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NUC126
Aug. 08, 2018
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Rev 1.03
NUC12
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Data Transfer on the I
2
C Bus
Figure 6.22-9 shows a master transmits data to slave. A master addresses a slave with a 7-bit address
and 1-bit write index to denote that the master wants to transmit data to the slave. The master keeps
transmitting data after the slave returns acknowledge to the master.
A = acknowledge (SDA low)
A = not acknowledge (SDA high)
S = START condition
P = STOP condition
‘0’ : write
S
SLAVE ADDRESS
R/W
A
DATA
A
DATA
A/A
P
from master to slave
from slave to master
data transfer
(n bytes + acknowlegde)
Figure 6.22-9 Master Transmits Data to Slave with a 7-bit address
Figure 6.22-10 shows a master read data from slave. A master addresses a slave with a 7-bit address
and 1-bit read index to denote that the master wants to read data from the slave. The slave will start
transmitting data after the slave returns acknowledge to the master.
‘1’ : read
S
SLAVE ADDRESS
R/W
A
DATA
A
DATA
A/A
P
data transfer
(n bytes + acknowlegde)
Figure 6.22-10 Master Reads Data from Slave with a 7-bit address
Figure 6.22-11 shows a master transmits data to slave by 10-bit address. A master addresses a slave
with a 10-bit address. First byte contains 10-
bit address indicator (5’b11110) and 2-bit address with
write index, second byte contains 8-bit address. The master keeps transmitting data after the second
byte end. Note that 7-bit and 10-bit address device can work on the same bus.
‘0’ : write
S
ADDRESS 1st byte
R/W
A
DATA
A
DATA
A/A
P
data transfer
(n bytes + acknowlegde)
ADDRESS 2nd byte
A
...
...
11110XX
Figure 6.22-11 Master Transmits Data to Slave by 10-bit address
Figure 6.22-12 shows a master read data from slave by 10-bit address. A master addresses a slave
with a 10-bit address. First mater transmits 10-bit address to slave, after that master transmits first byte
with read index. The slave will start transmitting data after the first byte with read index.