18.4.2 SMB0TC: SMBus 0 Timing and Pin Control
Bit
7
6
5
4
3
2
1
0
Name
SWAP
Reserved
DLYEXT
Reserved
SDD
Access
RW
R
RW
R
RW
Reset
0
0x0
0
0x0
0x0
SFR Page = 0x0, 0x20; SFR Address: 0xAC
Bit
Name
Reset
Access Description
7
SWAP
0
RW
SMBus Swap Pins.
This bit swaps the order of the SMBus pins on the crossbar.
Value
Name
Description
0
SDA_LOW_PIN
SDA is mapped to the lower-numbered port pin, and SCL is mapped to
the higher-numbered port pin.
1
SDA_HIGH_PIN
SCL is mapped to the lower-numbered port pin, and SDA is mapped to
the higher-numbered port pin.
6:5
Reserved
Must write reset value.
4
DLYEXT
0
RW
Setup and Hold Delay Extension Selection.
This bit is only active if EXTHOLD is 1.
Value
Name
Description
0
SHORT
SDA Setup time is 11 SYSCLKs. SDA Hold time is 12 SYSCLKs.
1
LONG
SDA Setup and Hold time is 31 SYSCLKs.
3:2
Reserved
Must write reset value.
1:0
SDD
0x0
RW
SMBus Start Detection Window.
This field is used to delay the recognition of the falling edge of the SDA signal. This feature should be applied in cases
where a data bit transition occurs close to the SCL falling edge that may cause a false START detection when there is a
significant mismatch between the impedance or capacitance on the SDA and SCL lines. This field should be left in the de-
fault setting in most cases.
Value
Name
Description
0x0
NONE
No additional SDA falling edge recognition delay (0-1 SYSCLK).
0x1
ADD_2_SYSCLKS
Increase SDA falling edge recognition time window to 2-3 SYSCLKs af-
ter the SCL falling edge.
0x2
ADD_4_SYSCLKS
Increase SDA falling edge recognition window to 4-5 SYSCLKs after
the SCL falling edge.
0x3
ADD_8_SYSCLKS
Increase SDA falling edge recognition window to 8-9 SYSCLKs after
the SCL falling edge.
EFM8UB3 Reference Manual
System Management Bus / I2C (SMB0)
silabs.com
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