PECBYTE=B_0x0, STOP=B_0x0, START=B_0x0, ADD10=B_0x0, RD_WRN=B_0x0, HEAD10R=B_0x0, AUTOEND=B_0x0, RELOAD=B_0x0, NACK=B_0x0
Control register 2
| SADD | Slave address (master mode) In 7-bit addressing mode (ADD10 = 0): SADD[7:1] should be written with the 7-bit slave address to be sent. The bits SADD[9], SADD[8] and SADD[0] are don’t care. In 10-bit addressing mode (ADD10 = 1): SADD[9:0] should be written with the 10-bit slave address to be sent. Note: Changing these bits when the START bit is set is not allowed. |
| RD_WRN | Transfer direction (master mode) Note: Changing this bit when the START bit is set is not allowed. 0 (B_0x0): Master requests a write transfer. 1 (B_0x1): Master requests a read transfer. |
| ADD10 | 10-bit addressing mode (master mode) Note: Changing this bit when the START bit is set is not allowed. 0 (B_0x0): The master operates in 7-bit addressing mode, 1 (B_0x1): The master operates in 10-bit addressing mode |
| HEAD10R | 10-bit address header only read direction (master receiver mode) Note: Changing this bit when the START bit is set is not allowed. 0 (B_0x0): The master sends the complete 10 bit slave address read sequence: Start + 2 bytes 10bit address in write direction + Restart + 1st 7 bits of the 10 bit address in read direction. 1 (B_0x1): The master only sends the 1st 7 bits of the 10 bit address, followed by Read direction. |
| START | Start generation This bit is set by software, and cleared by hardware after the Start followed by the address sequence is sent, by an arbitration loss, by a timeout error detection, or when PE = 0. It can also be cleared by software by writing '1â to the ADDRCF bit in the I2C_ICR register. If the I2C is already in master mode with AUTOEND = 0, setting this bit generates a Repeated Start condition when RELOAD=0, after the end of the NBYTES transfer. Otherwise setting this bit generates a START condition once the bus is free. Note: Writing '0â to this bit has no effect. The START bit can be set even if the bus is BUSY or I2C is in slave mode. This bit has no effect when RELOAD is set. 0 (B_0x0): No Start generation. 1 (B_0x1): Restart/Start generation: |
| STOP | Stop generation (master mode) The bit is set by software, cleared by hardware when a STOP condition is detected, or when PE = 0. In Master Mode: Note: Writing '0â to this bit has no effect. 0 (B_0x0): No Stop generation. 1 (B_0x1): Stop generation after current byte transfer. |
| NACK | NACK generation (slave mode) The bit is set by software, cleared by hardware when the NACK is sent, or when a STOP condition or an Address matched is received, or when PE=0. Note: Writing '0â to this bit has no effect. This bit is used in slave mode only: in master receiver mode, NACK is automatically generated after last byte preceding STOP or RESTART condition, whatever the NACK bit value. When an overrun occurs in slave receiver NOSTRETCH mode, a NACK is automatically generated whatever the NACK bit value. When hardware PEC checking is enabled (PECBYTE=1), the PEC acknowledge value does not depend on the NACK value. 0 (B_0x0): an ACK is sent after current received byte. 1 (B_0x1): a NACK is sent after current received byte. |
| NBYTES | Number of bytes The number of bytes to be transmitted/received is programmed there. This field is donât care in slave mode with SBC=0. Note: Changing these bits when the START bit is set is not allowed. |
| RELOAD | NBYTES reload mode This bit is set and cleared by software. 0 (B_0x0): The transfer is completed after the NBYTES data transfer (STOP or RESTART follows). 1 (B_0x1): The transfer is not completed after the NBYTES data transfer (NBYTES is reloaded). TCR flag is set when NBYTES data are transferred, stretching SCL low. |
| AUTOEND | Automatic end mode (master mode) This bit is set and cleared by software. Note: This bit has no effect in slave mode or when the RELOAD bit is set. 0 (B_0x0): software end mode: TC flag is set when NBYTES data are transferred, stretching SCL low. 1 (B_0x1): Automatic end mode: a STOP condition is automatically sent when NBYTES data are transferred. |
| PECBYTE | Packet error checking byte This bit is set by software, and cleared by hardware when the PEC is transferred, or when a STOP condition or an Address matched is received, also when PE=0. Note: Writing '0â to this bit has no effect. This bit has no effect when RELOAD is set. This bit has no effect is slave mode when SBC=0. If the SMBus feature is not supported, this bit is reserved and forced by hardware to '0â. Refer to . 0 (B_0x0): No PEC transfer. 1 (B_0x1): PEC transmission/reception is requested |