rs5c338a RICOH Co.,Ltd., rs5c338a Datasheet - Page 22

• Manufacturer Part Number: rs5c338a
• Description: 3-wire Serial Interface Real-time Clock Ics With Voltage Monitoring Function
• Manufacturer: RICOH Co.,Ltd.

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1.2 Data Transfer Formats
Data transfer is commenced in the low to high transition of the CE pin input and completed in its high to low
transition. Data transfer is conducted serially in multiple units of 1 byte (8 bits). The former 4 bits are used to
specify in the address pointer a head address with which data transfer is to be commenced from the host. The latter
4 bits are used to select either reading data transfer or writing data transfer and set the transfer format register to
specify an appropriate data transfer format. All data transfer formats are designed to transfer the most significant bit
(MSB) first.
Two types of data transfer formats are available for reading data transfer and writing data transfer each.
1.3 Writing Data Transfer Formats
1.3-1 1-byte Writing Data Transfer Format
The first type of writing data transfer format is designed to transfer 1-byte data at a time and can be selected by
specifying in the address pointer a head address with which writing data transfer is to be commenced and then
writing the setting of 8h to the transfer format register. This 1-byte writing data transfer can be completed by
driving the CE pin low or continued by specifying a new head address in the address pointer and setting the transfer
format.
Example of 1-byte Writing Data Transfer (For Writing Data to Addresses Fh and 7h)
×
CE
SCLK
SIO
5C338A
CE
SIO
Specifying Fh
in the address
pointer
1 1 1 1 1
A3
1
Setting the address
A2
2
pointer
Setting 8h
in the transfer
format register
Data transfer from the host
A1
0
3
0
A0
0
4
Writing data
to address Fh
C3
5
Setting the transfer
format register
Data
C2
6
C1
7
C0
8
Specifying 7h
in the address
pointer
0 1 1 1
D7
1
Data transfer from the real-time clocks
D6
2
Setting 8h
in the transfer
format register
1
Reading data transfer
Writing data transfer /
0
3
0 0
Writing data
to address 7h
D3
Data
D2
D1
D0