MC908JL16CFAE FREESCALE [Freescale Semiconductor, Inc], MC908JL16CFAE Datasheet - Page 187

• Manufacturer Part Number: MC908JL16CFAE
• Description: Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Figure
IRQ = V
Enter monitor mode with the pin configuration shown above by pulling RST low and then high. The 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 zeros) to the host, indicating that it is
ready to receive a command. The break signal also provides a timing reference to allow the host to
determine the necessary baud rate.
In monitor mode, the MCU uses different vectors for reset, SWI, and break interrupt. 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 16-2
Freescale Semiconductor
16-9. shows a simplified diagram of the monitor mode entry when the reset vector is blank and
DD
. An OSC1 frequency of 9.8304MHz is required for a baud rate of 9600.
is a summary of the vector differences between user mode and monitor mode.
Monitor
Modes
Notes:
1. If the high voltage (V
User
COP enable output. The COP is a mask option enabled or disabled by the COPD bit in the
configuration register.
Figure 16-9. Low-Voltage Monitor Mode Entry Flowchart
Disabled
Enabled
COP
Table 16-2. Monitor Mode Vector Differences
(1)
TST
MC68HC908JL16 Data Sheet, Rev. 1.1
) is removed from the IRQ pin or the RST pin, the SIM asserts its
Vector
$FEFE
$FFFE
Reset
High
MONITOR MODE
TRIGGERED?
POR RESET
IS VECTOR
EXECUTE
MONITOR
BLANK?
CODE
POR
YES
YES
Vector
$FEFF
$FFFF
Reset
Low
NO
NO
Functions
Vector
$FFFC
$FEFC
Break
High
NORMAL USER
MODE
Vector
$FFFD
$FEFD
Break
Low
Vector
$FFFC
$FEFC
High
SWI
16.3.8
Monitor Module (MON)
Security.) After the
$FEFD
Vector
$FFFD
Low
SWI
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