Evaluation Board Gyro

[LieAfterLie]

What exactly is the difference between a normal gyro and the evaluation board gyro? Can you do everything with the normal as with the EB gyro?

Specifically ADXRS150 and ADXRS150EB, as ADXRS150 is what you can get free in the KOP (and what we already have).
From Kevin.org I got "They all come in a package that's too small to work with, so it's best to purchase the evaluation board version of the gyro."

EDIT: Same thing for accelerometers, as I'm going to depend on the gyro, accelerometer and camera alone for autonomous.

[jgannon]

The evaluation board is a PCB with the accelerometer mounted to it, and maybe a few passive components, so you don't have to solder a bunch of tiny bits yourself. It's definitely a lot easier to work with.

[LieAfterLie]

How hard would it be to use the non-EB gyro? What exactly would you have to do to interface with it the same way as the EB gyro? And does its accelerometer completely replace the KOP accelerometer? (It's a 2-axis I think.) What do the passive components include? Are there any functional differences? And what exactly is 'easier to work with'? I really tried, I can't find anything definitive online.... Links would be just as appreciated as continued info.

Thanx in advance

[Joe Ross]

Originally Posted by LieAfterLie

How hard would it be to use the non-EB gyro? What exactly would you have to do to interface with it the same way as the EB gyro? And does its accelerometer completely replace the KOP accelerometer? (It's a 2-axis I think.) What do the passive components include? Are there any functional differences? And what exactly is 'easier to work with'? I really tried, I can't find anything definitive online.... Links would be just as appreciated as continued info.

Thanx in advance

Here is a link to the product page for they gyro from Analog Devices: http://www.analog.com/en/prod/0%2C28...S150%2C00.html

From there, you can find out a lot more info about the chip itself and the evaluation board, including what is included on the evaluation board.

The standard chip is packaged in what is called a ball grid array (BGA). The pads are located underneath the chip and are impossible to reach with a soldering iron. You need specialized equipment in order to solder a BGA.

[TubaMorg]

Definitely go with the evaluation board. It comes preassembled with the proper set of capacitors and other doo-dads that make it ready to use. Otherwise you have to read through the spec sheet for the gyro chip and figure out how to set up. Why bother?

[robind]

On the board that FIRST sent us, we're supposed to connect three of the pinouts to the analog inputs on the FRC. That was easy.

But we're also supposed to jumper something on the board. I'm a bit confused as to what exactly we're supposed to jumper. Can someone help me out?

[Jared Russell]

I don't recall having to jumper anything. It should work out of the box.

[TubaMorg]

Actually you do have to do a little wiring, it's still much easier with the eval board. Here's what you do (hopefully I'm remembering correctly). Below is the link to the spec sheet for the eval board for the 300 deg/sec model. Wiring is the same for the 150 deg/sec. Under the heading "Circuit Description" it sort of gives you clues to how to connect the thing.

http://www.analog.com/UploadedFiles/...XRS300EB_0.pdf

Mounting eval board:
1. Use a project circuit board from Radio shack. Doesn't have to be big.
2. Solder a wire from pin 1 to pin 13. This is your jumper.

Now you need to connect your PWM wires:
1. Black wire is ground, connect to either pin 8 or pin 12 as they are bridged in the EB.
2. Red wire connects to pin 1 or pin 13 (the same pins you jumped).
3. White wire is for the signal. Connect to the rate out pin (pin 2).

This is the simplest implementation and seems to work ok for us since we don't have any electrical engineers on the team. Further wiring can be done to help bias the output based on temperature and reduce noise, etc. but we found it to be unnecessary for the short duration of the competition.

Hope this helps a little!

[robind]

Okay, so I figured it was 1 and 13 on the diagram in that pdf (I actually already had that pdf open ), but I can't seem to figure out what that physically translates to on the board first sent us. Does anyone have a picture of their jumpered circuit?

[TubaMorg]

Originally Posted by robind

Okay, so I figured it was 1 and 13 on the diagram in that pdf (I actually already had that pdf open ), but I can't seem to figure out what that physically translates to on the board first sent us. Does anyone have a picture of their jumpered circuit?

Ok, I think we need some clarification. The 150 deg/sec gyro that FIRST is providing shouldn't require any jumpering. You need TWO pwms, one for the yaw rate signal, the other for temperature correction signal. The temperature correction is handy because the yaw rate gyro outputs a voltage (0-5volts) proportional to the rate of twist. At 0 deg/sec the output is nominally 2.5 volts. Temperature makes the 0 point drift up or down. So in competition it is possible that the gyro temperature may change and thus throw off the reading.

Now what I was talking about for jumpering is the Eval board you can order directly from Analog Devices, which is what the supplied link is describing. The drawing shows pin 1 and pin 20. The rest of the pins are numbered counter clockwise (looking from the top of the board, not the pin side). The EB has pin 1 printed on the board.

Uh does this help or make it even more confusing?

[LieAfterLie]

How exactly would you hook up the normal gyro and how impossible is it?

[robind]

Originally Posted by TubaMorg

Ok, I think we need some clarification. The 150 deg/sec gyro that FIRST is providing shouldn't require any jumpering. You need TWO pwms, one for the yaw rate signal, the other for temperature correction signal. The temperature correction is handy because the yaw rate gyro outputs a voltage (0-5volts) proportional to the rate of twist. At 0 deg/sec the output is nominally 2.5 volts. Temperature makes the 0 point drift up or down. So in competition it is possible that the gyro temperature may change and thus throw off the reading.

Now what I was talking about for jumpering is the Eval board you can order directly from Analog Devices, which is what the supplied link is describing. The drawing shows pin 1 and pin 20. The rest of the pins are numbered counter clockwise (looking from the top of the board, not the pin side). The EB has pin 1 printed on the board.

Uh does this help or make it even more confusing?

So do I have to wire all six pinouts for the one that FIRST provided to work? I only wired the "Twist" pinouts. And it wasn't working. Maybe I should wire up the other pinouts