Serial Host Interface
Characteristics Of The I
2
C Bus
MOTOROLA
DSP56009 User’s Manual
5-21
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 5-8
).
• Stop data transfer—The Stop event is defined as a change in the state of the
data line, from low to high, while the clock is high (see
Figure 5-8
).
•
• Data valid—The state of the data line represents valid data when, after a Start
event, the data line is stable for the duration of the high period of the clock
signal. The data on the line may be changed during the low period of the clock
signal. There is one clock pulse per bit of data.
Each 8-bit word is followed by one acknowledge bit. This acknowledge bit is a high
level put on the bus by the transmitter when the master device generates an extra
acknowledge-related clock pulse. A slave receiver that is addressed is obliged to
generate an acknowledge after the reception of each byte. Also, a master receiver
must generate an acknowledge after the reception of each byte that has been clocked
out of the slave transmitter. The device that acknowledges has to pull down the SDA
line during the acknowledge clock pulse in such a way that the SDA line is stable low
during the high period of the acknowledge-related clock pulse (see
Figure 5-9
).
Figure 5-8 I
2
C Start and Stop Events
S
P
Start Event
Stop Event
SDA
SCL
AA0423
Summary of Contents for DSP56009
Page 19: ...MOTOROLA DSP56009 User s Manual 1 1 SECTION 1 OVERVIEW ...
Page 38: ...1 20 DSP56009 User s Manual MOTOROLA Overview DSP56009 Architectural Overview ...
Page 39: ...MOTOROLA DSP56009 User s Manual 2 1 SECTION 2 SIGNAL DESCRIPTIONS ...
Page 64: ...2 26 DSP56009 User s Manual MOTOROLA Signal Descriptions On Chip Emulation OnCETM Port ...
Page 65: ...SECTION 3 MEMORY OPERATING MODES AND INTERRUPTS ...
Page 85: ...MOTOROLA DSP56009 User s Manual 4 1 SECTION 4 EXTERNAL MEMORY INTERFACE ...
Page 149: ...MOTOROLA DSP56009 User s Manual 5 1 SECTION 5 SERIAL HOST INTERFACE ...
Page 180: ...5 32 DSP56009 User s Manual MOTOROLA Serial Host Interface SHI Programming Considerations ...
Page 181: ...MOTOROLA DSP56009 User s Manual 6 1 SECTION 6 SERIAL AUDIO INTERFACE ...
Page 207: ...MOTOROLA DSP56009 User s Manual 7 1 SECTION 7 GENERAL PURPOSE INPUT OUTPUT ...
Page 212: ...7 6 DSP56009 User s Manual MOTOROLA General Purpose Input Output GPIO Register GPIOR ...
Page 220: ...A 8 DSP56009 User s Manual MOTOROLA Bootstrap ROM Contents ...
Page 221: ...MOTOROLA DSP56009 User s Manual B 1 APPENDIX B PROGRAMMING REFERENCE ...
Page 250: ...B 30 DSP56009 User s Manual MOTOROLA Programming Reference ...
Page 251: ...MOTOROLA DSP56009 User s Manual C 1 APPENDIX C APPLICATION EXAMPLES ...
Page 262: ...C 12 DSP56009 User s Manual MOTOROLA Application Examples ...
Page 269: ...MOTOROLA DSP56009 User s Manual C 1 APPENDIX C APPLICATION EXAMPLES ...
Page 280: ...C 12 DSP56009 User s Manual MOTOROLA Application Examples ...