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POWER MANAGEMENT

SC900A

flexibility, in that once the slave address has been sent to the SC900A enabling it to be a slave transmitter/receiver,

any register can be written to or read from independently of each other. While there is no auto increment/decrement

dent of which register you have been accessing. The start and stop commands frame the datapacket and the repeat

start condition is allowed if necessary.

Seven-bit addressing is required for communication with the SC900A; ten-bit addressing is not allowed. Any general

call address will be ignored by the SC900A. Note that the SC900A is not CBUS compatible. Finally, the SC900A can

operate in standard mode (100kbit/s) or fast mode (400kbit/s).

Supported Formats

Direct Format - Write

sponds with an 8-bit data byte consisting of the register address. The slave acknowledges and the master sends the

appropriate 8-bit data byte. Once again the slave acknowledges and the master terminates the transfer with the stop

condition [P].

Slave Address

Register Address

Data

S

W A

AA P

S: Start Condition

Slave Address: 7 bit

W: Write = ‘0’

Register Address: 8 bit

A: Acknowledge (sent by slave)

Data: 8 bit

P: Stop condition

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Combined Format - Read

then acknowledges that it is being addressed, and the master responds with an 8-bit data byte consisting of the reg-

ister address. The slave acknowledges and the master sends the repeated start condition [Sr]. Once again the slave

address is sent, followed by an eighth bit indicating a read. The slave responds with an acknowledge and the previ-

ously addressed 8-bit data byte. The master then sends a non-acknowledge (NACK). Finally the master terminates the

transfer with the stop condition [P].

Slave Address

Register Address

Slave Address

Data

NACK

S

W A

A Sr

R A

P

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)

NACK: Non-Acknowledge (sent by master)

Sr: Repeated Start Condition

P: Stop condition

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Applications Information (Cont.)