CHAPTER 10 SERIAL INTERFACE FUNCTION
User’s Manual U13850EJ6V0UD
342
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ACKEn
Acknowledge control
0
Disable acknowledge.
1
Enable acknowledge. During the ninth clock period, the SDA line is set to low level. However, the ACK is
invalid during address transfers and is valid when EXCn = 1.
Condition for clearing (ACKEn = 0)
Note
Condition for setting (ACKEn = 1)
•
Cleared by instruction
•
When RESET is input
•
Set by instruction
STTn
Start condition trigger
0
Does not generate a start condition.
1
When bus is released (in STOP mode):
Generates a start condition (for starting as master). The SDAn line is changed from high level to low
level and then the start condition is generated. Next, after the rated amount of time has elapsed, SCLn
is changed to low level.
When bus is not used:
•
When communication reservation function is enabled (IICRSVn = 0)
Functions as the start condition reservation flag. When set, automatically generates a start condition
after the bus is released.
•
When communication reservation function is disabled (IICRSVn = 1)
The STCFn bit is set. No start condition is generated.
In the wait state (when master device)
Generates a restart condition after releasing the wait.
Cautions concerning set timing
•
For master reception:
Cannot be set during transfer. Can be set only when ACKEn has been set to 0 and slave
has been notified of final reception.
•
For master transmission: A start condition cannot be generated normally during the ACKn period. Set during the wait
period.
•
For slave:
The communication reserved status is entered even if the communication reservation
function is disabled (IICRSVn = 1).
•
Cannot be set at the same time as SPTn
Condition for clearing (STTn = 0)
Condition for setting (STTn = 1)
•
Cleared by loss in arbitration
•
Cleared after start condition is generated by master
device
•
When LRELn = 1
•
When IICEn = 0
•
Cleared when RESET is input
•
Set by instruction
Note
This flag’s signal is invalid when IICEn = 0.
Remarks 1.
Bit 1 (STTn) is 0 if it is read immediately after data setting.
2.
IICRSVn: Bit 0 of IIC flag register n (IICFn)
STCFn:
Bit 7 of IIC flag register n (IICFn)
3.
n = 0, 1
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