@mosum, I think that was a firmware issue or bad calibration that you done before.
Try these steps.

reset parameter to defaults from advanced parameters menu,
Disconnect and reconnect power (USB/battery)

While disconnected in mission planner goto initial setup
Click wizard and complete all the steps.


Edit:

If the problem still persists then that should be a hardware problem and the voltage regulator in apm need to be replaced.

@akhilzid...
 Finally i have done all the calibrations successfully including RADIO CALIBRATION.....It happened when I changed my mission planner version from 1.3.24 to 1.3.30.......RC calibration done with ACRO mode in Tx....ESC and all were also done....but NOW

NEW PROBLEM : What to do in Tx to fly my quad....its not getting up and instead when I use throttle it goes to one side....cant make it fly.....should I change the flight modes ?? Or should I change anything on the Tx ??

Most probably the THR_MAX value is 80. See http://www.rcindia.org/multirotors/building-apm-2-52-quadcopter-with-st360-kit/msg232996/#msg232996

But now mine gets up and flips over. I'd check that issue next. If yours flip to the other side even after changing throttle max value, you have to troubleshoot that.

In crease Thr acc

How to troubleshoot that?

The probable issues are mentioned in the arducopter wiki. The URL is in the link
http://copter.ardupilot.com/wiki/common-appendix/troubleshooting/#Copter-tilts-flips-over-or-wobbles-crazily-when-I-try-to-take-off

Have you tried taking off with the stock values? It will be easier to help you if you can provide details about your frame size, weight etc.

It's not a Tx problem. Remove the propellers and arm the board. Then check if the APM points in the right direction and the motors are moving as shown in the attached picture.

Good to know that you solved the radio configuration problem! 

hello everyone, I have done all the calibrations successfully. I have checked motor movement accordingly and connections correct. Just unable to fly the quad. One side goes up and other down. cant fly. What to do

Maybe the CW and CCW rotors have not been attached as per the diagram. Or, like it happened in my case, mismatched the output of the APM with the wrong ESC motors. I don't know if that is your case but you can check that but my quad flipped over due to that problem.

mousum - take off your props - hold the quad in your hand and tilt each axis

when you tilt towards any particular axis - the motor going downwards should speed up and the
opposite side motor should slow down.


when you have the above checked and corrected . put on your props in such a way
that the air is blown downwards for all motors ( this may sound obvious ) but this
is a very common mistake by beginners.

do the above and confirm that all is ok . and if it still does not fly . we can advise further.

CW and CCW motors are properly connected as per the diagram. Still flipping occurs.

Ya I did that..but results are negative. The motors downwards are not speeding up automatically. What to do next ?

post a picture of your quad
and a close up of the control board wiring .

Here are two pics of connections....

wiring seems okay -

refer to the pic above posted by swapnil - unplug all your motor/esc plugs
and then plug them in one by one and see if the correct motor responds.
i.e
plug one (all other slots empty ) - front right motor should run
plug two (all other slots empty) - rear left motor should run

and so on

before doing all this I trust you have selected the correct config in
mission planner ?

I once had the same issue(flipping right after throttle ~40%). For me it was caused by a misaligned compass and accelerometer. Arm the copter and give just one step of throttle, enough to spin props at some speed. Lift the copter in your hand and tilt it sideways/front-back and see if the stabilization works okay: it should apply more throttle to the lower level motors and less for the higher motors, if not the board isn't aligned correctly w.r.t motors. Also see if the GPS's front points to the APM's front. Another time it happened, it was just in tuning mode and I forgot to take off without a gps lock.

Re calibrate your compass and accl after each firmware update(some even require it) btw.

Ya I did that,,,worked properly. But still cant make it fly,,should I go to a open space or it flies from a single point ??

Depends on how balanced and trimmed your copter is, you can do this in a fairly large hall or your backyard. DO NOT tune indoors, ever. The turbulence/propwash is too damn high inside.

Please let me know what is to be done with transmitter settings for the first flight...if someone really did this tell me in details....give me a summary of first flight setup,,please

I did not do much transmitter settings, Whatever I did is available in the videos posted in the following posts:

http://www.rcindia.org/multirotors/building-apm-2-52-quadcopter-with-st360-kit/msg231083/#msg231083
http://www.rcindia.org/multirotors/building-apm-2-52-quadcopter-with-st360-kit/msg231117/#msg231117

In addition, I had to reverse the throttle and pitch channels as the direction was opposite to what was desired.

I did not set pitch curve etc. Those are not essential for getting the quad to fly. I'd probably do that when I understand the effects better.

Doing tuning right now, with a new build. I did nothing but calibrate the ESCs, RC calibrated with APM Planner and set my primary flight mode to stabilize, second on alt-hold and third on land. Channel 7 was set to turn on Auto Tune as well. Trims on transmitter were set to 0, plugged everything in and tested all motors etc. Put flight mode switch to stabilize.
Hold arming position for about 15 seconds to start in auto trim mode. It should start up and fly properly if everything is in order.

The process is well documented in their wiki site and there's an 8 part youtube video series on it as well.
I am also afraid that it might be faulty parts? Have you checked if all sensors are working, no interference etc?

mosum - just verify that the motors are connected to the right port in the apm - that
is most essential . transmitter setting will come later. if the motors are not speeding up when
the arm drops then no amt of settings will help you.


@santanucus - pitch curve is applicable to variable pitch rotor or propeller - like a cppm
helicopter. it is not applicable for a multirotor. ( at least not your one)

Oh I didn't know that ! But I think I saw some videos where people have been changing the pitch curve for multirotors. I'd double check what its all about.

By the way, any idea why till 50% throttle my quad does not gain significant height? And only after 50% it begins to rise higher? Do I need to adjust throttle curve or something? Or could there be other reasons? I have a CX-20 and a Syma X5C-1 and in both cases the quad gains significant acceleration upwards even before reaching 50% throttle.

@santanucus

I guess you know this, but an APM multi-rotor is sopposed to achieve a stable hover at 50% throttle. If your quad hovers above (or below) 50% throttle you need to decrease (or increase) the 'throttle_mid' parameter. Don't change the throttle curve on your transmitter.

Try this, if you haven't already:
http://copter.ardupilot.com/wiki/ac_throttlemid/

Using pitch and roll curves makes the quad less sensitive around the middle stick position. This helps while landing or trying to get a stable hover.