Which pin of the arduino that the esc is connected to

#1

I was reading the SCH of the controeller board of 2.8 and I came up with a samll problem
The SCH indicates that the ESC_3A to ESC_3C is connected to J16A to J16C, but I couldn’t find which arduino pin that the J16A to C represent. Or are they directly connected to the brushless motor.

Besides, there may be a pwm wire of the esc that is connected to arduino so that I can adjust the rotate speed by using the code. So which pin of the arduino that the PWM sire of the esc is connected to.
I have already managed to make the motor rotate by using my own code but I am still facing a very wired problem:
Situation 1: I unplug the pwm wire of the esc from the controller board with other wires still attached and connect the pwm wire to my own arduino UNO. I then burn the code that is for the PWM signal to the UNO and power the ROV on. It turns out that the motor successfully rotate.
Situation 2: I didn’t unplug anything from the controllerboard, I just burn the code that was in the UNO to the controller board , I powered the ROV again but the motor didn’t rotate. And i don’t know why. I assume that my code has erase some original necessary code for the rotation
To better illustrate, a handdrawing is shown below:

pwm.jpg1280x960 27.9 KB

Any one can give me some advice
Many thanks.

#2

The five connections on J16 are the five pads to which the ESC is soldered- one for battery power, one for ground, and three for motor outputs. The labels ESC_3A to ESC_3C are for pins in the DB-25 connector. See the DB-25 connector pinouts on sheet 2 of the schematic.

Each of the three ESCs gets its servo input from a connection to the Servo Output block on the controller board, J20. Arduino channels D6, D7, and D8 are used to drive the three ESCs. See the upper right corner of sheet 2 of the schematic.

Hope that helps.

-W