Chapter 36 Nexus Development Interface (NDI)
MPC5602P Microcontroller Reference Manual, Rev. 4
920
Freescale Semiconductor
CPU to exit the state and enter the debug mode once the CPU clock
m_clk
has been restored. Note that in
this case, the CPU will negate the
p_waiting, p_halted
and
p_stopped
outputs. Once the debug session
has ended, the CPU will return to the state it was in prior to entering debug mode.
To signal the chip-level clock generator to re-enable
m_clk
, the
p_wakeup
output will be asserted
whenever the debug block is asserting a debug request to the CPU due to OCR
DR
being set, or
jd_de_b
assertion, and will remain set from then until the debug session ends (
jd_debug_b
goes from asserted to
negated). In addition, the status of the
jd_mclk_on
input (after synchronization to the
j_tclk
clock
domain) may be sampled along with other status bits from the
j_tdo
output during the Shift_IR TAP
controller state. This status may be used if necessary by external debug firmware to ensure proper scan
sequences occur to registers in the
m_clk
clock domain.
36.12.7.5 Software Request During Normal Activity
Upon executing a ‘
bkpt’
pseudo
-
instruction (for e200z0h, defined to be an all 0’s instruction opcode)
when the OCR register’s (FDB) bit is set (debug mode enable control bit is true), and DBCR0
EDM
=1, the
CPU enters the debug mode after the instruction following the ‘
bkpt’
pseudo
-
instruction has entered the
instruction register.
36.12.8 CPU Status and Control Scan Chain Register (CPUSCR)
A number of on-chip registers store the CPU pipeline status and are configured in a single scan chain for
access by the e200z0h OnCE controller. The CPUSCR register contains these processor resources, which
are used to restore the pipeline and resume normal chip activity upon return from the debug mode, as well
as a mechanism for the emulator software to access processor and memory contents. Figure 36-16 shows
the block diagram of the pipeline information registers contained in the CPUSCR. Once debug mode has
been entered, it is required to scan in and update this register prior to exiting debug mode.