Programming Information
39
The value programmed into the registers are based on the following equation:
Register Value = Demod f
c
x
214.74837
Results are rounded to the nearest integer and then cleaved into four separate
bytes as shown in
Figure 3.5.6
.
Table 3.5.6: Demodulator Quadrature NCO Group Register Definition
Programming
Example
1.
For the programming example given, the following equation must be
evaluated:
Register Value = Demod f
c
x 214.74837
Register Value = 8000 x 214.74837 = 1717986.96
2.
Rounding results as shown below:
Register Value = 1717987
3.
By successively dividing the above value by the bit weight values shown in
figure above, the appropriate hexadecimal equivalent can be obtained:
Register Value = 001A36E3h
4.
Cleave the results into the four respective registers and write as shown:
Register 13h = 00h
Register 12h = 1Ah
Register 11h = 36h
Register 10h = E3h
Bit No.
Bit Name(s)
Functional Description
31-24
Quadrature NCO Frequency
Most significant quadrature NCO frequency word
(See
Figure 3.5.6
for register assignments)
25-16
Quadrature NCO Frequency
Quadrature NCO frequency word 3 (See
Figure
3.5.6
for register assignments)
15-8
Quadrature NCO
Frequency
Quadrature NCO frequency word 2 (See
Figure
3.5.6
for register assignments)
7-0
Quadrature NCO Frequency
Least significant quadrature NCO frequency word
(See
Figure 3.5.6
for register assignments)
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