AHB peripheral clock enable register
| GPIOPAEN | IO port A clock enable |
| GPIOPBEN | IO port B clock enable |
| GPIOPCEN | IO port C clock enable |
| GPIOPDEN | IO port D clock enable |
| GPIOPEEN | IO port E clock enable |
| GPIOPHEN | IO port H clock enable |
| GPIOPFEN | IO port F clock enable |
| GPIOPGEN | IO port G clock enable |
| CRCEN | CRC clock enable |
| FLITFEN | FLITF clock enable |
| DMA1EN | DMA1 clock enable |
| DMA2EN | DMA2 clock enable |
| FSMCEN | FSMCEN |