BU94501AMUV Datasheet, PDF (26/73 Pages) Rohm – AAC/WMA/MP3 +SD Memory Card + iPod

BU9450xAxxx series
Datasheet
9. I²C command interface
Slave I²C serial interface
Signal name I/O
Function
SCL
I I²C interface clock input
SDA
I/O I²C interface data I/O
Remarks
External pull-up resistor is required.
External pull-up resistor is required.
This is an I²C serial interface terminal to communicate with the microcomputer (master).
It supports slave I²C operations.
9.1 I²C protocol
When the I2C bus is in the IDLE state, SDA and SCL are set to H by the external Pull-up resistor.
To start communications, the master sets SDA to L while SCL set to H (Start condition).
To finish communications, the master sets SDA to H while SCL set to H (Stop condition). During transfer, the
master changes SDA only while SCL is L. Figure 25. shows Start condition and Stop condition of I²C.
Figure 25. I²C Start and Stop Conditions
9.2 Slave address
I²C bus slave addresses support the 7-bit addressing mode.
Figure 26. shows the slave address transfer format.
S
A6
A5
A4
A3
A2
A1
A0 R/W ACK
Start
condition
Slave Address
R / W = Read / Write Pulse
ACK = Acknowledge
sent by
slave
Figure 26. Slave Address Transfer Format
Table 5. Settable Slave Addresses
MSB
A5 A4 A3 A2 A1
LSB
A0
10000
1
1
9.3 Protocol to write from the master
When sending commands from the master using the I²C bus, be sure to conform to the transfer protocol shown in
Figure 27.
S Slave Address R/W A Data(8bit) A Data(8bit) A
"0"(write)
From Master to Slave
From Slave to Master
A = Acknowledge(SDA low)
A = No Acknowledge(SDA high)
S = Start Condition
P = Stop condition
Figure 27. Command Send Protocol
Data(8bit)
A/A P
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2012.12.10 Rev.003