ATMEGA8A_14 Datasheet, PDF (171/320 Pages) ATMEL Corporation – 8-bit Atmel Microcontroller with 8KB In-System Programmable Flash

Figure 21-15. Formats and States in the Slave Receiver Mode
Reception of the own
slave address and one or
S
more data bytes. All are
acknowledged
SLA
W
A
DATA
$60
Last data byte received
is not acknowledged
Arbitration lost as master
and addressed as slave
Reception of the general call
address and one or more data
bytes
Last data byte received is
not acknowledged
A
$68
General Call
A
$70
DATA
Arbitration lost as master and
addressed as slave by general call
A
$78
A
DATA
A
P or S
$80
$80
$A0
A
P or S
$88
A
DATA
A
P or S
$90
$90
$A0
A
P or S
$98
From master to slave
From slave to master
DATA
n
Any number of data bytes
A
and their associated acknowledge bits
This number (contained in TWSR) corresponds
to a defined state of the Two-Wire Serial Bus. The
prescaler bits are zero or masked to zero
21.6.5 Slave Transmitter Mode
In the Slave Transmitter mode, a number of data bytes are transmitted to a Master Receiver (see Figure 21-16). All
the status codes mentioned in this section assume that the prescaler bits are zero or are masked to zero.
Figure 21-16. Data Transfer in Slave Transmitter Mode
V_CC
Device 1
Device 2
SLAVE
MASTER
Device 3 ........ Device n
R1
R2
TRANSMITTER
RECEIVER
SDA
SCL
To initiate the Slave Transmitter mode, TWAR and TWCR must be initialized as follows:
TWAR
value
TWA6
TWA5
TWA4
TWA3
TWA2
Device’s Own Slave Address
TWA1
TWA0
TWGCE
ATmega8A [DATASHEET]
8159E–AVR–02/2013
171