Control register 1
| PE | Peripheral enable |
| TXIE | TX Interrupt enable |
| RXIE | RX Interrupt enable |
| ADDRIE | Address match interrupt enable (slave only) |
| NACKIE | Not acknowledge received interrupt enable |
| STOPIE | STOP detection Interrupt enable |
| TCIE | Transfer Complete interrupt enable |
| ERRIE | Error interrupts enable |
| DNF | Digital noise filter |
| ANFOFF | Analog noise filter OFF |
| TXDMAEN | DMA transmission requests enable |
| RXDMAEN | DMA reception requests enable |
| SBC | Slave byte control |
| NOSTRETCH | Clock stretching disable |
| WUPEN | Wakeup from STOP enable |
| GCEN | General call enable |
| SMBHEN | SMBus Host address enable |
| SMBDEN | SMBus Device Default address enable |
| ALERTEN | SMBUS alert enable |
| PECEN | PEC enable |
| FMP | Fast-mode Plus 20 mA drive enable |
| ADDRACLR | Address match flag (ADDR) automatic clear |
| STOPFACLR | STOP detection flag (STOPF) automatic clear |