External Memory Interface
EMI Operating Considerations
MOTOROLA
DSP56009 User’s Manual
4-39
• If an access is being processed (EBSY = 1), an additional trigger can be
generated. This trigger will be considered pending if:
– the address calculation is executed overlapping the last I
cyc
of the current
access, and/or
– the external access immediately follows, thus providing full bus
bandwidth.
• EBAR is incremented and updated (if EINR = 1 for read, or EINW = 1 for
write) one I
cyc
after the address calculation time frame.
• Following a read access, the data is available on EDRR, and can be read by the
DSP core:
– SRAM modes—at the first I
cyc
after completing the external access
– Fast DRAM mode—at the last I
cyc
of the external access
– Slow DRAM mode—at the I
cyc
after the last I
cyc
of the external access
Special consideration should be given when triggering a new access after two read
accesses since the EMI Data Register Buffer (EDRB) can be full if the EMI Data Read
Register (EDRR) is also full. In this case the new trigger will remain pending and the
new access will not take place until the EDRB is empty. The status of the EDRB can be
verified by checking the ECSR EBDF flag. If EBDF = 0 after a read operation, the
EDRB is empty and it is possible to start a new access immediately. Figure 4-8
illustrates the EMI pipeline.
Figure 4-8 EMI Pipeline
I
–1
I0
I
1
I
2
I
3
IN–1 IN
IN+1 IN+2 IN+3
EBAR trig2
EDRR
trig3
comp1 incr1
comp2 incr2
Data Access # 1
Data Access # 2
trig1
I
cyc
Flow
Core Operation
EMI Operation
EBSY
External Access
AA0300k
read
read
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 ...