Rainbow Electronics ATmega128RFA1 - Manual (Page 393)

393
8266A-MCU Wireless-12/09
ATmega128RFA1
Figure 25-14. Formats and States in the Master Receiver Mode
S SLA R A DATA A
$08 $40 $50
SLA R
$10
A P
$48
A or A
$38
Other master
continues
$38
Other master
continues
W
A
$68
Other master
continues
$78 $B0
To corresponding
states in slave mode
MR
MT
Successfull
reception
from a slave
receiver
Next transfer
started with a
repeated start
condition
Not acknowledge
received after the
slave address
Arbitration lost in slave
address or data byte
Arbitration lost and
addressed as slave
DATA A
n
From master to slave
From slave to master
Any number of data bytes
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
P DATA A
$58
A
R
S
25.7.3 Slave Receiver Mode
In the Slave Receiver mode, a number of data bytes are received from a Master
Transmitter (see
Figure 25-15 below ). All the status codes mentioned in this section
assume that the prescaler bits are zero or are masked to zero.
Figure 25-15. Data transfer in Slave Receiver mode
Device 3 Device n
SDA
SCL
........ R1 R2
DEVDD
Device 2
MASTER
TRANSMITTER
Device 1
SLAVE
RECEIVER
To initiate the Slave Receiver mode, TWAR and TWCR must be initialized as follows:
TWAR TWA6 TWA5 TWA4 TWA3 TWA2 TWA1 TWA0 TWGCE
Value Device’s Own Slave Address