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
Is it not then advisable to have a separate supply maybe 3.3 v to the board to prevent this type of failure . my board doesnt communicate "connect" to the mission planner I notice just above the silkscreen IC2 a pin hole in that diode marker ..I guess...3.3 ???
do you think further damaged could occur ???
I cannot connect any longer APM 2.5 to Mission Planner Board is recognised baud rate set ok but Times out
No Heat spmething message
I notice that the diode just above the IC2 socket has a small pin hole maybe blown yet seems ok with multimeter
any one with the full schematic
I think the ESC calibration caused this connect disconnect Lipo send spikes all over the board especially with jumper JP1 on it would be better to power the APM with a separate supply no ? Am I wrong??? help
Thanks for posting this Doug!
Thanks again for helping to clear up and simplify/de-mystify potential questions.
Tim
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