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
Hello,
I think I have tracked it down to a level shifter.
Cut the track on the vcc side of the TXB0104 and and checked the pad of the 3.3 and the volts was 0 volts, so I soldered the new regulator in and connected usb got 3.3 volts happy face.
but wont boot up just get red led next to usb LED7 I think.
maybe due to the TXB0104 going bad.
I had heard about another problem with a level shifter. It was many months ago and I cannot remember the symptoms.
Keep at the effort. Your work will help someone else I am sure.
Well done.
-=Doug
Hi every one. I am newbie to Arduino, APM and all this stuff. Are there any way to connect xbee directly to APM2.5.2?
Can i use APM GPS port for it? I checked the schematics and seems ok. What is the purpose of 3.3v regulator in the APM2.5? It seems i can get 3.3v supply to Xbee but not clear about the voltage levels of TX and RX. Do i need a level converter ? I need to test my Xbee S2. For the moment i don't have breakout board and cannot have in the near future. I do not want to connect any other modules only xbee s2 and APM2.5.2 for a small experiment.
Sure?. May i know the purpose of that 3.3v regulator. I read somewhere that xbees use very small current. Also found some schematics show xbees directly connected to Arduino.
i'm currently using APM v2.6 for my quadcopter. i have set the flight mode to stabalize and i powered up the copter. i was also able to arm the board (and the motors started to spin). but later even for the full throttle the copter is not able to take off the ground. i kindly request someone on this forum to help me out to fix this issue. plzzzzzzzzzzzzzzzzz
thank you
Shashikumar - wrong spot for this question but, my initial opinion is your ESCs are not calibrated properly with APM.
The calibration can be tricky at times depending on your ESC and TX.
This does, of course, assume your motors are spinning in the correct direction for their assignments and that your propellers are on the correct motor and mounted in the correct up/down orientation on the motors.
-=Doug
Yeah that's right. After that I used a spare cable but didn't power up. I checked and pm gives out 5.4 v. Please note that I can power up apm using servo rail output.
There is a subtle difference between '5V' and Vcc in APM2.6.
5V is defined as the connection at JP3 ---> JP1(closed)---D1---F2--- then it becomes Vcc afterward.
The PM supplies JP_Vcc----JP1(open)---D1---F2--- same as above.
If JP1 is closed (jumper in) and a PM is used, the risk is potential voltage/current mismatch from the ESC/BEC and PM. They share a common ground(earth) and this is usually the failure point with the wire overheating and the insulation melting.
Another method is to simply remove the BEC output wire from the ESC. This way no mismatch can occur.
The condition does get your attention quickly. ;) :0
-=Doug
hi guys,
I'm using apm 2.5, hk esc with sbec, apm power module.
today while testing motor and servos, somehow the PM cable burnt to ashes. i suspect esc because motor was running at the time. PM was quite hot. Then i removed esc and use another cable to check PM and apm dosent power up.
but when i check with esc bec it works fine without problem.
i then checked output voltage from PM while connect to apm which was around 5.3, but it dosent power up.
apm works perfectly with usb and bec.
what might be the problem? brownout fuse or esc?
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