BU9873 Datasheet, PDF (13/40 Pages) Rohm – I2C BUS Serial Interface RTC with High-precision Oscillation Adjustment

BU9873
Datasheet
1-6-2. Fast Read from a Specified Internal Address (with changing transmission format)
The second method uses data write command to specify the internal address pointer, but the transfer format is designated
to be (0100). In the next byte, data from the specified internal address will be output immediately. If entering “L” during the
timing of ACK, the data from the next address will be output continuously. The read operation will not be ended until entering
“H” during the timing of ACK and following a stop condition.
Example 2 of data read (when data is read from internal addresses Eh to 1h)
SDA
LINE
S
T
A
Slave
R
Address
T
01100100
Internal
Address Transmission
Pointe r Format
1 1 1 0 0 1 0 0 D7
DATA
DATA
D0 D7
RA
A
A
/C
C
C
K
K
K
W
Figure 20. Fast read from a specified internal address
D0 D7
A
C
K
S
T
DATA
O
P
D0
A
C
K
1-6-3. Read from Address Fh (without specifying the internal address)
The third method starts with a start condition, and then enters the 7-bit slave address and “H” for the R/ W bit, which
indicates the direction of data transmission.
In the next byte, data from address Fh will be output immediately. If entering “L” during the timing of ACK, the data from
the next address will be output continuously. The read operation will not be ended until entering “H” during the timing of ACK
and following a stop condition
Since the internal address pointer is set to Fh by a stop condition, this method is only effective when reading is started
from the internal address Fh.
Example 3 of data read (when data is read from internal addresses Fh to 3h)
SDA
LINE
S
T
A
Slave
R
Address
T
0 1 1 0 0 1 0 1 D7
RA
/C
K
W
DATA
DATA
DATA
DATA
D0 D7
D0 ^D7
A
A
C
C
K
K
Figure 21. Read from address Fh
D0 D7
A
C
K
D0 D7
A
C
K
S
T
DATA
O
P
D0
A
C
K
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