Datasheet

PIC18F2420/2520/4420/4520
DS39631E-page 182 © 2008 Microchip Technology Inc.
FIGURE 17-13: I
2
C™ SLAVE MODE TIMING WITH SEN = 1 (RECEPTION, 7-BIT ADDRESSING)
SDA SCL SSPIF BF (SSPSTAT<0>)
SSPOV (SSPCON1<6>)
S
1 2 34 56 7 89 1 2345 67 89 1 2345 7 89
P
A7 A6 A5 A4 A3 A2 A1 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D1 D0
ACK
Receiving Data
ACK
Receiving Data
R/W
= 0
ACK
Receiving Address
Cleared in software
SSPBUF is read
Bus master terminates transfer
SSPOV is set because SSPBUF is still full. ACK is not sent.
D2
6
(PIR1<3>)
CKP (SSPCON1<4>)
CKP written to ‘1’ in
If BF is cleared prior to the falling edge of the 9th clock, CKP will not be reset to ‘0’ and no clock stretching will occur
software
Clock is held low until CKP is set to ‘1’
Clock is not held low because buffer full bit is clear prior to falling edge of 9th clock
Clock is not held low because ACK =
1
BF is set after falling edge of the 9th clock, CKP is reset to ‘0’ and clock stretching occurs