AN2408 Freescale Semiconductor / Motorola, AN2408 Datasheet - Page 9

• Manufacturer Part Number: AN2408
• Description: Examples of HCS12 External Bus Design A Companion Note to AN2287/D
• Manufacturer: Freescale Semiconductor / Motorola

Figure 8
x + 8, x + 16, x + 24 pages, as only ADDR19 is used for decoding, and ADDR17 and ADDR18 are not
implemented.
Freescale Semiconductor
ECLK
R/W
PB0
PB1
PB2
PB3
PB4
PB5
PB6
PB7
PA0
PA1
PA2
PA3
PA4
PA5
PA6
PA7
PK0
PK1
PK2
PK3
PK4
PK5
Memory Map
details memory implementation of Example #3. Notice the external memory will mirror from x to
ADDR/DATA0
ADDR/DATA1
ADDR/DATA2
ADDR/DATA3
ADDR/DATA4
ADDR/DATA5
ADDR/DATA6
ADDR/DATA7
ADDR/DATA8
ADDR/DATA9
ADDR/DATA10
ADDR/DATA11
ADDR/DATA12
ADDR/DATA13
ADDR/DATA14
ADDR/DATA15
XADDR14
XADDR15
XADDR16
XADDR19
0000
FFFF
30
3F
31
32
ADDR/DATA8
ADDR/DATA9
ADDR/DATA10
ADDR/DATA11
ADDR/DATA12
ADDR/DATA13
33
XADDR14
XADDR15
XADDR16
XADDR19
34
Figure 7. Byte-Wide SRAM Interface with Paging
GND
35
Examples of HCS12 External Bus Design, Rev. 2
36
Figure 8. Memory Map of
37
Internal Flash
10
11
13
2
3
4
5
6
7
8
9
1
38
2
3
1
U10
74FCT821/SO
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
CLK
OE
U12A
74FCT139A/SO
A
B
G
39
3A
Q10
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Q8
Q9
Y 0
Y 1
Y 2
Y 3
3B
23
22
21
20
19
18
17
16
15
14
4
5
6
7
3C
3D
ADDR8
ADDR9
ADDR10
ADDR11
ADDR12
ADDR13
ADDR14
ADDR15
ADDR16
3E
Example #3 — Byte-Wide SRAM Interface with Paging
3F
Figure 7
PPAGE
ADDR/DATA0
ADDR/DATA1
ADDR/DATA2
ADDR/DATA3
ADDR/DATA4
ADDR/DATA5
ADDR/DATA6
ADDR/DATA7
ADDR8
ADDR9
ADDR10
ADDR11
ADDR12
ADDR13
ADDR14
ADDR15
ADDR16
00
08
10
18
01
09
11
19
02
0A
12
1A
External RAM
Note: Shadow Pages
12
11
10
27
26
23
25
28
31
24
29
22
30
XADDR19
03
0B
13
1B
9
8
7
6
5
4
3
2
U11
AS7C1024/SOJ
1
0
0
0
0
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
OE
WE
CE1
CE2
04
0C
14
1C
R/W
05
0D
15
1D
X
0
0
1
1
ECLK
I/O0
I/O1
I/O2
I/O3
I/O4
I/O5
I/O6
I/O7
06
0E
16
1E
X
0
1
0
1
07
0F
17
1F
13
14
15
17
18
19
20
21
OE
1
1
1
1
0
WE
ADDR/DATA8
ADDR/DATA9
ADDR/DATA10
ADDR/DATA11
ADDR/DATA12
ADDR/DATA13
ADDR/DATA14
ADDR/DATA15
1
1
0
1
1
9