clock configuration register
| SW0 | System clock switch |
| SW1 | System clock switch |
| SWS0 | System clock switch status |
| SWS1 | System clock switch status |
| HPRE0 | AHB prescaler |
| HPRE1 | AHB prescaler |
| HPRE2 | AHB prescaler |
| HPRE3 | AHB prescaler |
| PPRE10 | APB Low speed prescaler (APB1) |
| PPRE11 | APB Low speed prescaler (APB1) |
| PPRE12 | APB Low speed prescaler (APB1) |
| PPRE20 | APB high-speed prescaler (APB2) |
| PPRE21 | APB high-speed prescaler (APB2) |
| PPRE22 | APB high-speed prescaler (APB2) |
| RTCPRE0 | HSE division factor for RTC clock |
| RTCPRE1 | HSE division factor for RTC clock |
| RTCPRE2 | HSE division factor for RTC clock |
| RTCPRE3 | HSE division factor for RTC clock |
| RTCPRE4 | HSE division factor for RTC clock |
| MCO10 | Microcontroller clock output 1 |
| MCO11 | Microcontroller clock output 1 |
| I2SSRC | I2S clock selection |
| MCO1PRE0 | MCO1 prescaler |
| MCO1PRE1 | MCO1 prescaler |
| MCO1PRE2 | MCO1 prescaler |
| MCO2PRE0 | MCO2 prescaler |
| MCO2PRE1 | MCO2 prescaler |
| MCO2PRE2 | MCO2 prescaler |
| MCO20 | Microcontroller clock output 2 |
| MCO21 | Microcontroller clock output 2 |