PIC16F872
FIGURE 9-21: BUS COLLISION DURING START CONDITION (SCL = 0)
SDA = 0, SCL = 1
TBRG
TBRG
SDA
SCL
SEN
Set SEN, enable start
sequence if SDA = 1, SCL = 1
SCL = 0 before SDA = 0,
Bus collision occurs, Set BCLIF
SCL = 0 before BRG time out,
Bus collision occurs, Set BCLIF
BCLIF
Interrupts cleared
in software
S
’0’
’0’
’0’
’0’
SSPIF
FIGURE 9-22: BRG RESET DUE TO SDA COLLISION DURING START CONDITION
SDA = 0, SCL = 1
Set S
Set SSPIF
Less than TBRG
TBRG
SDA pulled low by other master
Reset BRG and assert SDA
SDA
SCL
s
SCL pulled low after BRG
Timeout
SEN
Set SEN, enable start
sequence if SDA = 1, SCL = 1
’0’
BCLIF
S
SSPIF
Interrupts cleared
in software
SDA = 0, SCL = 1
Set SSPIF
DS30221A-page 80
Preliminary
1999 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
