Programming Information
49
Figure 3.5.14: Register 30h Bit Assignments
Table 3.5.15: Data Filter Register Definition
Programming
Example
For the programming example given, the following steps apply:
1.
Calculating f
D
:
f
D
= Demod DR x PCM Factor2
f
D
= 1000 x 1.5 = 1500 Hz
2.
Using the value for f
D
, select the K
0
, K
1
, and K
2
from the table:
K
0
= 0; K
1
= 6.53 x 10
-7
; K
2
= 9 x 10
-2
3.
Using the value for the coefficients, evaluate the formula:
Data Filter Value = (K
0
x f
D
3
) + (K
1
x f
D
2
) + (K
2
x f
D
)
Data Filter Value = 0 + 1.469 + 135
Data Filter Value = 136.47
4.
Round the value:
Data Filter Value = 136
5.
Convert the value to a hexadecimal number and write the value to register
30h:
Data Filter Value = 136 = 88h
7
6
5
4
3
2
1
0
0/1
0/1 0/1
0/1
0/1
0/1
0/1
0/1
Data Tuning Filter [Bit weight = 1] LSB
Data Tuning Filter [Bit weight = 2]
Data Tuning Filter [Bit weight = 4]
Data Tuning Filter [Bit weight = 8]
Data Tuning Filter [Bit weight = 16]
Data Tuning Filter [Bit weight = 32]
Data Tuning Filter [Bit weight = 64]
Data Tuning Filter [Bit weight = 128] MSB
Bit No.
Bit Name(s)
Functional Description
07-00
Data Filter
(Set bits according to the formula results. See above.)
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