Chapter 3 - Installing Instrument Boards
81
Figure 3-10: Example 2 address switches
Example 3: Base Address range spanning 32 addresses
with offset
This example uses a base address range of 220H-23FH (spanning a
boundary between 32 base addresses) and offset of A800H.
1. Set the base address.
The base address of 220H-23FH in binary becomes
10,0010,0000 through 10,0011,1111. This translates in settings
of (remember that A0-A3 are ignored)
A9 A8 A7 A6 A5 A4
1 0
0 0 1 0
through
A9 A8 A7 A6 A5 A4
1 0
0 0 1 1
2. Set the offset address.
The offset address of A800H in binary becomes
1010,1000,0000,0000, which means settings of:
A15 A14 A13 A12 A11 A10 A9 A8 A7 A6 A5 A4
1 0 1 0
1 0 0 0
0 0 0 0
3. Set the address mask.
Since A4 and A5 are used in the internal decoding, we will
have to set A4EN = OFF and A5EN = OFF.
ADDRESS
MASK
OFFSET ADDRESS
BASE ADDRESS
ENABLE
DISABLE
SW2
SW1
0
1
Off
On
On
On
Off
On
Off
On
A
4
A5
A6
A7
A8
A9
A1
0
A1
1
A1
2
A1
3
On
On
On
Off
Off
Off
Off
A1
4
A1
5
A4
EN
A5
EN
A1
0E
N
A1
1E
N
A1
2E
N
70
2E
N
Pn
PE
N
16
Bi
tE
N
0
1
Off
Off
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