BU9873 Datasheet, PDF (12/40 Pages) Rohm – I2C BUS Serial Interface RTC with High-precision Oscillation Adjustment

BU9873
Datasheet
1-5. Write Command
Write command is illustrated as following: Firstly, input start condition; then, enter the 7-bit slave address. Slave address of
――
this IC is (0110010). Thereafter, enter “L” for the R/W bit, which indicates the direction of data transmission.
In the next byte, input the internal address pointer (4-bit) and transmission format (4-bit) to the IC. For write operation, only
one transmission format (0000) is available. The 3_rd byte transmits data that will be written to the address specified by the
internal address pointer. Internal address pointer settings will also be automatically incremented for 4byte and after. Note
that when the internal address pointer is Fh, it will change to 0h during transmitting the next byte.
Example of write command (when writing to internal address Eh to Fh)
SDA
LINE
S
T
A
Slave
R
Addr ess
T
0 1 1 0 0 1 00
Internal
Address Transmission
Pointer Format
1 1 1 0 0 0 0 0 D7
DATA
D0 D7
DATA
S
T
O
P
D0
RA
A
A
A
/C
C
C
C
K
K
K
K
W
Figure 18. Write command
1-6. Read Command
This IC allows the following three methods of reading data from an internal register.
1-6-1. Read from a Specified Internal Address
The first method uses data write command to specify the internal address pointer and transfer format, and then repeat the
start condition again. After the 7-bit slave address, enter “H” for the R/ W bit, which indicates the direction of data
transmission. In the next byte, data from the specified internal address will be output. 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.
The internal address pointer is reset to Fh when a stop condition is met. Therefore, this read method allows no insertion of
stop condition before the end of read.
Example 1 of data read (when data is read from 2h to 3h)
S
T
A
Slave
R
Address
T
Internal
Address
Pointer
S
Transmission
T
A
Format
R
T
Slave
Address
SDA
LINE
0 1 1 0 0 1 0 0 0 01 0 0 0 00
0 1 1 0 0 1 0 1 ^D7
RA
A
RA
/C
C
/C
K
W
K
K
W
DATA
Figure 19. Read from a specified internal address
D0 D7
A
C
K
S
T
DATA
O
P
D0
A
C
K
www.rohm.com
© 2013 ROHM Co., Ltd. All rights reserved.
TSZ22111・15・001
12/37
TSZ02201-0919AGZ00010-1-2
13.Sep.2013 REV.001