CML Microcircuits CMX7031 Application Note page 26

Application Note
5.9 STATE 9: Voice Tx
To reach this point, the CMX7031 has transitioned from the Sleep state (STATE 3) and the Ring Tone
Tx state (STATE 5).
Highlights of this state include:
•
Switch Channel 1 Synthesizer to its "Tx" setting.
•
Enable and configure audio processing circuits.
•
Configure signal paths to allow voice signal and CTCSS signal to be summed and presented
at MOD1 output.
•
Activate DAC2 so it can supply Tx PA with temperature compensation signal.
•
Enable DAC1 as a RAMDAC to create a smooth transmit ramp profile.
The following register configurations will make voice transmission possible:
Register
Register Name
Address
$C1 MODE CONTROL
$B3 RF CHANNEL CONTROL
$A7 AUXADC / TX MODE
$A8 AUXDAC CONTROL / DATA
$B0 ANALOGUE OUTPUT GAIN
$B1 INPUT GAIN AND OUTPUT
SIGNAL ROUTING
$C0 POWER DOWN CONTROL
$C2 AUDIO CONTROL
$CE INTERRUPT MASK
$A8 AUXDAC CONTROL / DATA
$C1 MODE CONTROL
Once these steps are complete, processed voice and a 67.0Hz CTCSS subaudio tone (address #1)
will be transmitted from the MOD1 output.
When the user releases the "Push To Talk" button, the transmit phase is complete. A value of 0x9001
can be written to the AuxDAC CONTROL / DATA register to allow for a Tx PA ramp down, if desired.
The CMX7031 software should then migrate back to STATE 3, Sleep.
© 2007 CML Microsystems PLC
Register
Contents
0x0000
0x0003
0x2734
0x8574
0x7000
0x0230
0x5A50
0x68DC
0x8302
0x9005
0x4042
Table 15: STATE 9 Register Settings
26 of 28
CMX7031
: An Example Core Design for a Complete Family Radio
Effect
Idle mode
Channel 1 Synthesizer switched to Tx, Channel 2
Synthesizer powersaved.
Output 1 = Inband + subaudio, ADC2 input from
AUXADC3 input pin (TCXO temperature) with rolling
averaging. ADC1 input from AUXADC2 input pin (Tx
PA temperature) with rolling averaging.
NOTE: Default averaging values in Program Block
P3.0 and P3.1 result in 50% averaging.
DAC2 enabled and generating 1.2V signal (value
arbitrarily chosen) for Tx PA temperature
compensation signal. (DAC3, used for TCXO
temperature compensation, is already running after
being configured in STATE 3.)
MOD1 = 0dB.
Input 1 = 0dB, MOD1 = Output 1 (inband and
subaudio signals), Input 1 routing = mic.
Enabled: Mic amp, Input 1, Output 1, MOD1, Bias
block, crystal oscillator circuit. Programming Register
contents protected.
Companding enabled, preemphasis enabled, 25.0kHz
channel filtering, CTCSS tone # 20 selected.
Enabled IRQs: AUXADC2, AUXADC1, RF status
change.
RAMDAC ramp up started.
Audio processing path enabled, CTCSS enabled, Tx
mode.
AN/2WR/7031/FRS/3 July 2007