PIC17C7XX Datasheet, PDF (163/328 Pages) Microchip Technology – High-Performance 8-Bit CMOS EPROM Microcontrollers with 10-bit A/D

15.2.13 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. 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)
PIC17C7XX
15.2.13.1 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 WAVEFORM
Acknowledge sequence starts here,
Write to SSPCON2
ACKEN = 1, ACKDT = 0
SDA
T_BRG
T_BRG
D0
ACK
SCL
8
9
ACKEN automatically cleared
SSPIF
Set SSPIF at the end
of receive
Cleared in
software
Note: T_BRG= one baud rate generator period.
Cleared in
software
Set SSPIF at the end
of acknowledge sequence
© 1998 Microchip Technology Inc.
DS30289A-page 163