Where can I get the pin in "hal.gpio->pinMode(pin, value);"

I want to add code “hal.gpio->pinMode(pin, value);” into ArduCopter,but I can’t find the “pin”.So I want to know where to find the pin.
If you can help me, that’d be awesome. Thanks!

pin is as per your hwdef.dat definition of board in /libraries/AP_HAL_Chibios/hwdef/.
In general AUX OUT 1 is pin 50 , AUX OUT 2 is pin 51 and so on.