Programming Information
45
3.5.12 Register 20h, 21h, 22h, 23h (41h, 43h, 45h, 47h), Mod Carrier Freq NCO
This group of registers provides the programming interface to the modulator
carrier frequency NCO. The registers are to be programmed in a group as a sin-
gle 32-bit integer value. The value programmed into the registers are based on
the following equation:
Register Value = Mod fc
x
214.74837
Results are rounded to the nearest integer and then cleaved into four separate
bytes as shown in
Figure 3.5.12
.
Figure 3.5.12: Bit Assignments for the Modulator Carrier Frequency NCO Reg-
isters
Mod Carrier Frequency [Bit weight = 1] LSB
Mod Carrier Frequency [Bit weight = 2]
Mod Carrier Frequency [Bit weight = 4]
Mod Carrier Frequency [Bit weight = 8]
Mod Carrier Frequency [Bit weight = 16]
Mod Carrier Frequency [Bit weight = 32]
Mod Carrier Frequency [Bit weight = 64]
Mod Carrier Frequency [Bit weight = 128]
7
6
5
4
3
2
1
0
0/1
0/1 0/1
0/1
0/1
0/1
0/1
0/1
Reg. 20h
Mod Carrier Frequency [Bit weight = 256]
Mod Carrier Frequency [Bit weight = 512]
Mod Carrier Frequency [Bit weight = 1024]
Mod Carrier Frequency [Bit weight = 2048]
Mod Carrier Frequency [Bit weight = 4096]
Mod Carrier Frequency [Bit weight = 8192]
Mod Carrier Frequency [Bit weight = 16348]
Mod Carrier Frequency [Bit weight = 32768]
7
6
5
4
3
2
1
0
0/1
0/1 0/1
0/1
0/1
0/1
0/1
0/1
Reg. 21h
Mod Carrier Frequency [Bit weight = 65536]
Mod Carrier Frequency [Bit weight = 131072]
Mod Carrier Frequency [Bit weight = 262144]
Mod Carrier Frequency [Bit weight = 524288]
Mod Carrier Frequency [Bit weight = 1048576]
Mod Carrier Frequency [Bit weight = 2097152]
Mod Carrier Frequency [Bit weight = 4194304]
Mod Carrier Frequency [Bit weight = 8388608]
7
6
5
4
3
2
1
0
0/1
0/1 0/1
0/1
0/1
0/1
0/1
0/1
Reg. 22h
Mod Carrier Frequency [Bit weight = 16777216]
Mod Carrier Frequency [Bit weight = 33554432]
Mod Carrier Frequency [Bit weight = 67108864]
Mod Carrier Frequency [Bit weight = 134217728]
Mod Carrier Frequency [Bit weight = 268435456]
Mod Carrier Frequency [Bit weight = 536870912]
Mod Carrier Frequency [Bit weight = 1073741824]
Mod Carrier Frequency [Bit weight = 2147483648] MSB
7
6
5
4
3
2
1
0
0/1
0/1 0/1
0/1
0/1
0/1
0/1
0/1
Reg. 23h
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