CMX838 View Datasheet(PDF) - CML Microsystems Plc
Part Name
Description
MFG CO.
'CMX838' PDF : 71 Pages View PDF
FRS/PMR446/GMRS Family Radio Processor
CMX838
Bit(s)
RX SUBAUDIO
LEVEL
Bit 4-0
Description
These bits control the subaudio digitally controlled trimmer amplifier gain over the
range +/-7.5dB in 0.5dB steps if the TX/RX bit of the SETUP Register (D7 of $80) is a
logic ‘0’.
Bit 4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Bit 3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
Bit 2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
Bit 1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
Bit 0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Subaudio Gain
Off
-7.5dB
-7.0dB
-6.5dB
-6.0dB
-5.5dB
-5.0dB
-4.5dB
-4.0dB
-3.5dB
-3.0dB
-2.5dB
-2.0dB
-1.5dB
-1.0dB
-0.5dB
0.0dB
0.5dB
1.0dB
1.5dB
2.0dB
2.5dB
3.0dB
3.5dB
4.0dB
4.5dB
5.0dB
5.5dB
6.0dB
6.5dB
7.0dB
7.5dB
Table 22: SUBAUDIO ANALOG CONTROL Register ($97)
6 Application Notes
6.1 Overview
The purpose of this section is to describe the CMX838 from an application perspective to shorten the time to
successfully develop CMX838-based designs. Because the CMX838 integrates so many functions of an
FRS/PMR446/GMRS (hereinafter referred to collectively as FRS) radio, an approach is taken to examine a
radio design from a top level down with an emphasis on CMX838 functions. Functions outside the CMX838,
e.g. RF functions, are beyond the scope of this data bulletin and so are presented only in conceptual form for
illustrative purposes.
2003 CML Microsystems Plc
45
D/838/8
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