PIC12F1516 MICROCHIP [Microchip Technology], PIC12F1516 Datasheet - Page 228

• Manufacturer Part Number: PIC12F1516
• Description: 28/40/44-Pin Flash Microcontrollers with nanoWatt XLP Technology
• Manufacturer: MICROCHIP [Microchip Technology]

PIC16(L)F1516/7/8/9
21.6.13.2
During a Repeated Start condition, a bus collision
occurs if:
a)
b)
When the user releases SDA and the pin is allowed to
float high, the BRG is loaded with SSPADD and counts
down to zero. The SCL pin is then deasserted and
when sampled high, the SDA pin is sampled.
FIGURE 21-36:
FIGURE 21-37:
DS41452B-page 228
A low level is sampled on SDA when SCL goes
from low level to high level.
SCL goes low before SDA is asserted low,
indicating that another master is attempting to
transmit a data ‘1’.
SDA
SCL
BCLIF
RSEN
S
SSPIF
SDA
SCL
RSEN
BCLIF
S
SSPIF
Bus Collision During a Repeated
Start Condition
BUS COLLISION DURING A REPEATED START CONDITION (CASE 1)
BUS COLLISION DURING REPEATED START CONDITION (CASE 2)
SCL goes low before SDA,
set BCLIF. Release SDA and SCL.
Preliminary
T
BRG
Sample SDA when SCL goes high.
If SDA = 0, set BCLIF and release SDA and SCL.
If SDA is low, a bus collision has occurred (i.e., another
master is attempting to transmit a data ‘0’,
If SDA is sampled high, the BRG is reloaded and begins
counting. If SDA goes from high-to-low before the BRG
times out, no bus collision occurs because no two
masters can assert SDA at exactly the same time.
If SCL goes from high-to-low before the BRG times out
and SDA has not already been asserted, a bus collision
occurs. In this case, another master is attempting to
transmit a data ‘1’ during the Repeated Start condition,
see
If, at the end of the BRG time-out, both SCL and SDA
are still high, the SDA pin is driven low and the BRG is
reloaded and begins counting. At the end of the count,
regardless of the status of the SCL pin, the SCL pin is
driven low and the Repeated Start condition is
complete.
Figure
21-36.
T
Cleared by software
 2011 Microchip Technology Inc.
BRG
Interrupt cleared
by software
’0’
’0’
’0’
Figure
21-35).