Datasheet

Section 18 I
2
C Bus Interface [Option]
(This function is not available in the H8S/2695)
Page 888 of 1434 R01UH0166EJ0600 Rev. 6.00
Mar 02, 2011
H8S/2633 Group, H8S/2633 F-ZTAT
TM
,
H8S/2633R F-ZTAT
TM
, H8S/2695
18.3.9 Noise Canceler
The logic levels at the SCL and SDA pins are routed through noise cancelers before being latched
internally. Figure 18.20 shows a block diagram of the noise canceler circuit.
The noise canceler consists of two cascaded latches and a match detector. The SCL (or SDA)
input signal is sampled on the system clock, but is not passed forward to the next circuit unless the
outputs of both latches agree. If they do not agree, the previous value is held.
System clock
period
Sampling clock
C
DQ
Latch
C
DQ
Latch
SCL or
SDA input
signal
Match
detector
Internal
SCL or
SDA
signal
Sampling
clock
Figure 18.20 Block Diagram of Noise Canceler