R2025S/D
(4) Data Transmission Write Format in the R2025S/D
Although the I2C-Bus standard defines a transmission format for the slave allocated for each IC, transmission
method of address information in IC is not defined. The R2025S/D transmits data the internal address pointer
(4bit) and the Transmission Format Register (4bit) at the 1byte next to one which transmitted a Slave Address and
a write command. For write operation only one transmission format is available and (0000) is set to the
Transmission Format Register. The 3byte transmits data to the address specified by the internal address pointer
written to the 2byte. Internal address pointer setting are automatically incremented for 4byte and after. Note that
when the internal address pointer is Fh, it will change to 0h on transmitting the next byte.
Example of data writing (When writing to internal address Eh to Fh)
R/W=0(Write)
Data
Data
S 0 1 1 0 0 1 0 0 A 1 1 1 0 0 0 0 0 A
A
A P
Slave Address
Address Transmission Writing of data to the Writing of data to the
←(0110010)
Pointer
←Eh
Format
Register ←
0h
internal address Eh
internal address Fh
Master to slave
Start Condition
Slave to master
Stop Condition
S
A
P
Acknowledge signal
A
/A
(5) Data transmission read format of the R2025S/D
The R2025S/D allows the following three read out method of data an internal register.
The first method to reading data from the internal register is to specify an internal address by setting the internal
address pointer and the transmission format register described P24 (4), generate the Repeated Start Condition
(See P23 (3)) to change the data transmission direction to perform reading. The internal address pointer is set to
Fh when the Stop Condition is met. Therefore, this method of reading allows no insertion of Stop Condition before
the Repeated Start Condition. Set 0h to the Transmission Format Register when this method used.
24
RICOH [ RICOH ELECTRONICS DEVICES DIVISION ]
