ez80f91 ZiLOG Semiconductor, ez80f91 Datasheet - Page 224

• Manufacturer Part Number: ez80f91
• Description: Ez80 Acclaimplus!? Connectivity Assp Ez80f91 Assp
• Manufacturer: ZiLOG Semiconductor

PS027001-0707
Clock Synchronization
All masters generate their own clocks on the SCL line to transfer messages on the I
Data is only valid during the High period of each clock.
Clock synchronization is performed using the wired AND connection of the I
to the SCL line, meaning that a High-to-Low transition on the SCL line causes the relevant
devices to start counting from their Low period. When a device clock goes Low, it holds
the SCL line in that state until the clock High state is reached. See
The Low-to-High transition of this clock, however, cannot change the state of the SCL
line if another clock is still within its Low period. The SCL line is held Low by the device
with the longest Low period. Devices with shorter Low periods enter a High wait state
during this time.
When all devices count off the Low period, the clock line is released and goes High. There
is no difference between the device clocks and the state of the SCL line; all of the devices
start counting the High periods. The first device to complete its High period again pulls
the SCL line Low. In this way, a synchronized SCL clock is generated with its Low period
determined by the device with the longest clock Low period, and its High period
determined by the device with the shortest clock High period.
by Transmitter
Data Output
Data Output
from Master
by Receiver
SCL Signal
START Condition
S
Clock Pulse for Acknowledge
Figure 46. I
MSB
1
1
2
2
C Acknowledge
8
9
Product Specification
Figure 47
I
2
C Serial I/O Interface
eZ80F91 ASSP
2
on page 217.
C interfaces
2
C bus.
216