RCC Domain 2 Kernel Clock Configuration Register
| USART234578SEL | USART2/3, UART4,5, 7/8 (APB1) kernel clock source selection |
| USART16910SEL | USART1 and 6 kernel clock source selection |
| RNGSEL | RNG kernel clock source selection |
| I2C123SEL | I2C1,2,3 kernel clock source selection |
| USBSEL | USBOTG 1 and 2 kernel clock source selection |
| CECSEL | HDMI-CEC kernel clock source selection |
| LPTIM1SEL | LPTIM1 kernel clock source selection |