26.5.1 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
By default, there are 4 clock cycles of setup time on SDA out signal while reading from slave part of the TWI module. Writing this bit to '1' will change the setup time to 8 clocks.
| Value | Name | Description |
|---|---|---|
| 0 | 4CYC | SDA setup time is 4 clock cycles |
| 1 | 8CYC | SDA setup time is 8 clock cycle |
Bits 3:2 – SDAHOLD[1:0] SDA Hold Time
Writing these bits selects the SDA hold time.
| SDAHOLD[1:0] | Nominal Hold Time | Hold Time Range across All Corners (ns) | Description |
|---|---|---|---|
| 0x0 | OFF | 0 | Hold time off. |
| 0x1 | 50ns | 36 - 131 | Backward compatible setting. |
| 0x2 | 300ns | 180 - 630 | Meets SMBus specification under typical conditions. |
| 0x3 | 500ns | 300 - 1050 | Meets SMBus specification across all corners. |
Bit 1 – FMPEN FM Plus Enable
Writing these bits selects the 1MHz bus speed (Fast mode plus, Fm+) for the TWI in default configuration.
| Value | Description |
|---|---|
| 0 | Fm+ disabled |
| 1 | Fm+ enabled |