PIC18F8722-I/PT Microchip Technology Inc., PIC18F8722-I/PT Datasheet - Page 245

• Manufacturer Part Number: PIC18F8722-I/PT
• Description: 80 PIN, 128 KB FLASH, 4K RAM, 70 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F8722-I/PT

• A/d Inputs: 16-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 10 MIPS
• Eeprom Memory: 1024 Bytes
• Input Output: 70
• Interface: SPI/I2C/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 80-pin TQFP
• Programmable Memory: 128K Bytes
• Ram Size: 3.9K Bytes
• Speed: 40 MHz
• Timers: 2-8 bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

19.4.17.2
During a Repeated Start condition, a bus collision
occurs if:
a)
b)
When the user deasserts SDAx and the pin is allowed
to float high, the BRG is loaded with SSPxADD<6:0>
and counts down to ‘0’. The SCLx pin is then
deasserted and when sampled high, the SDAx pin is
sampled.
FIGURE 19-29:
FIGURE 19-30:
 2004 Microchip Technology Inc.
A low level is sampled on SDAx when SCLx
goes from low level to high level.
SCLx goes low before SDAx is asserted low,
indicating that another master is attempting to
transmit a data ‘1’.
SDAx
SCLx
BCLxIF
RSEN
S
SSPxIF
SDAx
SCLx
RSEN
BCLxIF
S
SSPxIF
Bus Collision During a Repeated
Start Condition
BUS COLLISION DURING A REPEATED START CONDITION (CASE 1)
BUS COLLISION DURING REPEATED START CONDITION (CASE 2)
SCLx goes low before SDAx,
set BCLxIF. Release SDAx and SCLx.
Preliminary
T
BRG
Sample SDAx when SCLx goes high.
If SDAx = 0, set BCLxIF and release SDAx and SCLx.
If SDAx is low, a bus collision has occurred (i.e., another
master is attempting to transmit a data ‘0’, Figure 19-29).
If SDAx is sampled high, the BRG is reloaded and
begins counting. If SDAx goes from high-to-low before
the BRG times out, no bus collision occurs because no
two masters can assert SDAx at exactly the same time.
If SCLx goes from high-to-low before the BRG times
out and SDAx 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 Figure 19-30).
If, at the end of the BRG time-out, both SCLx and SDAx
are still high, the SDAx pin is driven low and the BRG is
reloaded and begins counting. At the end of the count,
regardless of the status of the SCLx pin, the SCLx pin is
driven low and the Repeated Start condition is complete.
PIC18F8722 FAMILY
Cleared in software
T
BRG
Interrupt cleared
in software
‘0’
‘0’
DS39646B-page 243
‘0’