APB2 peripheral clock enable register (CRM_APB2EN)
| SCFGCMPEN | Syscfg and comparator clock enable |
| ADCEN | ADC clock enable |
| TMR1EN | Timer1 clock enable |
| SPI1EN | SPI1 clock enable |
| USART1EN | USART1 clock enable |
| TMR15EN | Timer15 clock enable |
| TMR16EN | Timer16 clock enable |
| TMR17EN | Timer17 clock enable |