Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Fujitsu/MB9BF41xS/BTIOSEL47/BTSEL4567#0x0
I/O Select Register
I/O select bits for Ch.4/Ch.5
I/O select bits for Ch.6/Ch.7
https://github.com/cmsis-svd/cmsis-svd-data