PIC18F4550-IP Datasheet, PDF (224/438 Pages) Microchip Technology – 28/40/44-Pin, High-Performance, Enhanced Flash, USB Microcontrollers with nanoWatt Technology

PIC18F2455/2550/4455/4550
19.4.4.5 Clock Synchronization and
the CKP bit
When the CKP bit is cleared, the SCL output is forced
to ‘0’. However, clearing the CKP bit will not assert the
SCL output low until the SCL output is already
sampled low. Therefore, the CKP bit will not assert the
SCL line until an external I²C master device has
already asserted the SCL line. The SCL output will
remain low until the CKP bit is set and all other
devices on the I²C bus have deasserted SCL. This
ensures that a write to the CKP bit will not violate the
minimum high time requirement for SCL (see
Figure 19-14).
FIGURE 19-14: CLOCK SYNCHRONIZATION TIMING
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
SDA
SCL
CKP
Write
SSPCON1
DX
Master device
asserts clock
Master device
deasserts clock
DX – 1
DS39632E-page 222
© 2009 Microchip Technology Inc.