PIC18F24 MICROCHIP [Microchip Technology], PIC18F24 Datasheet - Page 178

• Manufacturer Part Number: PIC18F24
• Description: 28/40-Pin High-Performance, Enhanced Flash Microcontrollers with CAN Module
• Manufacturer: MICROCHIP [Microchip Technology]

17.4.12
An Acknowledge sequence is enabled by setting the
Acknowledge
(SSPCON2<4>). When this bit is set, the SCL pin is
pulled low and the contents of the Acknowledge data bit
are presented on the SDA pin. If the user wishes to gen-
erate an Acknowledge, then the ACKDT bit should be
cleared. If not, the user should set the ACKDT bit before
starting an Acknowledge sequence. The Baud Rate
Generator then counts for one rollover period (T
and the SCL pin is deasserted (pulled high). When the
SCL pin is sampled high (clock arbitration), the Baud
Rate Generator counts for T
pulled low. Following this, the ACKEN bit is automatically
cleared, the Baud Rate Generator is turned off and the
MSSP module then goes into Idle mode (Figure 17-23).
17.4.12.1
If the user writes the SSPBUF when an Acknowledge
sequence is in progress, then WCOL is set and the con-
tents of the buffer are unchanged (the write doesn’t occur).
FIGURE 17-23:
FIGURE 17-24:
DS41159D-page 176
PIC18FXX8
Note: T
Note: T
ACKNOWLEDGE SEQUENCE
TIMING
SCL
SDA
WCOL Status Flag
Sequence
Falling edge of
9th clock
SSPIF
BRG
BRG
Write to SSPCON2
Acknowledge sequence starts here,
SDA
SCL
= one Baud Rate Generator period.
= one Baud Rate Generator period.
ACKNOWLEDGE SEQUENCE WAVEFORM
STOP CONDITION RECEIVE OR TRANSMIT MODE
ACK
Set SSPIF at the end
of receive
Set PEN
BRG
ACKEN = 1, ACKDT = 0
Enable
. The SCL pin is then
write to SSPCON2
T
T
BRG
BRG
SDA asserted low before rising edge of clock
to setup Stop condition
bit,
8
D0
ACKEN
T
SCL brought high after T
BRG
BRG
)
Cleared in
software
P
T
SCL = 1 for T
after SDA sampled high. P bit (SSPSTAT<4>) is set.
BRG
T
BRG
ACK
17.4.13
A Stop bit is asserted on the SDA pin at the end of a
receive/transmit by setting the Stop Sequence Enable
bit, PEN (SSPCON2<2>). At the end of a receive/
transmit, the SCL line is held low after the falling edge
of the ninth clock. When the PEN bit is set, the master
will assert the SDA line low. When the SDA line is
sampled low, the Baud Rate Generator is reloaded and
counts down to 0. When the Baud Rate Generator
times out, the SCL pin will be brought high and one
T
SDA pin will be deasserted. When the SDA pin is
sampled high while SCL is high, the P bit
(SSPSTAT<4>) is set. A T
cleared and the SSPIF bit is set (Figure 17-24).
17.4.13.1
If the user writes the SSPBUF when a Stop sequence
is in progress, then the WCOL bit is set and the con-
tents of the buffer are unchanged (the write doesn’t
occur).
BRG
PEN bit (SSPCON2<2>) is cleared by
T
hardware and the SSPIF bit is set
BRG
9
BRG
BRG
(Baud Rate Generator rollover count) later, the
Set SSPIF at the end
of Acknowledge sequence
, followed by SDA = 1 for T
STOP CONDITION TIMING
WCOL Status Flag
ACKEN automatically cleared
 2004 Microchip Technology Inc.
Cleared in
software
BRG
BRG
later, the PEN bit is