RV5C339A_03 Datasheet, PDF (22/46 Pages) RICOH electronics devices division – 3-WIRE SERIAL INTERFACE REAL-TIME CLOCK IC WITH VOLTAGE MONITORING FUNCTION

RV5C339A
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.
CE
SCLK
SIO
12345678123
A3 A2 A1 A0 C3 C2 C1 C0 D7 D6
D3 D2 D1 D0
Setting the address
pointer
Setting the transfer
format register
Writing data transfer /
Reading data transfer
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
SIO
11111000
Data
Specifying Fh Setting 8h
in the address in the transfer
pointer
format register
Writing data
to address Fh
0111 1000
Data
Specifying 7h Setting 8h
in the address in the transfer
pointer
format register
Writing data
to address 7h
Data transfer from the host
Data transfer from the real-time clocks
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