mc68hc912dg128 Freescale Semiconductor, Inc, mc68hc912dg128 Datasheet - Page 91

• Manufacturer Part Number: mc68hc912dg128
• Description: M68hc12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

MC68HC912DG128 — Rev 3.0
MOTOROLA
CAUTION:
EXSTR1, EXSTR0 — External Access Stretch
ROMHM — FLASH EEPROM only in second Half of Map
Bit must be cleared before reading any of the arrays or registers.
ROMON — Enable FLASH EEPROM
Freescale Semiconductor, Inc.
This two bit field determines the amount of clock stretch on accesses
to the External Address Space. In Single Chip and Peripheral Modes
this bit has no meaning or effect.
This bit has no meaning if ROMON bit is clear.
In special mode, with ROMTST bit set, this bit will allow overlap of the
four 32K Flash EEPROM arrays and overlap the four 4-byte Flash
register space in the same map space to be able to program all arrays
at the same time.
These bits are used to enable the Flash EEPROM
For More Information On This Product,
0 = The 16K byte of fixed Flash EEPROM in location $4000–$7FFF
1 = Disables direct access to 16K byte Flash EEPROM from
0 = The four 32K Flash arrays are accessed with four pages for
1 = The four 32K Flash arrays coincide in the same space and are
0 = Disables Flash EEPROM in the memory map.
1 = Enables Flash EEPROM in the memory map.
can be accessed.
$4000–$7FFF in the memory map. The physical location of
this16K byte Flash can still be accessed through the Program
Page window.
each.
selected at the same time for programming.
Go to: www.freescale.com
Table 5-7. EXSTR Stretch Bit Definition
EXSTR1
Operating Modes
0
0
1
1
EXSTR0
0
1
0
1
Number of E Clocks
Stretched
0
1
2
3
Internal Resource Mapping
Operating Modes
Technical Data
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