Frequently asked questions are about powering an APM2.5 or why the same does not work or why it has failed.
Here is a simplified schematic showing the major components of the 5V/Vcc circuit on the APM2.5
Target Audience: Readers who do not have Eagle or are confused about using it.
You Need: Basic electronic schematic reading ability
Note that I have separated the PWM Output section into the upper left corner with a heavy purple line that is bridged by the jumper JP1 on the APM2.5. This is to emphasize that diode D1 passes current through JP1 (and drops voltage). The remaining energy is then called 'Vcc'. Everything outside the purple corner is Vcc.
This is why the USB will power the APM2.5 when connected to a computer/USB hub. Note the fuse on the APM2.5 side of the USB connector AND another fuse on the output of D1. Another change from APM2.0 is the D4 6.0V Zener diode. If an over voltage is applied to the board, D4 will crowbar what it can to protect devices.
As with APM2.0, any 5V source connected to any of the indicated Vcc/5V points outside the purple corner (with GND of course) will power the APM2.5.
Also of note is the 'Mystery Port'. This port takes 5VDC before D1 and the fuse and is called 'JP_VCC'. Other clues to the mystery are the lines to 'ADC 12' and 'ADC 13'. A mystery indeed!
Any errors in this drawing from editing are mine.
I hope this can be used as reference for solving problems.
-=Doug
27-FEB-2014 Eagle files are now located HERE
Replies
Which part burned?
There have been reports of the small cable from the PM to the APM burning, usually the ground/earth wire.
You should suspect F2 is open.
Take care with the wiring to follow the recommendations in the documentation.
-=Doug
Hi, could someone possibly help me with an error I'm getting or at least point me in the right direction as I'm kind of new here.
I have APM 2.6, gps, x8r, tinsy, on a tricopter (servo powered from separate UBEC)
Data logs report VCC fail, 4.6 v to 4.4 or less...
But when testing with a multimeter it reads the voltage as it should be, 4.85 or a bit higher...
This would appear to be a problem with something in the board that senses the voltage, is it ok to keep using the board or will it likely shut itself down if it thinks its not getting enough voltage?
I am new to electronics but I have soldered small things before, is it possible to replace the faulty voltage sensor, anywhere I can get more info on this?
Thanks very much for any advice
Ok so I test with a new APM2.6
VCC now reads correct with all other setup the same as before. Must have been a fault on the board or chip?
Also the fault I had with Lipo volt reading was caused when I tried to calibrate it selected 'other' in the options. This time when I set it back to 3DR it worked mostly. Its reading may be a fraction off but not much.
Did you sort out the issue with the bad APM?
I just reread the above post and *10* amps is a lot of current with no motors turning!
The APM should only draw milliamps when simply powered up.
There are several components that, if failed, could make significant shorted supply conditions.
-=Doug
It probably means your UBEC voltage is sagging under load from the servo. I'm assuming you are powering the servo with the same UBEC?
The voltage sensor is actually built into the AVR chip, so its unlikely to be faulty without it not working at all.
thanks for reply but not sure we understand each other.
My APM 2.6 is powered from the Power Module that supplies 5.3v, servo is powered separately from a 5v UBEC.
Its the APM that is giving errors regarding low voltage, and the APM that I checked with a multimeter to be in the normal range.
I haven't actually checked the UBEC servo voltage, as I didn't think that was an issue.
Now I have also the main battery voltage sensor and current meter not working, I have 3 Power Modules I tested with but all give same results so the problem must lie elsewhere.
The Current reading is showing 10 amps even when nothing is happening, I try to calibrate but then it just gives the figure I type in permanently.
Same with LiPo Volt reading, it just reads whatever I last calibrate it to.
Now my tricopter wont start, presumably failing the preflight VCC test, although I'm not sure, because when I test it when connected to a computer it reads a higher VCC and does actually ARM then, so I dont see the error message, I am just assuming its coming from that.
Also it mostly does ARM when in the house but often not outside, maybe the low temperatures are affecting a sensor?
I dunno anyway, guess I have to buy a new APM2.6 but I would like to know whats going on if anyone has any advice. thanks.
Hi all,
I have a question that's bugging me.
In some places including arducopter site (compassmot specifically) it's saying we CAN connect both BATTERY and USB at same time
In a case where I use a power module and no JP1 installed is this true or not ?
Thank you for your question.
If everything is wired correctly - we have seen many cases where this is not true - having battery (to power module) and USB should not harm anything. It is discouraged because the ESC are then powered and if you are working via USB to the APM, testing system parts, we certainly do not want the props to spin up.
The USB port is fused. I wish there was a power removal jumper for the +5 but, Pixhawk is the future and this entire thread may one day be retired when the hardware is no longer supported.
-=Doug
I have this weird problem with apm 2.6 power supply related!
These tests, Rx Connected to apm input rail, 3.2 FW, Quad config.
1) 5v analogue ubec connected to apm output rail, JP1 in place, measured input rail 4.4v
All functions work, arms, motors run for about 5 secs, varies in speed and then cuts, one blip of the
throttle, then returned to low and won't run again without rebooting!
2) as (1) above, but with USB also plugged in, works fine, input rail 4.67v
3) 5.01v analogue ubec connected to apm input rail, arms but immediately resets. Blinking led
4) As (3) above, but with USB also plugged in, works fine, input rail 5.05v
5) APM power module connected, won't arm, input rail 4.8v
6) APM power module connected, but with USB also plugged in, works fine, input rail 4.83v
If you follow the above tests, it doesn't seem voltage related, but appears that the usb supplies a part of
the circuit that the other supplies don't, Anyone care to comment?
The esc's are not the cause, have used them on many previous UAV's. This is about not arming, and occasionally arming then immediately resetting (not armed), There are no pre arm check problems showing, when connecting the usb, I'm not opening MP, just using the laptop USB v supply...
-
5
-
6
-
7
-
8
-
9
of 15 Next