ez80l92 ZiLOG Semiconductor, ez80l92 Datasheet - Page 148

• Manufacturer Part Number: ez80l92
• Description: Ez80acclaim Flash Microcontrollers
• Manufacturer: ZiLOG Semiconductor

PS013014-0107
Clock Synchronization
slave-transmitter must release the data line to allow the master to generate a STOP or a
repeated START condition.
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
High transition of this clock, however, may not 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 long-
est Low period. Devices with shorter Low periods enter a High wait-state during this time.
When all devices concerned count off their 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, and
all of the devices start counting their 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 one 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 33. I
MSB
1
1
2
2
C Acknowledge
8
9
Product Specification
Figure
I
2
C Serial I/O Interface
34. The Low-to-
2
C interfaces
2
C bus.
142