Alternative gyros for the Mikrokopter flight controler v.1.x

[Arthur P.]

I have two defective yaw gyro's. I-ve already ordered a couple of new ones. But it is a pain. And then I came accross the following threads in the MK forum:

Using the ADXRS300 (http://www.Sparkfun.com/): http://forum.mikrokopter.de/topic-2252.html
Using the MLX90609-R2 (http://www.Sparkfun.com/): http://forum.mikrokopter.de/topic-4225.html

Although these are much more expensive than the Murata's they may be a bit more robust. In addition, although you need to bring the analog output voltage down to about 3V, you don't need the opamp and the additional calibrating resistors on the FC PCB anymore. You connect the analog output to the ADC pin of the processor (or correct output pin of the opamp pads after removing that).

In the 2nd thread he is actually using a mix of the Muratas (roll and nick) and the MLX (yaw). The first thread does indicate that due to the orienation of the gyro's he chose, he had to change the firmware to expect the roll/nick gyro vectors to be the opposite from normal. But if you choose the right orientation I expect this won't be needed.

So I have one FC where I-ve never been able to get the yaw gyro to calibrate properly, probably because it's a dud. In other respects that FC seems fine. And I have three of the mentioned breakout boards lying around (intended for an ARM7 project I just don't have the time for at the moment anyway). Logical choice: remove all Encata's, and the opamp, make a little prototype board for the MLXs, and connect the analog outputs to the correct opamp pads. Won't be today, more likely 1-2 weeks from now, but I-ll post pics and further updates once I-ve managed to find the time to do this.

[Arthur P.]

Well I have one Mikrokopter flight controler with three Sparkfun MLX90609-R2 gyro breakout boards working on the testbench.

This was really easy:

I delegated one flight controler to testbench status as I can't get the eeprom to reinitialize and thus can't change parameters or parameter sets. Removed the three Murata gyros (trashed one, but one other ended up replacing a defective yaw gyro on another board and thus getting that flight ready again). Then I did the following:


connected Vcc to +5v, (Note: do not connect Vref to 5V as Vref is an output)
connected GND to GND,
did not use the TEMPerature output,
removed the caps and resistors which connect to the opamp output pads, C17, C9 and C15, and R10, R14, and R18 (left C28. C29, and C30 in place))
disconnected the respective opamp output pads (1, 7, and 8 )
connected are only using the RATE output, after the reduction to 3V using the attached circuit (used wired parts, could easily be put onto a small breakout board), to feed directly to the correct processor pins (or the corresponding opamp pad: on 644 nick=35, roll=36 and yaw=37, opamp nick=1, roll=7, yaw=8. I actually used the pads of the removed resistors/caps as connection points


I now have three operational gyros showing curves in the MKTool. I still have to work out the correct positioning of the gyros to get the correct directions, but halfway there.

[brashley]

Hi Arthur, How are these working for you. Do you hapen to have a picture.

Richard