On-Chip Emulation Module
Trace Buffer
MOTOROLA
DSP56305 User’s Manual
10-21
10.9.3
OnCE PAB Register for Execute (OPABEX)
The OnCE PAB Register for Execute (OPABEX) is a 16-bit register that stores the address
of the instruction currently in the Instruction Latch. This is the instruction that would
have been decoded and executed if the chip would not have entered the Debug mode.
The OPABEX register can only be read through the JTAG port. This register is not
affected by the operations performed during the Debug mode.
10.9.4
Trace Buffer
The Trace buffer stores the addresses of the last twelve change of flow instructions that
were executed, as well as the address of the last executed instruction. The Trace buffer is
implemented as a circular buffer containing twelve 17-bit registers and one 4-bit counter.
All the registers have the same address, but any read access to the Trace buffer address
causes the counter to increment, thus pointing to the next Trace buffer register. The
registers are serially available to the external command controller through their common
Trace buffer address. Figure 10-10 on page 10-22 shows the block diagram of the Trace
buffer. The Trace buffer is not affected by the operations performed during the Debug
mode except for the Trace buffer pointer increment when reading the Trace buffer.
When entering the Debug mode, the Trace buffer counter is pointing to the Trace buffer
register containing the address of the last executed instructions. The first Trace buffer
read obtains the oldest address and the following Trace buffer reads get the other
addresses from the oldest to the newest, in order of execution.
Notes:
1.
To ensure Trace buffer coherence, a complete set of twelve reads of the
Trace buffer must be performed. This is necessary due to the fact that each
read increments the Trace buffer pointer, thus pointing to the next
location. After twelve reads, the pointer indicates the same location as
before starting the read procedure.
2.
On any change of flow instruction, the Trace buffer stores both the address
of the change of flow instruction, as well as the address of the target of the
change of flow instruction. In the case of conditional change of flows, the
address of the change of flow instruction is always stored (regardless of the
fact that the change of flow is true or false), but if the conditional change of
flow is false (i.e., not taken) the address of the target is not stored. In order
to facilitate the program trace reconstruction, every Trace buffer location
has an additional ‘invalid bit’ (the 25th bit). If a conditional change of flow
instruction has a ‘condition false’, the invalid bit is set, thus marking this
instruction as not taken. Therefore, it is imperative to read seventeen bits of
Summary of Contents for DSP56305
Page 34: ...xxxii DSP56305 User s Manual MOTOROLA ...
Page 40: ...xxxvi DSP56305 User s Manual MOTOROLA ...
Page 41: ...MOTOROLA DSP56305 User s Manual 1 1 SECTION 1 DSP56305 OVERVIEW ...
Page 58: ...1 18 DSP56305 User s Manual MOTOROLA DSP56305 Overview DSP56305 Architecture Overview ...
Page 59: ...MOTOROLA DSP56305 User s Manual 2 1 SECTION 2 SIGNAL CONNECTION DESCRIPTIONS ...
Page 98: ...2 40 DSP56305 User s Manual MOTOROLA Signal Connection Descriptions JTAG OnCE Interface ...
Page 99: ...MOTOROLA DSP56305 User s Manual 3 1 SECTION 3 MEMORY CONFIGURATION ...
Page 119: ...MOTOROLA DSP56305 User s Manual 4 1 SECTION 4 CORE CONFIGURATION ...
Page 144: ...4 26 DSP56305 User s Manual MOTOROLA Core Configuration JTAG Boundary Scan Register BSR ...
Page 145: ...MOTOROLA DSP56305 User s Manual 5 1 SECTION 5 GENERAL PURPOSE I O ...
Page 149: ...HOST INTERFACE HI32 MOTOROLA DSP56305 User s Manual 6 1 SECTION 6 HOST INTERFACE HI32 ...
Page 150: ...6 2 DSP56305 User s Manual MOTOROLA HOST INTERFACE HI32 ...
Page 259: ...MOTOROLA DSP56305 User s Manual 7 1 SECTION 7 ENHANCED SYNCHRONOUS SERIAL INTERFACE ESSI ...
Page 315: ...MOTOROLA DSP56305 User s Manual 8 1 SECTION 8 SERIAL COMMUNICATION INTERFACE SCI ...
Page 347: ...MOTOROLA DSP56305 User s Manual 9 1 SECTION 9 TIMER EVENT COUNTER ...
Page 376: ...9 30 DSP56305 User s Manual MOTOROLA Timer Event Counter Timer Modes of Operation ...
Page 377: ...MOTOROLA DSP56305 User s Manual 10 1 SECTION 10 ON CHIP EMULATION MODULE ...
Page 411: ...MOTOROLA DSP56305 User s Manual 11 1 SECTION 11 JTAG PORT ...
Page 430: ...11 20 DSP56305 User s Manual MOTOROLA JTAG Port DSP56305 Boundary Scan Register ...
Page 431: ...Filter Co Processor MOTOROLA DSP56305 User s Manual 12 1 SECTION 12 FILTER CO PROCESSOR ...
Page 471: ...VITERBI CO PROCESSOR MOTOROLA DSP56305 User s Manual 13 1 SECTION 13 VITERBI CO PROCESSOR ...
Page 522: ...13 52 DSP56305 User s Manual MOTOROLA VITERBI CO PROCESSOR References ...
Page 554: ...14 32 DSP56305 User s Manual MOTOROLA CYCLIC CODE CO PROCESSOR Configuration Examples ...
Page 555: ...MOTOROLA DSP56305 User s Manual A 1 APPENDIX A BOOTSTRAP CODE ...
Page 568: ...A 14 DSP56305 User s Manual MOTOROLA Bootstrap Code ...
Page 569: ...Equates MOTOROLA DSP56305 User s Manual B 1 APPENDIX B EQUATES ...
Page 589: ...MOTOROLA DSP56305 User s Manual C 1 APPENDIX C JTAG BSDL ...
Page 590: ...C 2 DSP56305 User s Manual MOTOROLA JTAG BSDL ...
Page 600: ...C 12 DSP56305 User s Manual MOTOROLA JTAG BSDL ...
Page 601: ...MOTOROLA DSP56305 User s Manual D 1 APPENDIX D PROGRAMMING REFERENCE ...
Page 602: ...D 2 DSP56305 User s Manual MOTOROLA PROGRAMMING REFERENCE ...
Page 661: ...Y MOTOROLA DSP56305 User s Manual Index 11 ...
Page 662: ...Y Index 12 DSP56305 User s Manual MOTOROLA ...