mc68hc908ap8cfa Freescale Semiconductor, Inc, mc68hc908ap8cfa Datasheet - Page 119

• Manufacturer Part Number: mc68hc908ap8cfa
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Enter monitor mode with pin configuration shown in
rising edge of RST latches monitor mode. Once monitor mode is latched, the values on the specified pins
can change.
Once out of reset, the MCU waits for the host to send eight security bytes. (See
security bytes, the MCU sends a break signal (10 consecutive logic 0’s) to the host, indicating that it is
ready to receive a command.
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.
Table 8-2
Freescale Semiconductor
summarizes the differences between user mode and monitor mode vectors.
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.
Monitor
Modes
User
Figure 8-2. Low-Voltage Monitor Mode Entry Flowchart
Table 8-2. Mode Differences (Vectors)
Vector
$FFFE
$FEFE
Reset
High
MC68HC908AP Family Data Sheet, Rev. 4
MONITOR MODE
TRIGGERED?
POR RESET
IS VECTOR
EXECUTE
MONITOR
BLANK?
CODE
Vector
POR
$FFFF
$FEFF
Reset
Low
YES
YES
NOTE
NO
Figure 8-1
NO
$FEFC
Vector
$FFFC
Break
High
Functions
NORMAL USER
Vector
$FFFD
$FEFD
Break
by pulling RST low and then high. The
Low
MODE
$FEFC
Vector
$FFFC
High
SWI
8.4
Vector
$FFFD
$FEFD
Functional Description
Security.) After the
Low
SWI
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