mc9s08ac16 Freescale Semiconductor, Inc, mc9s08ac16 Datasheet - Page 240

• Manufacturer Part Number: mc9s08ac16
• Description: Hcs08 Microcontrollers 8-bit Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 13 Inter-Integrated Circuit (S08IICV2)
13.4.1.1
When the bus is free, no master device is engaging the bus (SCL and SDA lines are at logical high), a
master may initiate communication by sending a start signal. As shown in
defined as a high-to-low transition of SDA while SCL is high. This signal denotes the beginning of a new
data transfer (each data transfer may contain several bytes of data) and brings all slaves out of their idle
states.
13.4.1.2
The first byte of data transferred immediately after the start signal is the slave address transmitted by the
master. This is a seven-bit calling address followed by a R/W bit. The R/W bit tells the slave the desired
direction of data transfer.
Only the slave with a calling address that matches the one transmitted by the master responds by sending
back an acknowledge bit. This is done by pulling the SDA low at the ninth clock (see
No two slaves in the system may have the same address. If the IIC module is the master, it must not transmit
an address equal to its own slave address. The IIC cannot be master and slave at the same time. However,
if arbitration is lost during an address cycle, the IIC reverts to slave mode and operates correctly even if it
is being addressed by another master.
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1 = Read transfer, the slave transmits data to the master.
0 = Write transfer, the master transmits data to the slave.
SCL
SDA
SCL
SDA
Signal
Signal
Start
Start
Start Signal
Slave Address Transmission
msb
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
msb
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
1
1
2
2
Calling Address
Calling Address
3
3
4
4
5
5
Figure 13-9. IIC Bus Transmission Signals
MC9S08AC16 Series Data Sheet, Rev. 0
6
6
7
7
Read/
Read/
Write
Write
lsb
lsb
8
8
PRELIMINARY
Ack
Ack
Bit
Bit
9
9
XX
Repeated
XXX
Signal
Start
msb
msb
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
D7
1
1
D6
2
2
New Calling Address
D5
3
3
Data Byte
D4
4
4
D3
Figure
5
5
D2
6
6
13-9, a start signal is
D1
7
7
Freescale Semiconductor
Read/
Write
Figure
lsb
lsb
D0
8
8
Ack
No
Bit
Ack
No
9
Bit
9
13-9).
Signal
Stop
Signal
Stop