W79E825A Datasheet, PDF (108/127 Pages) Winbond – 8-BIT MICROCONTROLLER

W79E825A/824A/823B/822B Data Sheet
25.3.4 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.
25.4 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:
Last state
Last action is done
Next setting in S1CON
Expected next action
Software's access to S1DAT with respect to "Expected next action":
08H
A START has been
transmitted.
(1) Data byte will be transmitted:
Software should load the data byte (to be 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:}
SLA+Wwill be transmitted; Software can read the received data byte fromS1DAT
ACK bit will be received.
while a new state is entered.
New state
next action is done
18H
SLA+W has been transmitted;
ACK has been received.
Figure 25-3: Legen for the following four figures
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