7220 Datasheet, PDF (195/303 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
5.4 Example of I²C-BUS interface control (M37221Mx-XXXSP/FP)
5.4.3 E²PROM functions
(1) Byte write
Bytes are written by sending the START condition, slave address “A016,” sub-address (1 byte), data
(1 byte), and the STOP condition from the master. Writing to the E²PROM will be started after the
master sends the STOP condition, that is, in synchronization with a rising edge of the SDA signal.
This writing will be automatically terminated by the on-chip sequential controller. In this period, no
acknowledge bits are generated.
Figure 5.4.2 shows the byte write timing.
S
Bus operation of T
master side:
A
R
T
Slave
address (W)
Sub-address (n)
SDA signal S
W
S
Data (n)
T
O
P
P
Bus operation of
slave side:
A
A
A
C
C
C
K
K
K
S : START condition
P : STOP condition
ACK : Acknowledge bit
W : Write bit (0)
Fig. 5.4.2 Byte write timing
(2) Random address read
In this mode, the data of an arbitrary address is read. To set the first-read address, the master sends
the START condition, slave address “A016,” and sub-address (1 byte). Upon receiving the acknowledge
bit (ACK) from the E²PROM, the master sends the RESTART condition signal and slave address
“A116” again. After ACK is generated from the E²PROM, the data of the corresponding sub-address
is read out.
After the data is output, no acknowledge bits are generated, but the STOP condition is sent by the
master, completing this read operation.
S
Bus operation of
T
A
master side: R
T
Slave
address (W)
Sub-address (n)
S
T
A
R
Slave
address
(R)
T
SDA signal S
W
R
R
S
Bus operation of
slave side:
A
A
A
C
C
C
K
K
K
S : START condition
R : Read bit (1)
P : STOP condition
RS : RESTART condition
ACK : Acknowledge bit NACK : No acknowledge bit
W : Write bit (0)
Fig. 5.4.3 Random address read timing
N
AS
CT
KO
P
P
Data (n)
5-22
7220 Group User’s Manual