Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Keil/AT32F415xx_v2/ERTC/SCAL#0x0
calibration register
Decrease ERTC clock
16 second calibration period
8-second calibration period
Add ERTC clock
https://github.com/cmsis-svd/cmsis-svd-data