Introduction

This Wiki offers some guidance on the sensors supported by the various versions of UAVX and the intentions for future support with UAVXArm.

Recommendation to Upgrade to 40MHz Clock

The recommended clock rate for the UAVX PIC version is now 40MHz. Converting from 16MHz to 40Hz is a simple modification achieved by replacing the 16MHz crystal with a 10MHz crystal and re-burning the PIC with any 40MHz version of the UAVX firmware after which UAVPset can be used to load further 40MHz versions. Ken at QuadroUFO can also send you 40MHz PIC at a nominal cost.

See the 40MhzFirmware Wiki.

PID Update Rates

• 100MHz STM Arm - 500 Hz nominal for FastPWM ESCs. I/O bound at 1KHz
• 40MHz 18F2620 PIC - 500Hz with I2CESCs replacing HMC6352 with HMC58X3
• 40MHZ 18F2620 PIC - 250 Hz
• 16MHZ 18F2620 PIC - 125 Hz

Supported Sensors

Y is included and X deleted. 16&40MHz are for the PIC version of UAVX.

UAVX will fly with gyros only but and accelerometer is recommended. Compass and barometer are only required for navigation and altitude hold.

There is some argument that the analog gyros still have the edge over the gyros that use I2C/SPI comms. UAVXArm will support both as the current UAVX does.

Multi Sensor Boards

There are MANY boards out there that use some combination of the sensors above.

There will be many many more and my prediction is that the direction will be towards devices like the MPU6050 with sensor fusion math thrown in. Cross calibration of the sensors is a big deal and there are motivations ($s) to do this and motion tracking easily and cheaply.

A common sensor combination currently is ITG3200, BMA180, HMC5883L and BMP085. The MS5611 has some supporters but startup drift seems to be an issue. An MPX4115 proto by Steve (Kisssys) gives great performance. The MPU6050 has appeared in the FreeIMU. The MPU6050 gyro is functionally the ITG3200.

Sensor Board Orientation

There is currently almost no consistency by the various manufacturers in placing the sensors on the boards so their axes are oriented coherently. UAVX and all other FC codes have to map the sensor axes to that of the aircraft. For UAVX it is assumed the boards above are mounted components up with the board edge with the pins to the front. I place them on the bare area behind the current Acc. The 9DOF SparkFun can be mounted on the existing pins used by the current compass/baro but it is no longer the best option.

I don't have all of the boards so if the mappings are wrong tell me. Use the artificial horizon to see the roll/pitch angle is stable and moves in the right direction when you move the aircraft. If there is a problem I would need to know for pitch and roll right what the accelerometer values are and and what sign the gyro rates are. Pitch up, roll right and yaw CW should be positive.