Texas Instruments MSP430x1xx User Manual page 321

2
15.2.3 I C Addressing Modes
The I
7-Bit Addressing
In the 7-bit addressing format, shown in Figure 15−5, the first byte is the 7-bit
slave address and the R/W bit. The ACK bit is sent from the receiver after each
byte.
2
Figure 15−5. I C Module 7-Bit Addressing Format
1
7
S Slave Address
10-Bit Addressing
In the 10-bit addressing format, shown in Figure 15−6, the first byte is made
up of 11110b plus the two MSBs of the 10-bit slave address and the R/W bit.
The ACK bit is sent from the receiver after each byte. The next byte is the
remaining 8 bits of the 10-bit slave address, followed by the ACK bit and the
8-bit data.
2
Figure 15−6. I C Module 10-Bit Addressing Format
1
7
S Slave Address 1st byte
1 1 1 1 0 X X
Repeated START Conditions
The direction of data flow on SDA can be changed by the master, without first
stopping a transfer, by issuing a repeated START condition. This is called a
RESTART. After a RESTART is issued, the slave address is again sent out with
the new data direction specified by the R/W bit. The RESTART condition is
shown in Figure 15−7.
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Figure 15−7. I C Module Addressing Format with Repeated START Condition
1 1
7
S Slave Address R/W ACK
1
2
C module supports 7-bit and 10-bit addressing modes.
1 1
8
R/W ACK Data
1 1
8
R/W ACK Slave Address 2nd byte
1 1 1
8
Data ACK S Slave Address
Any
Number
1
8
ACK Data
1
8
ACK Data
1 1
7
R/W ACK
1
USART Peripheral Interface, I
2
I C Module Operation
1 1
ACK P
1 1
ACK P
1 1
8
Data ACK P
Any Number
2
C Mode 15-7