I bought an Adafruit Servo Hat - it works totally differently to the Pimoroni Pantilt hat!
This is my Go port of the Adafruit pca9685 library for the Adafruit panTilt hat on a RasPi
Didn't get on with the experimental pca9685 device package under periph... so looked at other libraries. please refer to this:-
https://learn.adafruit.com/adafruit-16-channel-pwm-servo-hat-for-raspberry-pi/library-reference
Note that the values of servo Max and Min are different to those in periph. Also the experimental code in periph needs a stop/halt function!
NBBB I haven't gone into the depths of PWM - The first attempts managed to turn my little servos into 360degree rotators (there was a sound of the end stop being destroyed in at least one of them) Amazingly they still work now that the software is under control.
Now where were those Ping-Pong balls to make the eyes .... RichR