Examples Of Jtag And Once Interaction - Motorola DSP56305 User Manual

1. Select shift-DR. Shift in the 24-bit "$0AF080" which is the opcode of the JUMP
instruction. Pass through update-DR to actually write the Instruction Latch.
2. Select shift-DR. Shift in the "Write PDB-GO-TO with GO and EX". Pass through
update-DR.
3. Select shift-DR. Shift in the 16 bit of "$xxxx". Pass through update-DR to actually
write the PDB. At this time the ODEC releases the chip from Debug mode and the
execution is started from the address $xxxx.
Note: If the Debug mode is entered during a DO LOOP, REP instruction, or other
special cases such as interrupt processing, STOP, WAIT, or conditional
branching, the user must first reset the DSP56300 and before proceeding with
the execution of the new program.

10.13 EXAMPLES OF JTAG AND OnCE INTERACTION

This subsection lists the details of the JTAG port/OnCE module interaction and TMS
sequencing required in order to achieve the communication described in Examples of
Using the OnCE on page 10-24.
The external command controller can force the DSP56300 into Debug mode by executing
the JTAG instruction DEBUG_REQUEST. In order to check that the DSP56300 has
entered the Debug mode, the external command controller must poll the status by
reading the OS[1:0] bits in the JTAG instruction shift register.
After executing the JTAG instructions DEBUG_REQUEST and ENABLE_ONCE and
after the core status was polled to verify that the chip is in Debug mode, the pipeline
saving procedure must take place. The TMS sequencing for this procedure is depicted in
Table 10-12.
MOTOROLA
Examples of JTAG and OnCE interaction
DSP56305 User's Manual
On-Chip Emulation Module
10-29