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CHAPTER 18 SERIAL INTERFACE IIC0 (
μ
PD780078Y SUBSERIES ONLY)
User
’
s Manual U14260EJ3V1UD
(2) IIC status register 0 (IICS0)
This register indicates the status of I
2
C.
IICS0 is read by a 1-bit or 8-bit memory manipulation instruction.
RESET input clears IICS0 to 00H.
Figure 18-6. Format of IIC Status Register 0 (IICS0) (1/3)
Address: FFA9H After reset: 00H R
Symbol
7
6
5
4
3
2
1
0
IICS0
MSTS0
ALD0
EXC0
COI0
TRC0
ACKD0
STD0
SPD0
MSTS0
Master device status
0
Slave device status or communication standby status
1
Master device communication status
Condition for clearing (MSTS0 = 0)
Condition for setting (MSTS0 = 1)
When a stop condition is detected
When ALD0 = 1 (arbitration loss)
Cleared by LREL0 = 1 (exit from communications)
When IICE0 changes from 1 to 0 (operation stop)
When RESET is input
When a start condition is generated
ALD0
Detection of arbitration loss
0
This status means either that there was no arbitration or that the arbitration result was a
“
win
”
.
1
This status indicates the arbitration result was a
“
loss
”
. MSTS0 is cleared.
Condition for clearing (ALD0 = 0)
Condition for setting (ALD0 = 1)
Automatically cleared after IICS0 is read
Note
When IICE0 changes from 1 to 0 (operation stop)
When RESET is input
When the arbitration result is a
“
loss
”
.
EXC0
Detection of extension code reception
0
Extension code was not received.
1
Extension code was received.
Condition for clearing (EXC0 = 0)
Condition for setting (EXC0 = 1)
When a start condition is detected
When a stop condition is detected
Cleared by LREL0 = 1 (exit from communications)
When IICE0 changes from 1 to 0 (operation stop)
When RESET is input
When the higher 4 bits of the received
address data are either
“
0000
”
or
“
1111
”
(set at the rising edge of the eighth clock).
Note
This register is also cleared when a bit manipulation instruction is executed for bits other than IICS0.
Remark
LREL0: Bit 6 of IIC control register 0 (IICC0)
IICE0:
Bit 7 of IIC control register 0 (IICC0)