PIC17C752 MICROCHIP [Microchip Technology], PIC17C752 Datasheet - Page 164

• Manufacturer Part Number: PIC17C752
• Description: High-Performance 8-Bit CMOS EPROM Microcontrollers
• Manufacturer: MICROCHIP [Microchip Technology]

15.2.14.3 BUS COLLISION DURING A STOP
Bus collision occurs during a STOP condition if:
a)
b)
FIGURE 15-43: BUS COLLISION DURING A STOP CONDITION (CASE 1)
FIGURE 15-44: BUS COLLISION DURING A STOP CONDITION (CASE 2)
DS30264A-page 164
After the SDA pin has been de-asserted and
allowed to float high, SDA is sampled low after
the BRG has timed out.
After the SCL pin is de-asserted, SCL is sam-
pled low before SDA goes high.
SDA
SCL
PEN
BCLIF
P
SSPIF
SSPIF
BCLIF
SDA
PEN
CONDITION
SCL
P
Assert SDA
T
SDA asserted low
BRG
T
BRG
Preliminary
T
BRG
T
BRG
The STOP condition begins with SDA asserted low.
When SDA is sampled low, the SCL pin is allow to
float. When the pin is sampled high (clock arbitration),
the baud rate generator is loaded with SSPADD<6:0>
and counts down to 0. After the BRG times out SDA is
sampled. If SDA is sampled low, a bus collision has
occurred. This is due to another master attempting to
drive a data '0'. If the SCL pin is sampled low before
SDA is allowed to float high, a bus collision occurs.
This is another case of another master attempting to
drive a data '0'. (Figure 15-43)
SCL goes low before SDA goes high
Set BCLIF
T
BRG
T
BRG
1997 Microchip Technology Inc.
SDA sampled
low after T
Set BCLIF
BRG
,