If SHUTDOWN (WAKE pin) feature is not needed, the pin can be leave unconnected

[rtek1000]

From GSL1680 datasheet:

SHUTDOWN pin is recommended to connect to the GPIO of host. If pull the SHUTDOWN pin low
by the host, the GSL168X will enter the deepsleep state to consume the least power. To wake up
GSL168X from deepsleep, host has to release SHUTDOWN to high and send a START_COMMAND to
GSL168X to kick it off. If SHUTDOWN feature is not needed, the pin can be leave unconnected.

I tested it and I didn't need to use the pin. But the code does not allow booting without the WAKE pin, so I made modifications to adapt the original code.

[rtek1000]

GSL1680.pdf