Chapter 36 Nexus Development Interface (NDI)
MPC5602P Microcontroller Reference Manual, Rev. 4
Freescale Semiconductor
927
External logic may monitor the assertion of these signals for debugging purposes. Watchpoints are
signaled in the clock cycle following the occurrence of the actual event. The module also
monitors assertion of these signals for various development control purposes.
36.14 Basic Steps for Enabling, Using, and Exiting External Debug
Mode
The following steps show one possible scenario for a debugger wishing to use the external debug facilities.
This simplified flow is intended to illustrate basic operations, but does not cover all potential methods in
depth.
Enabling External Debug Mode and initializing Debug registers
•
The debugger should ensure that the
jd_en_once
control signal is asserted in order to enable OnCE
operation
•
Select the OCR and write a value to it in which OCR
DR
, OCR
WKUP
, are set to ‘1’. The tap
controller must step through the proper states as outlined earlier. This step will place the CPU in a
debug state in which it is halted and awaiting single-step commands or a release to normal mode
•
Scan out the value of the OSR to determine that the CPU clock is running and the CPU has entered
the Debug state. This can be done in conjunction with a Read of the CPUSCR. The OSR is shifted
out during the Shift_IR state. The CPUSCR will be shifted out during the Shift_DR state. The
debugger should save the scanned-out value of CPUSCR for later restoration.
Table 36-15. Watchpoint Output Signal Assignments
Signal Name
Type
Description
jd_watchpt[0]
IAC1
Instruction Address Compare 1 watchpoint
Asserted whenever an IAC1 compare occurs regardless of being enabled
to set DBSR status
jd_watchpt[1]
IAC2
Instruction Address Compare 2 watchpoint
Asserted whenever an IAC2 compare occurs regardless of being enabled
to set DBSR status
jd_watchpt[2]
IAC3
Instruction Address Compare 3 watchpoint
Asserted whenever an IAC3 compare occurs regardless of being enabled
to set DBSR status
jd_watchpt[3]
IAC4
Instruction Address Compare 4 watchpoint
Asserted whenever an IAC4 compare occurs regardless of being enabled
to set DBSR status
jd_watchpt[4]
DAC1
1
1
If the corresponding event is completely disabled in DBCR0, either load-type or store-type data accesses are
allowed to generate watchpoints, otherwise watchpoints are generated only for the enabled conditions.
Data Address Compare 1 watchpoint
Asserted whenever a DAC1 compare occurs regardless of being enabled
to set DBSR status
jd_watchpt[5]
DAC2
Data Address Compare 2 watchpoint
Asserted whenever a DAC2 compare occurs regardless of being enabled
to set DBSR status