MC68HC908JK3 MOTOROLA [Motorola, Inc], MC68HC908JK3 Datasheet - Page 106

• Manufacturer Part Number: MC68HC908JK3
• Description: MC68HC908JK1
• Manufacturer: MOTOROLA [Motorola, Inc]

Monitor ROM (MON)
Technical Data
106
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
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.
Figure 9-2. Low-Voltage Monitor Mode Entry Flowchart
9.5
Monitor ROM (MON)
Security.) After the security bytes, the MCU sends a
MONITOR MODE
TRIGGERED?
POR RESET
IS VECTOR
EXECUTE
MONITOR
BLANK?
CODE
POR
YES
YES
NO
NO
NORMAL USER
MC68H(R)C908JL3
MODE
MOTOROLA
—
Rev. 1.0