I have assembled a new APM from the diydrones store and uploaded the newest code for Jan.3 (1.01).
When I have the APM/IMU installed in my Easystar, the PPM light flashes and the A B C light never go into a flashing state for calibrating the gyros. All of the airplanes control surfaces and throttle work normal but the ailerons have a twitch that matches the pulse of the PPM light.
On the benchtop, I have a BEC powering the APM with 3 servos connected. Upon powereing up, the ABC lights flicker as normal and the aileron servos no longer twitch. When I try to use my transmitter to control the servos, they work normal but after a few seconds of inputs the APM resets into calibration mode.
I've tested the flight sim and everything works on that end. My older APM works with the newest code from Jan 3rd just fine on the Easystar.
I think the issue may be bad firmware for the PPM Atmega328 chip but I wanted to run this past ever one before ordering an AVR programmer.
Yup Ch5 is on a 3 pos toggle - connected to in8 on the APM.
Bit worried about the lack of regulators in spectrum systems - do futabas have them?
My open circuit voltage on the battery is about 5.1V and when connected to the APM the voltage across the rails is 5.01
I hope that my APM is not damaged.
Yep, tried using the throttle (CH3) to change modes with no effect. - the onset seems to be related to current draw.
With one servo connected operation seems normal, with two it will grunt into life before tripping up and getting caught in a restarting loop. With three or more the result is shown here:
(I'll get a longer one up if you need but my net connection here is V.Slow..)
The APM will be fine on 5.1 vdc. It is when you start to exceed 5.25 vdc that you may damage the APM. A fully charged 4 cell NMHi battery can reach 5.6 vdc.
This being the case - combined with the large number of people used to running either unregulated 4.8 or 6V Batts or BECs set at 5.5 or 6V would it not make sense to incorporate a clamper (or crowbar) to protect the APM when powered from the radio electronics? Even just a 5.1 Zenier?
Good to see you are moving forward with your issues, after reading the battery / BEC chat that is going on here I'm concerned that there is no warning about the battery packs causing an issue, there is no way my Futaba receiver has a regulator to hold it at 5 volts, the Futaba systems are designed to use either 4 or 5 cells which means a max operating voltage of 6 volts for higher powered servos where more speed and torque is required.
It would be good to have an "official" what to do if you are not using a BEC and are connecting a battery directly to the receiver.
I have similar reset problems.
When I go to Stabilize mode after the first completed calibration process, if I roll/pitch the aircraft, the APM resets to the calibration process. It may continue to reset when calibration has completed.
My system is: APM v1.4 and IMU -h with 4 servos. The APM is powered with a 3 cell, 3000 mAh LiPo battery through a Castle Creations 10Amp BEC, The BEC 5 volts is connected at the APM servo rail.
The problem occurs when the XBee is connected at the IMU board per http://code.google.com/p/ardupilot-mega/wiki/Wireless. If I remove the XBee the system does not reset in Stabilize mode.
Note: I do not always get the elevator kick during the calibration process.
I measured the voltage at the servo rail of the APM board at 5.0 volts under all conditions.
I measured the voltage at the +5 pin for the Airspeed sensor and the XBee +5 pin. It measured 4.57 1st startup but went down to 4.48 to 4.45 during the Stabilize mode just before the reset. There is a 20+ millivolt of square wave at XBee rate in Stabilize mode just before the reset.
I found that the +5 pins for the Airspeed and XBee ports are NOT directly connected to the servo +5 rail.
With ohm meter leads connected one way I measured infinite resistance (with Cap charge indication) and about 120 ohms measured with the ohmmeter leads reversed.
If I power the XBee from the servo rail +5 volts I get NO resets.
Note to the developers: You guys are doing one hell of a great job on these projects. Thanks.
Irvin, thanks for the issue report. I've forwarded that to the hardware team and we'll see if we can figure out what's going on. Stay tuned...
I am not buying what Irvin has stated. I just meased the resistance between the power (5vdc) and GND of the the Xbee port and the Airspeed port on the IMU Mega and the servo rails on the APM and found the resistance to be ~0.4 ohms which not bad given the distance between the two measurement points. I believe that Irvin has a bad solder connection somewhere between the ports' power and ground and the servo rails. Has Irvin unknownly removed the jumper on the SJ1pads on the APM?
Just a thought.