't touching anything conductive.

The green LED stays lit on the analog breakout the whole time. I haven't checked whether the other supply voltage pins also get pulled negative, and unfortunately I'm not with the electronics right now.