Chapter 36 Nexus Development Interface (NDI)
MPC5602P Microcontroller Reference Manual, Rev. 4
Freescale Semiconductor
921
Figure 36-16. CPU Scan Chain Register (CPUSCR)
36.12.8.1 Instruction Register (IR)
The Instruction Register (IR) provides a mechanism for controlling the debug session by serving as a
means for forcing in selected instructions, and then causing them to be executed in a controlled manner by
the debug control block. The opcode of the next instruction to be executed when entering debug mode is
contained in this register when the scan-out of this chain begins. This value should be saved for later
restoration if continuation of the normal instruction stream is desired.
On scan-in, in preparation for exiting debug mode, this register is filled with an instruction opcode selected
by debug control software. By selecting appropriate instructions and controlling the execution of those
instructions, the results of execution may be used to examine or change memory locations and processor
registers. The debug control module external to the processor core will control execution by providing a
single-step capability. Once the debug session is complete and normal processing is to be resumed, this
register may be loaded with the value originally scanned out.
TDO
TDI
TCK
MSR
WBBR
high
32
32
0
31
0
31
PC
32
0
31
IR
32
0
31
CTL
32
0
31
WBBR
low
32
0
31