CMX138 CML Microcircuits, CMX138 Datasheet - Page 49

• Manufacturer Part Number: CMX138
• Description: Audio Scrambler and Sub-Audio Signalling Processor
• Manufacturer: CML Microcircuits

Audio Scrambler and Sub-Audio Signalling Processor
CMX138
9.1.19 Audio Tone - $CD: 16-bit write-only
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0
0
0
0
Audio Tone
When the required bits of the Mode Control register ($C1) are set an audio tone will be generated with the
frequency set by bits (11 - 0) of this register in accordance with the formula below. If bits 11 - 0 are
programmed with '0' no tone (i.e. Vbias) will be generated when the Audio Tone is enabled.
Frequency = Audio Tone (i.e. 1Hz per LSB)
The Audio Tone frequency must only be set to generate frequencies from 300Hz to 3000Hz.
The host must suppress other audio band signalling and set the correct audio routing before generating
an audio tone and re-enable signalling and audio routing on completion of the audio tone. The timing of
intervals between these actions is also controlled by the host µC.
This register may be written to whilst the audio tone is being generated, any change in frequency will take
place after the end of the C-BUS write to this register. This allows complex sequences (e.g. ring or alert
tunes) to be generated for the local speaker (Rx via the AUDIO pin) or transmitted signal (Tx via the MOD
pin).
© 2008 CML Microsystems Plc
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