Serial Host Interface
Characteristics Of The I
2
C Bus
MOTOROLA
DSP56367
9-19
HBUSY is cleared otherwise. HBUSY is cleared by hardware reset, software reset, SHI
individual reset, and during the stop state.
9.6
CHARACTERISTICS OF THE I
2
C BUS
The I
2
C serial bus consists of two bidirectional lines, one for data signals (SDA) and one for
clock signals (SCL). Both the SDA and SCL lines must be connected to a positive supply
voltage via a pull-up resistor.
Note:
In the I
2
C bus specifications, the standard mode (100 kHz clock rate) and a fast
mode (400 kHz clock rate) are defined. The SHI can operate in either mode.
9.6.1
OVERVIEW
The I
2
C bus protocol must conform to the following rules:
•
Data transfer may be initiated only when the bus is not busy.
•
During data transfer, the data line must remain stable whenever the clock line is high.
Changes in the data line when the clock line is high are interpreted as control signals
(see Figure 9-7).
Figure 9-7 I
2
C Bit Transfer
Accordingly, the I
2
C bus protocol defines the following events:
•
Bus not busy—Both data and clock lines remain high.
•
Start data transfer—The start event is defined as a change in the state of the data
line, from high to low, while the clock is high (see Figure 9-8).
SDA
SCL
Data Line
Stable:
Data Valid
Change
of Data
Allowed
AA0422
Содержание DSP56367
Страница 16: ...xvi MOTOROLA CONTENTS Paragraph Number Title Page Number ...
Страница 22: ...xxii MOTOROLA List of Figures Figure Number Title Page Number ...
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Страница 148: ...4 6 DSP56367 MOTOROLA Design Considerations PLL Performance Issues ...
Страница 248: ...9 30 DSP56367 MOTOROLA Serial Host Interface SHI Programming Considerations ...
Страница 306: ...10 58 DSP56367 MOTOROLA Enhanced Serial Audio Interface ESAI ESAI Initialization Examples ...
Страница 389: ...Bootstrap ROM Contents MOTOROLA DSP56367 A 15 end ...
Страница 390: ...A 16 DSP56367 MOTOROLA Bootstrap ROM Contents ...
Страница 432: ...C 8 DSP56367 MOTOROLA JTAG BSDL ...
Страница 484: ...D 52 DSP56367 MOTOROLA Programmer s Reference ...
Страница 490: ...E 6 DSP56367 MOTOROLA Power Consumption Benchmark ...
Страница 516: ...F 26 DSP56367 MOTOROLA IBIS Model ...
Страница 522: ...Index 6 MOTOROLA Index ...
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