This shield is a relatively simple breakout board for the PCA9685 chip. Apart from that chip, it only contains the bare minimum of components necessary to make it work, and all the necessary connections. The goal is to make it as convenient as possible to connect hobby servos to the ESP8266.
The board has the standard size and shape of D1 Mini shields, with the servo sockets broken out as angled headers, protruding on the sides, so that the boards can be easily stacked with each other or with other shields. Up to 64 such shields can be used with a single microcontroller, provided that they have different addresses set.
The chip takes care of continuously generating the signal that is expected by the hobby servos, freeing the microcontroller from this task. The microcontroller only needs to get involved when you want to change the position of any of the servos – it sends a command then, and from that moment the shield will generate the signal for the new position for that servo.
This shield is 100% compatible with other servo controllers using PCA9685 chip, and can be used as a drop-in replacement for them. All the available libraries and examples should work exactly the same.