Click images to expand
The crossing gate is pretty straight forward and the process should work for most any crossing gate that has a 'T' like structure . It's probably a good idea to play with the servo before attaching the connecting rod.
PCA9685 datasheet: [click here]
When a LOW level is applied to OE pin, all the LED outputs are enabled and follow the output state defined in the LEDn_ON and LEDn_OFF registers with the polarity defined by INVRT bit (MODE2 register).
When a HIGH level is applied to OE pin, all the LED outputs are programmed to the value that is defined by OUTNE[1:0] in the MODE2 register.
Drill a hole in the crossing gate, see 2nd image
Mount the crossing gate to the top of the board
Mount the servo directly beneath the crossing gate. Options:
3d printable bracket [click here]
Run a push rod from the servo to the crossing gate.
Schematic: [click here] It may look better if you download the image to your computer, then open it with your favorite picture viewer.
Software: [click here]
Install and use the utility program to test your servo's. The utility program does not control the OE pin, so you'll need to set it low manually.