Ardupilot 2.8 will not arm after esc cal

Seem to be stuck with similar but different symtoms on parallel (first time) build. Tried everything I can find online here (and other sources) including reinstalling firmware. Basically after esc calibration the motors run OK but when power cycle to Ardupilot and reconnect Mission Planner nothing happens. No red alarms on HUD or messages to give me a clue. Subsequent power cycles cause motor controllers to either beep slowly or quickly with no apparent rhyme or reason. Any suggestions?

Can’t believe it, stick was backwards! Thought something looked funny on the radio cal, the graphs should move in the same direction as the stick, duh. Now to figure out everything I changed in the troubleshooting, maybe easier to re-flash and start over…

I take it that by “stick was backwards” you are referring to the throttle stick. Is that right?

I have a similar end problem: the motors won’t arm anymore. They did arm several times prior to my attempting to change the MOT_SPIN_ARMED parameter from value 70 to value 30 (in order to cause the props to spin much slower upon the motors being armed than they spun while that parameter was at value 70.)

That is the only thing I changed, by first making the change in Mission Planner’s “Config/Tuning” - “Full Parameter Tree” - “Mot” - “MOT_SPIN_Armed” routine. I then selected “Write Params”, then “Refresh Params”, and, after that, I tried to arm the copter. All I got was a slight shudder from the motors (all at the same time), accompanied by a solid red light on the APM (for all of about one second).

Ideas from anyone would be greatly appreciated.

Copter: 550 Hex
FC: APM 2.8
TX/RX: Turnigy 9x/Turnigy 9XBC V2
Firmware: A.C. 3.2.1
Props: 9" Nylon
Motors: Turnigy Prop-drive 28 26-28
ESC: Turnigy Plush 30A
Battery: Turnigy 5000 mAH 30-40C 4S Li-Po
Compass: Ublox Neo 6-NM on a 6" pole

Rudder (and aileron) sticks were backwards. Apparently they need to be reversed on Spektrum radios for Ardupilot. Throttle trim happy at null too, not full negative as some posts suggest. Still very much on the learning curve so can’t offer any suggestions but thought it worth noting as didn’t find this info in any other post…

I think the obvious would be to set it back to 70. It’s possible your ESC’s can’t throttle that low.

I’m with you on that idea. Right after this happened I immediately re-set MOT_SPIN_ARMED back to value 70, saved the file, and uploaded the file back onto the copter.

Another attempt to arm it was made - same reaction - the red LED momentarily went solid and the motors gave a little stutter. Then the red LED went back to flashing and the motors didn’t respond at all to my advancing the throttle.

Did a radio calibration right after that - no problems there.

The copter was shut down, I unplugged the USB, and hooked the battery up and tried to arm again - no joy.

I plugged the USB back in and checked to see what it showed the value for MOT_SPIN_ARMED was - it was 70.

I think my next move is going to reset the EEPROM and reload the program onto it - after I go thru the configuration settings again just to insure they are all within parameters.

Did MP say it just wrote just the one param? That is very strange. I’ve adjusted motor idle speed from zero (not turning at all), to the stutter point, to fast and faster and never seen that.

Well, I have finally got the APM to arm, and I even get all motors to spin upon arming. I found that they won’t spin at anything less than a value of 60 in the MOT_SPIN_ARM parameter, and that you can set them to as high as 150 (I did that - it works) - but I didn’t go any higher. I’m okay with 60.

I don’t know what I did to get this to arm - I’ve been noodling about in the parameters tree trying this and that, and I didn’t keep accurate records as to what I did at any time. But, suddenly, it now works.

This evening I was able to get my HUD compass to finally show 350 degrees when the arrow on the flight controller was pointed exactly at true north. Heretofore the compass heading was showing somewhere around 22.25 degrees in those instances. I checked COMPASS_DECLINATION and found it was set to a value of .006. I twiddled around with other values and found that .395 nailed the compass heading to 360.00 degrees. Success! After a couple of frustrating months!

Now I just need to get the motors to speed up and slow down when I move the throttle stick!