Software Runaway Detect Function; Fig. 2.13.1 Sequence At Detecting Software Runaway Detection - Renesas 7200 Series User Manual

FUNCTIONAL DESCRIPTION

2.13 Software runaway detect function

2.13 Software runaway detect function
The M37221M6-XXXSP/FP has a function to decode undefined instructions to detect a software runaway.
When an undefined op-code is input to the CPU as an instruction code during operation of the M37221M6-
XXXSP/FP, the following processing is done.
The CPU generates an undefined instruction decoding signal.
The device is internally reset because of occurrence of the undefined instruction decoding signal.
As a result of internal reset, the same reset processing as in the case of ordinary reset operation is done,
and the program restarts from the reset vector.
Note, however, that the software runaway detecting function cannot be invalid.
φ
SYNC
Address
PC
Data
Undefined instruction decoding signal occurs.
Internal reset signal occurs.

Fig. 2.13.1 Sequence at detecting software runaway detection

2-90
? 01,S 01,S–1
? PC PC
H
7220 Group User's Manual
01,S–2 FFFE FFFF
16
PS AD
L L
Reset sequence
: Undefined instruction decode
? : Invalid
: Program counter
PC
S : Stack pointer
AD , AD : Jump destination address of reset
L H
AD ,
H
16
AD
L
AD
H