Assigning parameters to a poti

Andy that's the way I think it works based on Thiago's videos from last year. Seem to remember him being able to see the adjustments. But you need the Xbee Wireless to do this effectively.

 

Thanks, Gary. I never did manage to program the Smart OSD to use the Xbee UART and make contact with MK Tool....

Andy.

 

Interesting, Dave. When I try and change the parameter in the Smart OSD software to use UART: Xbee Direct, I click Test, Apply -- and that, according to the documentation should write the setting out to the SOSD board. However, if I then do a Get, the Transparent UART port reverts back to USB.

What are you doing to make the change to Xbee/Direct permanent?

Andy

 

Don't do the get. Do the write and then see if you can connect MKTool. I'm not sure what version I am on but making any kind of changes to the settings on the OSD using the Xbee were fraught with errors and frustration.

 

OK. So there's no way of actually checking by reading the parameters back from the SOSD board.
I'll just do the change, Test, then Apply, then connect up the Xbee and see if I can establish contact.

I suspect the Xbee introduces propagation and timing delays (hence the problem with MK firmware updates) and that's why it doesn't work well with the SOSD changes either.

Andy.

 

Andy the setting on the OSD side that works for Xbee for me is set it to XBee and Direct on the Global Parameters Tab.

Steve I was able to control a Poti via the Radio. Example for GPS Gain on the Navi Screen I change the gain to Poti 7 (this one used to be used to control a camera from the FC board). Then on the channels screen look at Poti 7, default is channel 11, at least on mine. Since I have the MC-32 my first open channel was 14 so I entered 14 for the channel. After each of those two steps I did the Write command.

To test I watched the Channels screen. Moving my slider (same as a rotary) I could see the value change as expected on the right side bars. Also across the bottom of the MKTools screens you should see the 8 Potis listed, small green squares, with an = sign and a value. That appears to be the value that is being sent to the assigned parameter.

Now my warning. I can see the value of the Poti changing with my slider. What I don't know is whether the 85 I see assigned next to the Poti value is really transmitting and changing to 85% on the GPS gain value. So use this at your own peril.

 

Thanks. I'll see if that works any better.

And that's how I remembered it -- so you're left with the disquieting feeling of, "OK, now I've got it set where I want it, what number do I type in to replace the POTI number for the same effect? And I think that's the crux of Steve's (and my) question.

Andy.

 

Just a guess, and you would need to try it on several values, but if you had a value for a parameter that was 0-50, then I would look at the Poti= value and see if that is the range you see. With the GPS Gain that I tested the 85 value was just below a center point which would have been about a -15 on the standard servo scale of -127 to +127. Clearly some further testing/evaluation needs to be done.

 

It's not an unreasonable assumption. It assumes a straight line mapping of the POTI value to the "legal range of values" -- and it would be a bit perverse for that not to happen. I'm a bit under the gun on other projects for the next couple of weeks, but I'll make a note to download the 2.00 source code and see if I can figure out the mapping function between POTI range to legal value range.

Andy.

 

And here's the answer with help from Thiago Krause in Brazil.

My friend about the POTI question ….

You have to set the gain to a POTI (easy)

Then this POTI should be a knob on the radio …. (no difficult here)

Now the tricky part is knowing the value …..

Well , in the MKTools you have to choose FlightController or Navi Controller (mouse click)

Wait for the infos to appear in the middle screen …. ( the green one that looks like a Cell phone from the 90's)



Then using the arrows , (right arrow to be specific) (For GPS Gain, click the Navi Ctrl button and then right arrow to screen 4. The value is shown next to the G)

Go and look for the parameter you are changing … like GPS GAIN ….. then rotate the KNOB , you will see the vale changing

Easy !

Just a tip … be careful , when using a Knob … each click ….. means like 7 points ……. its not 1 Click … 1 point !

So be careful !

In my example above following Thiago's advice I dialed the gain up and down. GPS Gain appears to have a value of 0-250 which happens to closely coincide with the values for a servo -127 - +127. So if I centered the slider the value shown was 126. With the slider adjusted so that I saw a 70 value the Channels tab looked like this for the value of the Poti 7.



And finally I was using an Xbee wireless which means in real life I could setup my laptop, get my setting adjusted, click write, fly a quick test flight, land, make another adjustement, write and do it again.

You could also do the more adventurous route by making adjustments in the air but one slip could lead to disaster.

 

And don't, whatever you do, write any settings to the boards while you are airborne as that resets everything and the copter will drop out of the sky. Or so it is said.

Andy

 

Yeah. I was thinking Gary was omniscient....