at94k40al ATMEL Corporation, at94k40al Datasheet - Page 148

• Manufacturer Part Number: at94k40al
• Description: At94kal Series Field Programmable System Level Integrated Circuit
• Manufacturer: ATMEL Corporation

4.30.1.5
Miscellaneous States
There are two status codes that do not correspond to a defined 2-wire Serial Interface state: Sta-
tus $F8 and Status $00, see
Table
4-33.
Status $F8 indicates that no relevant information is available because the 2-wire Serial Interrupt
flag (TWINT) is not set yet. This occurs between other states, and when the 2-wire Serial Inter-
face is not involved in a serial transfer.
Status $00 indicates that a bus error has occurred during a 2-wire serial transfer. A bus error
occurs when a START or STOP condition occurs at an illegal position in the format frame.
Examples of such illegal positions are during the serial transfer of an address byte, a data byte
or an acknowledge bit. When a bus error occurs, TWINT is set. To recover from a bus error, the
TWSTO flag must set and TWINT must be cleared by writing a logic 1 to it. This causes the 2-
wire Serial Interface to enter the not addressed Slave mode and to clear the TWSTO flag (no
other bits in TWCR are affected). The SDA and SCL lines are released and no STOP condition
is transmitted.
AT94KAL Series FPSLIC
148
1138I–FPSLI–1/08