Rainbow Electronics W90N745CDG - Manual (Page 343)

W90N745CD/W90N745CDG
Publication Release Date: September 22, 2006
- 339 - 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)