Datasheet

Monitor ROM (MON)
MC68HC908GZ16 • MC68HC908GZ8 Data Sheet, Rev. 4
Freescale Semiconductor 277
Figure 20-8. Simplified Monitor Mode Entry Flowchart
MONITOR MODE ENTRY
POR RESET
PTA0 = 1, PTA1 = 0,
PTB0 = 1, AND
PTB1 = 0?
IRQ = V
TST
?
PTA0 = 1,
PTA1 = 0, RESET
VECTOR BLANK?
YES
NO
YES
NO
FORCED
MONITOR MODE
NORMAL
USER MODE
NORMAL
MONITOR MODE
INVALID
USER MODE
NO NO
HOST SENDS
8 SECURITY BYTES
IS RESET
POR?
YES
YES
YES
NO
ARE ALL
SECURITY BYTES
CORRECT?
NO
YES
ENABLE FLASH
DISABLE FLASH
EXECUTE
MONITOR CODE
DOES RESET
OCCUR?
CONDITIONS
FROM Table 20-1
DEBUGGING
AND FLASH
PROGRAMMING
(IF FLASH
IS ENABLED)