PCA9685 power

[MilesMV]

So I am working on a project with an Arduino and a PCA9685 by Adifruit and I need some help. So I am using the PCA 9685 to power 16 servos, so it's going to be supplying a good amount of power. Here's where the problem is going to come in; I need to be able to power this off the ground (I'm making something that is gonna fly) and I don't think that rechargeable AA's Adifruit mentioned are gonna cut it. The input port for power is just a + and - port that takes male jumper cables. Adifruit said it could take 4.8v or 6v rechargeable batteries sold by hobbyshops. I did some research and figured out that it's going to be quite difficult to recharge these batteries, forgetting the fact that it could be dangerous(I've had a NiMh cell blow up in my hand before; however, it was just one of the eight). I'm wondering if there is a way to attatch or plug in a port to the PCA9685 that would take power from a 3000+ mAh 4.8v-6v battery that contains standard connectors that would allow me to unplug the battery and plug right into a NiMh charger.

[Wawa]

I think you have missed the fact that a PCA9685 can't/doesn't POWER anything.
It just provides the control signals for the servos.

Power (the 2-way screw terminal) is NOT connected to the PCA9685 at all,
but goes directly to the power rows of the servos.
On the Adafruit boards through a reverse protection mosfet, no mosfet on the clones.

Only power/signal grounds are shared ofcourse.

The power traces on the Adafruit/clone boards are rather thin. I wouldn't push to much current over them.
You can always connect power (and ground) directly to the servos.
Leo..

[TomGeorge]

Hi,
Welcome to the forum.


Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html .


Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?


Thanks .. Tom...

[MilesMV]

Hi,
Welcome to the forum.


Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html .


Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?


Thanks .. Tom... :)

Hi Tom,
Sorry about that, it was only until later that I realized this discussion was probably in the wrong group. I attached a picture of the hand-drawn drawing. I forgot to mention the fact that it is also going to be controlling 5 ESC's.
Thanks,
Miles

[Grumpy_Mike]

Let's face it. That is nothing like a schematic is it?

Can you try again please. A schematic shows where every connection goes and you groups of unlabelled boxes just doesn't convey anything to me.

[MilesMV]

I think you have missed the fact that a PCA9685 can't/doesn't POWER anything.
It just provides the control signals for the servos.

Power (the 2-way screw terminal) is NOT connected to the PCA9685 at all,
but goes directly to the power rows of the servos.
On the Adafruit boards through a reverse protection mosfet, no mosfet on the clones.

Only power/signal grounds are shared ofcourse.

The power traces on the Adafruit/clone boards are rather thin. I wouldn't push to much current over them.
You can always connect power (and ground) directly to the servos.
Leo..

Hi Wawa,
I understand that the PCA9685 only supplies control signals to the servos. From what I understand, the PCA9685's computer processor gets power from the 5v port on the Arduino. So from what you're saying, even if I had a power source, around 5v suggested by Adafruit, connected to the board via the 2-screw terminal, it still would not have enough power running through the small traces on the board to the power the servos. So from what I understand you think I should power the servos separate from the board itself as it cannot supply enough power/current through the small traces on the board to power all of the servos I will have running? Is this correct? Thank you for your response, I found it helpful.
Thanks,
Miles

[MilesMV]

Let's face it. That is nothing like a schematic is it?

Can you try again please. A schematic shows where every connection goes and you groups of unlabelled boxes just doesn't convey anything to me.

Hi Mike,
Sorry about that. I made a new diagram with all connections between every electronic involved. In case it was confusing understanding the servo section of the diagram, I made a diagram with all connections to servos and ESC's from the PCA9685. All servos and ESC's use all 3 ports on the PCA9685. I have attached all of the photos.
Thanks,
Miles

[Wawa]

Correct. You can power a bunch of small ~500mA hobby servos through the board, but nothing 'bigger'.
Your ESCs could have fatter power/ground wires for motor power, and thinner wires for signal/ground.

Adafruit's boards have a min/max voltage limitation on the power connector because of the reverse voltage protection mosfet. Clone boards don't have that.
Leo..