87
AT89C51ID2
4289C–8051–11/05
Table 66. Status in Master Transmitter Mode
Status
Code
SSSTA
Status of the Two-
wire Bus and Two-
wire Hardware
Application software response
Next Action Taken by Two-wire Hardware
To/From SSDAT
To SSCON
SSSTA
SSSTO
SSI
SSAA
08h
A START condition has
been transmitted
Write SLA+W
X
0
X
SLA+W will be transmitted.
10h
A repeated START
condition has been
transmitted
Write SLA+W
Write SLA+R
X
0
X
SLA+W will be transmitted.
SLA+R will be transmitted.
Logic will switch to master receiver mode
18h
SLA+W has been
transmitted; ACK has
been received
Write data byte
No SSDAT action
0
1
0
1
0
1
0
X
Data byte will be transmitted.
Repeated START will be transmitted.
STOP condition will be transmitted and SSSTO flag
will be reset.
STOP condition followed by a START condition will
be transmitted and SSSTO flag will be reset.
20h
SLA+W has been
transmitted; NOT ACK
has been received
Write data byte
No SSDAT action
0
1
0
1
0
1
0
X
Data byte will be transmitted.
Repeated START will be transmitted.
STOP condition will be transmitted and SSSTO flag
will be reset.
STOP condition followed by a START condition will
be transmitted and SSSTO flag will be reset.
28h
Data byte has been
transmitted; ACK has
been received
Write data byte
No SSDAT action
0
1
0
1
0
1
0
X
Data byte will be transmitted.
Repeated START will be transmitted.
STOP condition will be transmitted and SSSTO flag
will be reset.
STOP condition followed by a START condition will
be transmitted and SSSTO flag will be reset.
30h
Data byte has been
transmitted; NOT ACK
has been received
Write data byte
No SSDAT action
0
1
0
1
0
1
0
X
Data byte will be transmitted.
Repeated START will be transmitted.
STOP condition will be transmitted and SSSTO flag
will be reset.
STOP condition followed by a START condition will
be transmitted and SSSTO flag will be reset.
38h
Arbitration lost in
SLA+W or data bytes
No SSDAT action
0
1
0
X
Two-wire bus will be released and not addressed
slave mode will be entered.
A START condition will be transmitted when the bus
becomes free.
