MC68HC908LJ24 Datasheet, PDF (170/464 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Monitor ROM (MON)
POR RESET
IS VECTOR ^NO
BLANK?
YES
MONITOR MODE
NORMAL USER
MODE
EXECUTE
MONITOR
CODE
POR
NO
TRIGGERED?
YES
Figure 10-2. Low-Voltage Monitor Mode Entry Flowchart
In monitor mode, the MCU uses different vectors for reset, SWI
(software interrupt), and break interrupt than those for user mode. The
alternate vectors are in the $FE page instead of the $FF page and allow
code execution from the internal monitor firmware instead of user code.
NOTE:
Exiting monitor mode after it has been initiated by having a blank reset
vector requires a power-on reset (POR). Pulling RST low will not exit
monitor mode in this situation.
Table 10-2 summarizes the differences between user mode and monitor
mode vectors.
Modes
User
Monitor
Table 10-2. Mode Differences (Vectors)
Reset
Vector
High
$FFFE
$FEFE
Reset
Vector
Low
$FFFF
$FEFF
Functions
Break
Vector
High
Break
Vector
Low
$FFFC $FFFD
$FEFC $FEFD
SWI
Vector
High
$FFFC
$FEFC
SWI
Vector
Low
$FFFD
$FEFD
Data Sheet
170
MC68HC908LJ24/LK24 — Rev. 2
Monitor ROM (MON)
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