C8051F124-GQR Datasheet, PDF (266/350 Pages) Silicon Laboratories – Mixed Signal ISP Flash MCU Family

C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 19.1. SMB0CN: SMBus0 Control
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W Reset Value
BUSY ENSMB STA
STO
SI
AA
FTE
TOE 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0xC0
SFR Page: 0
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
BUSY: Busy Status Flag.
0: SMBus0 is free
1: SMBus0 is busy
ENSMB: SMBus Enable.
This bit enables/disables the SMBus serial interface.
0: SMBus0 disabled.
1: SMBus0 enabled.
STA: SMBus Start Flag.
0: No START condition is transmitted.
1: When operating as a master, a START condition is transmitted if the bus is free. (If the
bus is not free, the START is transmitted after a STOP is received.) If STA is set after one or
more bytes have been transmitted or received and before a STOP is received, a repeated
START condition is transmitted.
STO: SMBus Stop Flag.
0: No STOP condition is transmitted.
1: Setting STO to logic 1 causes a STOP condition to be transmitted. When a STOP condi-
tion is received, hardware clears STO to logic 0. If both STA and STO are set, a STOP con-
dition is transmitted followed by a START condition. In slave mode, setting the STO flag
causes SMBus to behave as if a STOP condition was received.
SI: SMBus Serial Interrupt Flag.
This bit is set by hardware when one of 27 possible SMBus0 states is entered. (Status code
0xF8 does not cause SI to be set.) When the SI interrupt is enabled, setting this bit causes
the CPU to vector to the SMBus interrupt service routine. This bit is not automatically
cleared by hardware and must be cleared by software.
AA: SMBus Assert Acknowledge Flag.
This bit defines the type of acknowledge returned during the acknowledge cycle on the SCL
line.
0: A "not acknowledge" (high level on SDA) is returned during the acknowledge cycle.
1: An "acknowledge" (low level on SDA) is returned during the acknowledge cycle.
FTE: SMBus Free Timer Enable Bit
0: No timeout when SCL is high
1: Timeout when SCL high time exceeds limit specified by the SMB0CR value.
TOE: SMBus Timeout Enable Bit
0: No timeout when SCL is low.
1: Timeout when SCL low time exceeds limit specified by Timer 3, if enabled.
266
Rev. 1.4