CMX608 datasheet(35/70 Pages) CMLMICRO

35 / 70 page

RALCWI Vocoder

CMX608/CMX618/CMX638

 2014 CML Microsystems Plc

D/608_18_38/11

VCFG register address $07 (also MVCFG register address $2C)

DTMFF

DTX

HDD

FEC

BITRATE

FRAMES

This write-only register controls the configuration of the Vocoder. Certain aspects of the Vocoder

will be set up and initialised. The VCFG register is mirrored by the MVCFG register ($2C). This

read-only register holds the last value written to the VCFG ($07) register. The MVCFG register is

updated before the value is validated and therefore may be used as confirmation that a write

command to a 8-bit C-BUS register is working.

The VCFG command should only be issued when the device is not actively encoding, decoding or

performing an FEC loop, i.e when bits 0 to 2 of the VCTRL register ($11) are '0'.

After this

command has completed, bit 15 of the STATUS register ($40) will be set and, if enabled, IRQN

will go low.

No other C-BUS registers should be read or written whilst this command is in

progress.

If the command was successful, the value '1' will be written into the SVCACK register ($2E).

If the command was unsuccessful due to an invalid bit rate or due to it being issued when the

device is active, the value '0' will be written into the SVCACK register.

Also see Table 6 and Table 7 for a description of the VCFG register configuration for the various

decoder and encoder packet sizes.

Bits 1 and 0

Specifies the number of 20ms frames transferred according to the following table:

FRAMES

Bit 1

Bit 0

Description

4 off 20ms frames

1 off 20ms frames

2 off 20ms frames

3 off 20ms frames

Bits 3 and 2

Specifies the Vocoder bit rate according to the following table:

BITRATE

Note that programming both bit 2 and bit 3 to '1' will cause this command to fail.

i.e. An invalid bit rate.

Bit 3

Bit 2

Description

reserved

2400 bits per second

2750 bits per second

Not used

Bit 4

If this bit is set to '1', an FEC encoded packet will be produced by the encoder,

FEC

and an FEC encoded packet will be expected by the decoder. If this bit is cleared

to '0', packets of raw Vocoder frames will be produced and expected.

FEC is only available when 3 or 4 frame packets are being transferred. This bit

will be ignored for any other frames setting. See also section 6.2.

CMX608 数据表(PDF) 35 Page - CML Microcircuits

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