CMX608 datasheet(27/70 Pages) CMLMICRO

27 / 70 page

RALCWI Vocoder

CMX608/CMX618/CMX638

 2014 CML Microsystems Plc

D/608_18_38/11

Mode 1

The DTMF 4-bit number is detected from the DTMF data frame. The 4-bit code is made

available in the DFRAMEDATA register ($37) and is also re-synthesized as a tone at the

output. This mode is enabled by setting bits 5 and 6 in the VCTRL register ($11) to '1'.

Mode 2

The DTMF 4-bit number is detected from the DTMF data frame. The 4-bit code is made

available in the DFRAMEDATA register ($37) andsilence is output from the Codec. This

mode is enabled by setting bit 5 in the VCTRL register ($11) to '1' and by setting bit 6 in the

VCTRL register to '0'.

The DTMF generators and detectors are provided so that commonly encountered tones can be

reproduced naturally at the other end of a Vocoded link, rather than being interpreted as a form of speech.

They should not be relied upon to provide an error free method of relaying tone signalling to other

decoders, such as a telephone exchange DTMF detector, for example.

5.7.3.

DTMF Format

The DTMF format is selected by bit 7 in the (Vocoder Configuration) VCFG register ($07), according to the

following tables:

Format 1

This format is used when bit 7 of the VCFG register ($07) is cleared to '0'.

Bit 3

Bit 2

Bit 1

Bit 0

Symbol

Table 2 DTMF - Format 1

CMX608 数据表(PDF) 27 Page - CML Microcircuits