W79E804ADG 参数 Datasheet PDF下载

W79E804A/803A/802A

24.3.3 Slave Receiver Mode

Serial data and the serial clock are received through SDA and SCL. After each byte is received, an

acknowledge bit is transmitted. START and STOP conditions are recognized as the beginning and

end of a serial transfer. Address recognition is performed by hardware after reception of the slave

address and direction bit.

24.3.4 Slave Transmitter Mode

The first byte is received and handled as in the slave receiver mode. However, in this mode, the

direction bit will indicate that the transfer direction is reversed. Serial data is transmitted via SDA while

the serial clock is input through SCL. START and STOP conditions are recognized as the beginning

and end of a serial transfer.

24.4 Data Transfer Flow in Five Operating Modes

The five operating modes are: Master/Transmitter, Master/Receiver, Slave/Transmitter,

Slave/Receiver and GC Call. Bits STA, STO and AA in I2CON register will determine the next state of

the SIO hardware after SI flag is cleared. Upon complexion of the new action, a new status code will

be updated and the SI flag will be set. If the I2C interrupt control bits (EA and EI2) are enable,

appropriate action or software branch of the new status code can be performed in the Interrupt service

routine.

Data transfers in each mode are shown in the following figures.

*** Legend for the following five figures:

Software's access to S1DAT with respect to "Expected next action":

08H

(1) Data byte will be transmitted:

A START has been

Software should load the data byte (to be transmitted)

transmitted.

into S1DAT before new S1CON setting is done.

(2) SLA+W (R) will be transmitted:

Software should load the SLA+W/R (to be transmitted)

into S1DAT before new S1CON setting is done.

(STA,STO,SI,AA)=(0,0,0,X)

(3) Data byte will be received:

Software can read the received data byte from S1DAT

SLA+W will be transmitted;

while a new state is entered.

ACK bit will be received.

Last state

Last action is done

Next setting in S1CON

Expected next action

New state

next action is done

18H

SLA+W has been transmitted;

ACK has been received.

Figure 24-3: Legen for the following four figures

- 99 -

Publication Release Date: July 16, 2007

Revision A2