C protocol – Rainbow Electronics W90N745CDG User Manual
Page 343
W90N745CD/W90N745CDG
Publication Release Date: September 22, 2006
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339
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Revision
A2
6.14.1 I
2
C Protocol
Normally, a standard communication consists of four parts:
1) START or Repeated START signal generation
2) Slave address transfer
3) Data
transfer
4) STOP signal generation
SCL
SDA
S
or
Sr
MSB
ACK
P
or
Sr
P
Sr
LSB
MSB
LSB
1
2
7
8
9
1
2
3 - 7
8
9
A6
A5
A4 - A1
A0
R/W
D7
D6
D5 - D1
D0
NACK
ACK
Figure 6.14.1 Data transfer on the I
2
C-bus
S
SLAVE ADDRESS
R/W
A
DATA
A
DATA
A/A
P
'0'(write)
data transfer
(n bytes + acknowledge)
from master to slave
from slave to master
A = acknowledge (SDA low)
A = not acknowledge (SDA high)
S = START condition
P = STOP condition
A master-transmitter addressing a slave receiver with a 7-bit address
The transfer direction is not changed
'1'(read)
data transfer
(n bytes + acknowledge)
S
SLAVE ADDRESS
R/W
A
DATA
A
DATA
A
P
A master reads a slave immediately after the first byte (address)