APB1 peripheral clock enable register
| TIM2EN | TIM2 clock enable | 
| TIM3EN | TIM3 clock enable | 
| TIM4EN | TIM4 clock enable | 
| TIM5EN | TIM5 clock enable | 
| TIM6EN | TIM6 clock enable | 
| TIM7EN | TIM7 clock enable | 
| TIM12EN | TIM12 clock enable | 
| TIM13EN | TIM13 clock enable | 
| TIM14EN | TIM14 clock enable | 
| LPTMI1EN | Low power timer 1 clock enable | 
| WWDGEN | Window watchdog clock enable | 
| SPI2EN | SPI2 clock enable | 
| SPI3EN | SPI3 clock enable | 
| SPDIFRXEN | SPDIF-RX clock enable | 
| USART2EN | USART 2 clock enable | 
| USART3EN | USART3 clock enable | 
| UART4EN | UART4 clock enable | 
| UART5EN | UART5 clock enable | 
| I2C1EN | I2C1 clock enable | 
| I2C2EN | I2C2 clock enable | 
| I2C3EN | I2C3 clock enable | 
| I2C4EN | I2C4 clock enable | 
| CAN1EN | CAN 1 clock enable | 
| CAN2EN | CAN 2 clock enable | 
| CECEN | HDMI-CEN clock enable | 
| PWREN | Power interface clock enable | 
| DACEN | DAC interface clock enable | 
| UART7ENR | UART7 clock enable | 
| UART8ENR | UART8 clock enable |