PIC17C75X Datasheet, PDF (155/320 Pages) Microchip Technology – High-Performance 8-Bit CMOS EPROM Microcontrollers

15.2.11 ACKNOWLEDGE SEQUENCE TIMING
An acknowledge sequence is enabled by setting the
acknowledge sequence enable bit, ACKEN
(SSPCON2<4>). When this bit is set, the SCL pin is
pulled low and the contents of the acknowledge data
bit is presented on the SDA pin. If the user wishes to
generate 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_BRG), and the SCL pin is de-asserted (pulled high).
When the SCL pin is sampled high (clock arbitration),
the baud rate generator counts for T_BRG . The SCL
pin is then pulled low for one T_BRG. Following this,
the ACKEN bit is automatically cleared, the baud rate
generator is turned off, and the SSP module then goes
into IDLE mode. (Figure 15-32)
PIC17C75X
15.2.11.1 WCOL STATUS FLAG
If the user writes the SSPBUF when an acknowledege
sequence is in progress, then WCOL is set and the
contents of the buffer are unchanged (the write doesn’t
occur).
FIGURE 15-32: ACKNOWLEDGE SEQUENCE TIMING
Acknowledge sequence starts here
Write to SSPCON2
ACKEN = 1, ACKDT = 0
SDA
D0
SCL
8
T_BRG
T_BRG
ACK
9
ACKEN automatically cleared
SSPIF
Set SSPIF at the end
of receive
Note: T_BRG= one baud rate generator period.
Cleared in
software
Cleared in
software
Set SSPIF at the end
of acknowledge sequence
© 1997 Microchip Technology Inc.
Preliminary
DS30264A-page 155