APM2.5 5V/Vcc Schematic

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

APM2_5 Simplified Power.PNG

Peter has it dead on.
D4 is a 'last resort' protection of the APM Output lines in the event the BEC/Battery exceeds 6 VDC.

Vitaly, because it seems your D4 is damaged, even though a static Ohm test seems OK, your device may be doing the job at the wrong voltage. D4 is connected to the 'Vcc' line. 'Vcc' also supplies the 3.3V regulator for the logic families that use that power.

Things to do:
1) Remove the BEC/ESC input and check the power output that was connected to the APM. 5.1 VDC best!
http://code.google.com/p/arducopter/wiki/APM25board_Overview#Altern...

2) With BEC disconnected, connect USB and measure the Vcc value. It may be 4.75 to 5.1 VDC; depends on the PC and connection/wire resistance.

3) If Vcc is OK, APM should respond OK. If Vcc is very low.. less than 4.1 VDC, D4 should be *removed*. If Vcc OK (4.75 to 5.1 VDC), D4 was problem. If Vcc not OK, something else is bad.

-=Doug

Replies

Mike Mac March 14, 2013 at 10:07am

USB problem

When I connect the USB I get the flashing A and B led as they should. After a time they go out and the B led remains on solid and it won’t link to my computer. Any ideas on what to look for?

The LED status information does not list this condition?
Developer

Philip February 26, 2013 at 5:26pm

@R. D. Starwalt

can you add a link to Altium Schematics and PCB Files above, as it may help some members

Thanks

Philip
steve February 11, 2013 at 12:36pm

Is this the GPS connector housing? If it is then they have the 1x4 and 1x5 also for telemetry and power module.

http://hansenhobbies.com/products/connectors/150mm/150mm_1x6/

Hansen Hobbies - 1.50mm Connector Housing and Headers (1x6)

Hansen Hobbies - Electronics for Radio Controlled Aircarft
steve February 8, 2013 at 10:35am

I received it in December. It was when they dropped the price. It has the two gps connectors even though the ublox they sent with cable that goes on older port so Im not using the new gps port. I just need to make new gps and telemetry cables. Preferably the new gps connector but either will do. I think I found what I need at Hansen hobbies but wanted to confirm the type of connector.
steve February 7, 2013 at 3:15pm

I need to make some cables for the new GPS port and telemetry port. Does anyone know if this is the type of connectors it uses?

http://hansenhobbies.com/products/connectors/150mm/

1.50mm Housings and Headers

Hansen Hobbies - Electronics for Radio Controlled Aircarft
mack goodman February 2, 2013 at 8:58am

Simple question, but I cannot find answer here.

I want to use the AttoPilot 90A/50V Voltage/Current Sensor for the APM 2.5 and power it the same way I do the APM 2.0.

Do I use the same connections as I do for the APM 2.0? that is A1 and A2 for the voltage and Current leads?

thanks for pointing me to the answer..

Mack
R. D. Starwalt December 19, 2012 at 6:11am

Note: The 'Mystery Port' was revealed to be the connection for the new 3DR APM Power Module.

This schematic also works with APM 2.5.2.

-=Doug
R. D. Starwalt November 25, 2012 at 6:17am

Peter has it dead on.
D4 is a 'last resort' protection of the APM Output lines in the event the BEC/Battery exceeds 6 VDC.

Vitaly, because it seems your D4 is damaged, even though a static Ohm test seems OK, your device may be doing the job at the wrong voltage. D4 is connected to the 'Vcc' line. 'Vcc' also supplies the 3.3V regulator for the logic families that use that power.

Things to do:
1) Remove the BEC/ESC input and check the power output that was connected to the APM. 5.1 VDC best!
http://code.google.com/p/arducopter/wiki/APM25board_Overview#Altern...

2) With BEC disconnected, connect USB and measure the Vcc value. It may be 4.75 to 5.1 VDC; depends on the PC and connection/wire resistance.

3) If Vcc is OK, APM should respond OK. If Vcc is very low.. less than 4.1 VDC, D4 should be *removed*. If Vcc OK (4.75 to 5.1 VDC), D4 was problem. If Vcc not OK, something else is bad.

-=Doug
Developer

Craig Elder November 7, 2012 at 11:55am

Thanks for posting this Doug!

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APM2.5 5V/Vcc Schematic

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