MC912DG128A Motorola, MC912DG128A Datasheet - Page 250

• Manufacturer Part Number: MC912DG128A
• Description: Microcontrollers
• Manufacturer: Motorola

IIC System Configuration
IIC Protocol
Inter-IC Bus
MC68HC912DT128A Rev 2.0
250
SDA
SCL
SDA
SCL
Signal
Signal
Start
Start
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
The IIC 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. 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: START
signal, slave address transmission, data transfer and STOP signal. They
are described briefly in the following sections and illustrated in
4
4
5
5
Figure 38 IIC Transmission Signals
6
6
7
7
Read/
Write
Read/
Write
LSB
LSB
8
8
Ack
Ack
Bit
9
9
Bit
Inter-IC Bus
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
5
5
D2
6
6
D1
7
7
Read/
Write
LSB
LSB
D0
8
8
Ack
No
Bit
Ack
No
9
9
Bit
Signal
MOTOROLA
Figure
Stop
Signal
Stop
4-iicbus
38.