APB peripheral clock enable register 1
| TIM2EN | TIM2 timer clock enable |
| TIM3EN | TIM3 timer clock enable |
| RTCAPBEN | RTC APB clock enable |
| WWDGEN | WWDG clock enable |
| SPI2EN | SPI2 clock enable |
| USART2EN | USART2 clock enable |
| LPUART1EN | LPUART1 clock enable |
| I2C1EN | I2C1 clock enable |
| I2C2EN | I2C2 clock enable |
| DBGEN | Debug support clock enable |
| PWREN | Power interface clock enable |
| LPTIM2EN | LPTIM2 clock enable |
| LPTIM1EN | LPTIM1 clock enable |