M68HC16 Z SERIES
MASKED ROM MODULE
USER’S MANUAL
7-3
Refer to
for more information concerning access times.
7.5 Low-Power Stop Mode Operation
Low-power stop mode minimizes MCU power consumption. Setting the STOP bit in
MRMCR places the MRM in low-power stop mode. In low-power stop mode, the array
cannot be accessed. The reset state of STOP is the complement of the logic state of
DATA14 during reset. Low-power stop mode is exited by clearing STOP.
7.6 ROM Signature
Signature registers RSIGHI and RSIGLO contain a user-specified mask-programmed
signature pattern. A user-specified signature algorithm provides the capability to verify
ROM array contents.
7.7 Reset
The state of the MRM following reset is determined by the default values programmed
into the MRMCR BOOT, LOCK, ASPC[1:0], and WAIT[1:0] bits. The default array
base address is determined by the values programmed into ROMBAL and ROMBAH.
When the mask programmed value of the MRMCR BOOT bit is zero, the contents of
MRM bootstrap words ROMBS[0:3] are used as reset vectors. When the mask pro-
grammed value of the MRMCR BOOT bit is one, reset vectors are fetched from exter-
nal memory, and system integration module chip-select logic is used to assert the boot
ROM select signal CSBOOT. Refer to
5.9.4 Chip-Select Reset Operation
for more
information concerning external boot ROM selection.
Table 7-2 Wait States Field
WAIT[1:0]
Number of
Wait States
Clocks per Transfer
00
0
3
01
1
4
10
2
5
11
–1
2
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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