Operating Modes
68HC(9)12DG128 Rev 1.0
70
Operating Modes
MOTOROLA
indices are used to point to one of eight different 16K byte pages. They
can be viewed as expanded addresses x16, x15 and x14.
* The 16K byte program space page 6 can also be accessed at a fixed
location from $4000 to $7FFF. The 16K byte program space page 7 can
also be accessed at a fixed location from $C000 to $FFFF.
Flash register
space expansion
(68HC912DG128
only)
There are four 32K Flash arrays for 68HC912DG128 and each requires
a 4-byte register block. A register space window is used to access one
of the four 4-byte blocks and the PPAGE register to map each one into
the window. The register space window is located from $00F4 to $00F7
after reset. Only two page indices are used to point to one of the four
pages of the register space.
Table 13 Program space Page Index
Page Index 2
(PPAGE bit 2)
0
0
0
0
1
1
1
1
Page Index 1
(PPAGE bit 1)
0
0
1
1
0
0
1
1
Page Index 0
(PPAGE bit 0)
0
1
0
1
0
1
0
1
16K Program space
Page
16K byte Page 0
16K byte Page 1
16K byte Page 2
16K byte Page 3
16K byte Page 4
16K byte Page 5
16K byte Page 6*
16K byte Page 7*
Flash array
68HC912DG128
00FEE32K
00FEE32K
01FEE32K
01FEE32K
10FEE32K
10FEE32K
11FEE32K
11FEE32K
ROM array
68HC12DG128
00ROM32K
00ROM32K
01ROM32K
01ROM32K
10ROM32K
10ROM32K
11ROM32K
11ROM32K
Table 14 Flash Register space Page Index
Page Index 2
(PPAGE bit
2)
0
0
1
1
Page Index 1
(PPAGE bit 1)
Page Index 0
(PPAGE bit 0)
Flash register space Page
Flash array
0
1
0
1
X
X
X
X
$00F4-$00F7 Page 0
$00F4-$00F7 Page 1
$00F4-$00F7 Page 2
$00F4-$00F7 Page 3
00FEE32K
01FEE32K
10FEE32K
11FEE32K
12-modes