We are using the Xander driver suite v2.9 with RobotC 3.08. We are having a problem with the gyro values when the robot is not moving. When the HT gyro sensor is directly plugged into the NXT, the magnitude of the values read using HTGYROreadRot peaks around 0.8. When it is plugged into the sensor multiplexor, the magnitude of the values read using HTGYROreadRot peaks around 8.0, about an order of magnitude higher.

We verified that the gyro values are reasonable when the robot is rotating with and without the multiplexor. We used a fresh battery. We calibrate the gyro using HTGYROstartCal before reading its values.

Can anyone tell if this is expected behavior when using the multiplexor? If not, can anyone offer any debugging suggestions.

Thank you.

We saw something similar last year. Try sequencing the power-up differently. In other words, first try powering up NXT THEN the sensor MUX, and then vice versa. One of the orders eliminated the noise on the gyro.

That did it. We powered up the multiplexor first, then the NXT. Thank you.