PIC18F248-E/L MICROCHIP [Microchip Technology], PIC18F248-E/L Datasheet - Page 183

• Manufacturer Part Number: PIC18F248-E/L
• Description: 28/40-Pin High-Performance, Enhanced Flash Microcontrollers with CAN Module
• Manufacturer: MICROCHIP [Microchip Technology]

17.4.17.3
Bus collision occurs during a Stop condition if:
a)
b)
FIGURE 17-31:
FIGURE 17-32:
© 2006 Microchip Technology Inc.
After the SDA pin has been deasserted and
allowed to float high, SDA is sampled low after
the BRG has timed out.
After the SCL pin is deasserted, SCL is sampled
low before SDA goes high.
SDA
SCL
PEN
BCLIF
P
SSPIF
SSPIF
BCLIF
SDA
PEN
SCL
Bus Collision During a Stop
Condition
P
BUS COLLISION DURING A STOP CONDITION (CASE 1)
BUS COLLISION DURING A STOP CONDITION (CASE 2)
Assert SDA
T
SDA asserted low
BRG
T
BRG
T
BRG
T
BRG
The Stop condition begins with SDA asserted low.
When SDA is sampled low, the SCL pin is allowed 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’ (Figure 17-31). 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 17-32).
SCL goes low before SDA goes high,
set BCLIF
T
BRG
T
BRG
PIC18FXX8
‘0’
‘0’
DS41159E-page 181
SDA sampled
low after T
set BCLIF
‘0’
‘0’
BRG
,