APB2 peripheral clock enable register (RCC_APB2ENR)
| SYSCFGEN | SYSCFG clock enable |
| ADCEN | ADC 1 interface clock enable |
| TIM1EN | TIM1 Timer clock enable |
| SPI1EN | SPI 1 clock enable |
| USART1EN | USART1 clock enable |
| TIM16EN | TIM16 timer clock enable |
| TIM17EN | TIM17 timer clock enable |
| DBGMCUEN | MCU debug module clock enable |