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
You could attempt to re-flash the 32u.... Sounds like you have been lucky so far :)
The firmware is on the downloads page for this.
Your APM seems to be fairly well hammered unfortunately.
If a 2.5, there is only a small zener, D4, to attempt to clip overvoltage but it is not designed to handle a serious overload. If lucky, an over-Vcc would allow D4 to crowbar Vcc until one of the fuses opened. Did the 'smoke' you mentioned come from the APM or the gimbal controller?
You are entering the territory where you may need to install pins to allow checking the programming. These are not normally populated on the late model APM. If the unit is wrecked, you can do no more harm and perhaps obtain more data.
-=Doug
The fact that JP1 was installed is not good, that means that you have put a high voltage through everything :(
I very much doubt that it is fixable. Sorry :(
Which input port?
Chances are you have fed 11v or so into the MPU via the signal wire, frying the main MPU.
It will still light up on USB as it is the 32u chip that connects to the USB, but as the 2560 may be dead, there is still nothing for the 32u to talk to..
Best suggestion, new APM :(
Sorry...
Quick question: What is the limit to the amount of amps that I can pull from an Output of the APM2.5? I would like to power two servos from one APM Output. The servos together pull around 6.5 amps (Stall Current @ Locked). These are the servos: http://www.savoxusa.com/Savox_SH1290MG_Digital_Servo_p/savsh1290mg.htm & http://www.savoxusa.com/Savox_SC1258TG_Digital_Servo_p/savsc1258tg.htm
That's great, now I can try RSSI, because ports A0,A1,A2 is already used for airspeed and attopilot and only port left for RSSI in mission planner is "mystery" A13. Now I know where they hide it :)
Doug,
Yes - interesting idea about the interactive graphic. Let's first define some criteria so that a higher percentage of the Drone folks can make use of it shooting for 100%. Your simplified schematic is a great start and most usefulf for the 10-15% of us that have some electrical schematic reading experience. It's the best I've seen in explaining the many ways that the APM 2.5 can be powered and not powered! This is becasue it takes the full schematic and weeds out the chaff that's of no importance to other than the electronic engineers. I would like to see it modified into a type of functional schematic that all the Drone folks can understand and use. I don't think it would take too much in the way of modifications at least at the first step that I propose. Although your schematic focuses on Vcc it should also include the 3.3V linear regulator that steps the voltage down for some components (Data Flash and others) but just a listing not electrical schematics. This is to stress the importance of providing clean power to the APM and what components will be adversely affected when not properly powered. And it must include the Power Module that ships with every APM2.5. Yes it must include all the external communications connectors too but we do not need a schematic just the name of the connector and the group of parts that supports this connector in laymans terms ie GPS. We must avoid terms like AT503B1610-MU simply replacing it with Data Flash which is shorter anyway. Avoid terms like UART, SPI_Mega and others that are meaningless to 90% of the droid group. In summary drop all electronics acyronyms in favor of laymans terms for these functions. Technical folks love acyronyms while laymen do not understand them!
Gary McCray, in the Documentation Editors group, is dong a fantastic job of writing explanations with some illustrations and pictures and this will go a long ways. You should take a peek if you have not already. But there are I would guess half that don't read at least with enough detail to pick up the power supply options and nuances to keep them out of trouble. Perhaps they read better after they get into trouble - our goal is to keep them out of trouble in the first place.
In my experience as business owner of a DIY install avionics in full scale experimental aircraft, the verbal explanation is requied but the functional schematic is by far best and is supported by the explanations. It is imperative to use the full schematic as the source document in making the functional schematics and you have done this nicely already. It is also imperative to get the functional schematic down to something all can understand and apply to their varied projects. Your simplified schematic is nearly there!
If interested I can help advise how to acomplish this (no art work required) using your existing schematic format. I feel it is first necessary to get the rules down. Modification of your simplified schematic is the best place to start to set these rules. Then if you have the time and want to continue the graphic (sounds fantastic to me) it would be quite a contribution to the Wiki and group in general.
I spend summers in the N Pacific with poor communications. Is there a way we can have a private conversation before I leave next week assuming you are still intersted? 480-588-6689 You have the technical expertise to do this - I do not.
Thanks,
Jim
Doug,
Craig Elder put me onto your "simplified" schematic and is the best "picture" I've seen of how power is distributed about the APM2.5.
I have suggested it be included in the new Wiki but it may be slightly too technical for laymen as it is drawn. Can it be simplified a bit without giving up much? Specifically the top row plus the USB is great and dropping the notes about the values of resistors and part numbers with more simplistic part notes such as resistor, zener etc. could that work? The fuse size 500ma is nice to know though and is understandable by all.
Could the lower part of the schematic showing the UARTs etc. be reduced to just one Vcc carrot and a listing in layman's terms the Vcc powered parts below the carrot ( no schematic for each)?
Just a thought at this point.
The linked to schematic is a bit fuzzy. Would a pdf output from Eagle be sharper? I sure would like a pdf for my files in any event.
Thanks in advance for your thoughts.
Jim
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