I'm constantly loading and testing code and the power setup of the 2560 can be a bit of a pain. Mainly, the radio does not receive power because the Servo rails are only powered via a Lipo, which can be very dangerous. I never do anything but fly with a Lipo connected and I certainly don't connect one indoors. I'm just paranoid that way.
This hack will power the radio half of the servo rail with 5V from the APM's USB connection. The idea is to spilt the 5V rail into two halves. If you use an X-Acto knife you can easily cut the trace connecting both sides. I cut the ground rail in half as well, then used some solder to repair the bridge. Then I connected the 5v from the APM to the input side as indicated below. Now I can power the radio with the USB.
Comments
Hi,
I tried it and it resulted in a loss of GPS in the field. There was only like 4.35V at the uBlox, which might have been too little. Had to undo it again.
What I think we should really have for safety against unintended motor starts is a hardware or software kill of all PWM out signals. OK there are BLC that will give up listening after some time without signal, I know..
This is the way APM 2 works. For those using APM 1, please note the warnings and advice about removing the signal cable when plugging in a LiPo, which are throughout the manual:
Jason I had the Shottky diode on my APM damaged so Ive worked out what I think might be a temporary hack I can use until I get a new diode. Can you please take a look and let me know if you see any problems with this hack? It seem to work so far, but Ive not yet flown using it with all the gear hooked up. http://www.diydrones.com/forum/topics/missing-apm-board-component-d...
where is SJ1? I did this mod Dave and didn't unsolder anything. Just make sure you do the clean cut of the copper trace between input and out put side. I was using the ESC power and it worked fine but now I'm using a separate switching 5v 3amp regulator power supply.
Hi Chris,
Thanks a lot, that did it. I wonder why my board was not "factory default".... There was no sign that it was ever soldered. Well anyway it works now.
Regards
Soren
Soren: This is covered in the Troubleshooting guide.
Hi, not quite the same topic but related: How can it be that my APM1 does not power up or light any LEDs when powered from the BLCs when my friend's one does?
It runs OK when connected to, and presumably also powered from USB.
5V output from the BLC was verified with a meter, is OK. Also the plugs the correct way around (under both BLC and US power it will start its motors).
In the schematic (APM, not the oilpan), I see 4 different nodes with power on: +5V, +5V!, Vcc and JP17 Pin 2. I wonder which one is the USB one?
Both my own board and my friend's were bought completely assembled. Could there be a jumper wire somewhere that was omitted on mine? Is there a regulator between BLC power (which might really be 6V or more from some BLCs) and +5V?
Regards
Soren
When I posted the pic was wrong, but it has since been fixed :) Will be performing this hack on mine soon.
This hack works a dream Saves a lot of switching around of wires etc,
Glenn maybe your confused by the numbering of the pins. On the older APMs boards the first pin was numbered 0 then through to 7 which is the eight pins for in put and eight pins for output on each side. The newer APMs the first pin is now numbered 1 then through to 8. Just make sure the cut is exactly in the middle of the 8 pins on each side which ever the numbering is.
At the same time, you might want to update that JP1 *must* be unsoldered. I don't think that's mentioned.
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