C8051F342 データシートの表示（PDF） - Silicon Laboratories

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C8051F342

Full Speed USB Flash MCU Family

Silicon Laboratories 

C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D

17.5.3. Slave Receiver Mode

Serial data is received on SDA and the clock is received on SCL. When slave events are enabled (INH =

0), the interface enters Slave Receiver Mode when a START followed by a slave address and direction bit

(WRITE in this case) is received. Upon entering Slave Receiver Mode, an interrupt is generated and the

ACKRQ bit is set. Software responds to the received slave address with an ACK, or ignores the received

slave address with a NACK. If the received slave address is ignored, slave interrupts will be inhibited until

the next START is detected. If the received slave address is acknowledged, zero or more data bytes are

received. Software must write the ACK bit after each received byte to ACK or NACK the received byte. The

interface exits Slave Receiver Mode after receiving a STOP. Note that the interface will switch to Slave

Transmitter Mode if SMB0DAT is written while an active Slave Receiver. Figure 17.7 shows a typical Slave

Receiver sequence. Two received data bytes are shown, though any number of bytes may be received.

Notice that the ‘data byte transferred’ interrupts occur before the ACK cycle in this mode.

Interrupt

S

SLA

WA

Data Byte

A

Data Byte

AP

Interrupt

Received by SMBus

Interface

Transmitted by

SMBus Interface

Interrupt

Interrupt

S = START

P = STOP

A = ACK

W = WRITE

SLA = Slave Address

Figure 17.7. Typical Slave Receiver Sequence

Rev. 1.3

201

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