314
CHAPTER 18 I
2
C BUS MODE (
µ
PD784225Y SUBSERIES ONLY)
User’s Manual U12697EJ3V0UM
Figure 18-13. Wait Signal (2/2)
(2) Both the master and slave have 9 clock waits
(Master: transmitting, Slave: receiving, ACKE0 = 1)
Master
Slave
Transfer lines
IIC0
SCL0
6
7
8
9
2
3
Both the master and slave wait
after nine clocks are output.
IIC0
←
data (wait release)
IIC0
←
FFH or WREL0
←
1
IIC0
SCL0
SCL0
SDA0
D2
D1
6
7
8
9
1
2
3
D0
ACK
D6
D5
ACKE0
H
D7
Output in accordance with the preset ACKE0
1
Remark
ACKE0: Bit 2 in I
2
C bus control register 0 (IICC0)
WREL0: Bit 5 in I
2
C bus control register 0 (IICC0)
A wait is automatically generated by setting bit 3 (WTIM0) of I
2
C bus control register 0 (IICC0).
Normally, when bit 5 (WREL0) = 1 in IICC0 or FFH is written to serial shift register 0 (IIC0), the receiving side
releases the wait; when data is written to IIC0, the transmitting side releases the wait.
In the master, the wait can be released by the following methods.
•
IICC0 bit 1 (STT0) = 1
•
IICC0 bit 0 (SPT0) = 1