Programming Information
51
Figure 3.5.15: Register 31h Bit Assignments
Table 3.5.17: Low Pass Filter Register Definition
Programming
Example
For the programming example given, the following steps apply:
1.
Calculating f
L
:
f
L
= Demod f
c
+ (2 x Symbol Rate)
f
L
= 8000 + (2 x 1000) = 10000 Hz
2.
Using the value for f
L
, select the K
0
, K
1
, and K
2
from the table:
K
0
= 0; K
1
= 2.26 x 10
-8
; K
2
= 9.3 x 10
-3
3.
Using the value for the coefficients, evaluate the formula:
Low Pass Filter Value = (K
0
x f
L
3
) + (K
1
x f
L
2
) + (K
2
x f
L
)
Low Pass Filter Value = 0 + 2.26 + 93
Low Pass Filter Value = 95.26
4.
Round the value:
Low Pass Filter Value = 95
5.
Convert the value to a hexadecimal number and write the value to register
31h:
Low Pass Filter Value = 95 = 5Fh
7
6
5
4
3
2
1
0
0/1
0/1 0/1
0/1
0/1
0/1
0/1
0/1
Low Pass Tuning Filter [Bit weight = 1] LSB
Low Pass Tuning Filter [Bit weight = 2]
Low Pass Tuning Filter [Bit weight = 4]
Low Pass Tuning Filter [Bit weight = 8]
Low Pass Tuning Filter [Bit weight = 16]
Low Pass Tuning Filter [Bit weight = 32]
Low Pass Tuning Filter [Bit weight = 64]
Low Pass Tuning Filter [Bit weight = 128] MSB
Bit No.
Bit Name(s)
Functional Description
07-00
Low Pass Filter
(Set bits according to the formula results. See above.)
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
