CML Microcircuits CMX7031 Application Note page 27

Application Note
5.10 STATE 10: Monitor
In certain situations, such as reception at the fringe of the coverage area, the radio user may wish to
listen to all activity on a channel. This "monitor" mode can be performed at any time but would most
likely be performed while the radio is in STATE 3, Sleep.
Activating a "monitor" mode can be done easily by configuring the CMX7031 as follows. Please note
that the Channel 2 Synthesizer, used for Rx LO1 generation, is already enabled because of action in
STATE 3, "Sleep".
Register
Register Name
Address
$C1 MODE CONTROL
$B0 ANALOGUE OUTPUT GAIN
$B1 INPUT GAIN and OUTPUT
SIGNAL ROUTING
$C0 POWER DOWN CONTROL
$C2 AUDIO CONTROL
$CE INTERRUPT MASK
$C1 MODE CONTROL
The CMX7031 will now pass all recovered signals to the external speaker driver amplifier. When the
channel monitoring is complete, the CMX7031 can be powersaved by moving back to STATE 3.
6 Conclusion
FRS type radios are very common in today's marketplace, and innovative features such as text
messaging and the ability to display location information is key for product differentiation and market
success.
The CMX7031 is a feature rich baseband processor that enables innovative features while allowing
low power consumption and small form factor end products. The purpose of this document was to
illustrate how the CMX7031 can be configured to perform such features in a real application. It is
hoped that this document will assist the designer in developing exciting new products based on the
CMX7031.
© 2007 CML Microsystems PLC
Register
Contents
0x0000
0x000F
0x0050
0x38D0
0x6C00
0x8202
0x4001
Table 16: STATE 10 Register Settings
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CMX7031
: An Example Core Design for a Complete Family Radio
Effect
Idle mode
Audio output attenuation = 0dB.
Input 1 = Disc, Audio Output = Output 1 (Rx signal
processing path).
Enabled: Disc amp, Input 1, Output 1, Audio output, Bias
block, crystal oscillator circuit. Programming Register
contents protected.
Enabled: compandor, deemphasis, 25kHz filter, 300Hz
HPF.
Enabled interrupts: AUXADC 2, RF status change.
Audio source = Input 1, audio processing path enabled,
Rx mode.
AN/2WR/7031/FRS/3 July 2007