599
I
2
C Bus (IIC)
Chapter 18
Preliminary User’s Manual U17566EE1V2UM00
18.6.6
Wait signal (WAIT)
The wait signal (WAIT) is used to notify the communication partner that a
device (master or slave) is preparing to transmit or receive data (i.e., is in a
wait state).
Setting the SCLn pin to low level notifies the communication partner of the wait
status. When the wait status has been cancelled for both the master and slave
devices, the next data transfer can begin.
(1)
When master device has a nine-clock wait and slave device has an eight-
clock wait (master: transmission, slave: reception, and IICCn.ACKEn
bit = 1)
Figure 18-11
Wait signal (1/2)
S
CLn
6
S
DAn
7
8
9
1
2
3
S
CLn
IICn
6
H
7
8
1
2
3
D2
D1
D0
ACK
D7
D6
D5
9
IICn
S
CLn
ACKEn
M
as
ter (Tx)
M
as
ter ret
u
rn
s
to high
imped
a
nce
bu
t
s
l
a
ve
i
s
in w
a
it
s
t
a
te (low level).
W
a
it
a
fter o
u
tp
u
t
of ninth clock.
IICn d
a
t
a
write (c
a
ncel w
a
it)
S
l
a
ve (Rx)
W
a
it
a
fter o
u
tp
u
t
of eighth clock.
FFH i
s
written to IICn regi
s
ter or
IICCn.WRELn
b
it i
s
s
et to 1.
Tr
a
n
s
fer line
s
W
a
it
s
ign
a
l
from
s
l
a
ve
W
a
it
s
ign
a
l
from m
as
ter
electronic components distributor