29.5.11 Client Control B
| Name: | SCTRLB |
| Offset: | 0x0A |
| Reset: | 0x00 |
| Property: | - |
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| ACKACT | SCMD[1:0] | ||||||||
| Access | R/W | R/W | R/W | ||||||
| Reset | 0 | 0 | 0 | ||||||
Bit 2 – ACKACT Acknowledge Action
The ACKACT(1) bit represents the behavior of
the TWI client under certain conditions defined by the bus protocol state and
the software interaction. If the Smart Mode Enable (SMEN) bit in the Client
Control A (TWIn.SCTRLA) register is set to ‘1’, the acknowledge
action is performed when the Client Data (TWIn.SDATA) register is read.
Otherwise a command must be written to the Command (SCMD) bit field in the
Client Control B (TWIn.SCTRLB) register.
The acknowledge action is not performed when the Client Data (TWIn.SDATA) register is written since the client is sending data.
| Value | Name | Description |
|---|---|---|
| 0 | ACK | Send ACK |
| 1 | NACK | Send NACK |
Bits 1:0 – SCMD[1:0] Command
The SCMD(1) bit field is a strobe. This bit field
is always read as ‘0’.
Writing to this bit field triggers a client operation as defined by the table below.
| Value | Name | DIR | Description | |
|---|---|---|---|---|
0x0 |
NOACT | X | No action | |
0x1 |
— | X | Reserved | |
0x2 |
COMPTRANS | W | Execute Acknowledge Action succeeded by waiting for any Start (S/Sr) condition | Used to complete a transaction |
| R | Wait for any Start (S/Sr) condition | |||
0x3 |
RESPONSE | W | Execute Acknowledge Action succeeded by the reception of the next byte | |
| R | Used in response to an address interrupt (APIF): Execute Acknowledge Action succeeded by client data interrupt. | |||
| Used in response to a data interrupt (DIF): Execute a byte read operation followed by Acknowledge Action. | ||||