SC900
POWER MANAGEMENT
Applications Information (Cont.)
Stop Separated Reads
Another read format is available which is, in effect, an extension of the combined format read. This format allows
a master to set up the register address pointer for a read and return to that slave some time later to read the data.
After the start condition [S], the slave address is sent, followed by a write. The SC900 I2C then acknowledges that
it is being addressed, and the master responds with the 8-bit register address. The master then sends a stop or
restart condition, and may address another slave. Some time later the master sends a start or restart condition,
and a valid slave address is sent, followed by a read. The SC900 I2C then acknowledges and returns the data at the
register address location that had previously been set up.
II22CCSStotopp Separated Format - Read
Register Address Setup Access
Master Addresses
other Slaves
Register Read Access
S Slave Address AW A Register Address A P S Slave Address B
S/
Sr
Slave
Address
AR
A
Data
S : Start Condition
Slave Address : 7 bit
W: Write = '0'
Register Address : 8 bit
R : Read = '1'
Data : 8 Bit
A : Acknowledge (sent by slave)
B : Acknowledge (sent by master)
Sr: Repeated Start Condition
P : Stop Condition
BP
2005 Semtech Corp.
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