S9S08AW16A FREESCALE [Freescale Semiconductor, Inc], S9S08AW16A Datasheet - Page 235

• Manufacturer Part Number: S9S08AW16A
• Description: HCS08 Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

13.4
This section provides a complete functional description of the IIC module.
13.4.1
The IIC bus system uses a serial data line (SDA) and a serial clock line (SCL) for data transfer. All devices
connected to it must have open drain or open collector outputs. A logic AND function is exercised on both
lines with external pull-up resistors. The value of these resistors is system dependent.
Normally, a standard communication is composed of four parts:
The stop signal should not be confused with the CPU stop instruction. The IIC bus system communication
is described briefly in the following sections and illustrated in
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.
Freescale Semiconductor
•
•
•
•
SCL
SDA
SCL
SDA
Start signal
Slave address transmission
Data transfer
Stop signal
Functional Description
Signal
Signal
Start
Start
IIC Protocol
Start Signal
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. 8
6
6
7
7
Read/
Read/
Write
Write
lsb
lsb
8
8
Ack
Ack
Bit
9
Bit
9
XX
Repeated
XXX
Signal
Start
msb
msb
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
D7
1
1
Figure
D6
2
2
New Calling Address
D5
3
3
13-9.
Data Byte
D4
4
4
D3
Figure
5
5
Inter-Integrated Circuit (S08IICV2)
D2
6
6
13-9, a start signal is
D1
7
7
Read/
Write
lsb
lsb
D0
8
8
Ack
No
Bit
Ack
No
9
Bit
9
Signal
Stop
Signal
Stop
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