25.5.1 Control A
| Name: | CTRLA |
| Offset: | 0x00 |
| Reset: | 0x00 |
| Property: | - |
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| SDASETUP | SDAHOLD[1:0] | FMPEN | |||||||
| Access | R/W | R/W | R/W | R/W | |||||
| Reset | 0 | 0 | 0 | 0 | |||||
Bit 4 – SDASETUP SDA Setup Time
This bit is used in TWI Client mode to select the clock hold time to ensure minimum setup time on the SDA out signal.
By default, there are four clock cycles of setup time on the SDA out signal while
reading from the client part of the TWI module. Writing this bit to
‘1’ will change the setup time to eight clock cycles.
| Value | Name | Description |
|---|---|---|
| 0 | 4CYC | SDA setup time is four clock cycles |
| 1 | 8CYC | SDA setup time is eight clock cycles |
Bits 3:2 – SDAHOLD[1:0] SDA Hold Time
Writing this bit field selects the SDA hold time for the TWI. See the Electrical Characteristics section for details.
| Value | Name | Description |
|---|---|---|
| 0x0 | OFF | Hold time OFF |
| 0x1 | 50NS | Short hold time |
| 0x2 | 300NS | Meets the SMBus 2.0 specifications under typical conditions |
| 0x3 | 500NS | Meets the SMBus 2.0 specifications across all corners |
Bit 1 – FMPEN FM Plus Enable
Writing a ‘1’ to this bit selects the 1 MHz bus speed (Fast mode
plus, Fm+) for the TWI in default configuration or TWI Host in Dual mode
configuration.
| Value | Description |
|---|---|
| 0 | Operating in Standard mode or Fast mode |
| 1 | Operating in Fast mode plus |