PSAS/ ThirdGenerationIMU

10-5-05 20:34 LV1b IMU design review: Pressure sensor will be left in the design.

The CAN bus had a four lines, pwr, grnd, and two data lines. the pwr line first come into the circuit and meets and inductor, and a few caps as a filter. There is also a small diode for "reverse polarity" protection.

The next block is the LP2951, it is a voltage regulator. Because its internal Vref (reference voltage) is not as reliable the Vref from the ADC is used to over ride. The Vref from the ADC is attached to the pos input on an opamp, with an appropirate filter attached to the negative feedback look

The three pole low pass filter on the output of the gyros limits the bandwidth of the device so the PIC an ADC can sample fast enough. The rocket was assumed to no exceed 800Hz rotation change (NOTE: gyros dected spin change not spin velocity).

Tim has evidence that the entire board has less then 1/10th of a degree change across it. This implies more temp sensors are not requied for online calibration of Gyro/ACC's.

The only reason the temp sensor output runs off to another board is that they ran out of channels on the ADC.