MC68HC908QY2CDW Datasheet, PDF (139/184 Pages) Freescale Semiconductor, Inc – Microcontrollers

Monitor Module (MON)
15.3.1 Functional Description
Figure 15-9 shows a simplified diagram of monitor mode entry.
The monitor module receives and executes commands from a host computer. Figure 15-10, Figure 15-11,
and Figure 15-12 show example circuits used to enter monitor mode and communicate with a host
computer via a standard RS-232 interface.
POR RESET
CONDITIONS
FROM Table 15-1
NO
IRQ = V_TST?
YES
PTA0 = 1,
RESET VECTOR
BLANK?
YES
FORCED
MONITOR MODE
NO
NORMAL
USER MODE
HOST SENDS
8 SECURITY BYTES
PTA0 = 1,
NO
PTA1 = 1, AND
PTA4 = 0?
YES
NORMAL
MONITOR MODE
INVALID
USER MODE
IS RESET
POR?
NO
YES
YES
ARE ALL
SECURITY BYTES
NO
CORRECT?
ENABLE FLASH
DISABLE FLASH
MONITOR MODE ENTRY
DEBUGGING
AND FLASH
PROGRAMMING
(IF FLASH
IS ENABLED)
EXECUTE
MONITOR CODE
YES
DOES RESET
NO
OCCUR?
Figure 15-9. Simplified Monitor Mode Entry Flowchart
MC68HC908QY/QT Family Data Sheet, Rev. 6
Freescale Semiconductor
139