BEI Gyro Accuracy

[John Gutmann]

I am hoping for Kevin Watson to chime in on this one. I believe he was around way back when.

I have a BEI gyro I am trying to use for a VEX robot. I wrote a program for it, but it seems to be in accurate. I am using a 10 bit ADC. with a 1khz sampling frequency. I have simply written a (de)accumulator program. This just cuts the ADC reading from 10 to 8 bits, and either adds or subtracts the reading depending on the reading. The problem is that it seems to be very inaccurate. I could be my program, but it doesn't seem to be. I turn the gyro slowly, 90 degrees, and then back 90 degrees. it will return to a range of +/-40.

**Not degrees, these are just raw values from the ADC!**

I have a defined dead band of about .2 volts at the neutral position. When I turn I make sure the voltage output is outside of the dead band. I check this using a DMM. The other weird problem is the dead band is at 2 volts instead of 2.5 volts, which is what it should be.

The analog reference is about 5.1 volts.

If it matters at all I am using at ATMEGA16 microcontroller, and programming it using a STK500 dev board.

Thanks for any help,
John Gutmann