FEDL7732-01-10

OKI Semiconductor

MSM7732-01

19/29

CR2 (PCM CODEC operating mode setting and transmit/receive gain adjustment)

B7

B6

B5

B4

B3

B2

B1

B0

CR2

TX

ON/OFF

TX

GAIN2

TX

GAIN1

TX

GAIN0

RX

ON/OFF

RX

GAIN2

RX

GAIN1

RX

GAIN0

Initial Value

0

0

1

1

0

0

1

1

B7………………… PCM coder disable; 0/Enable, 1/Disable (transmit PCM idle pattern)

B6, B5, B4………… Transmit gain adjustment, refer to Table 2.

B3………………… PCM decoder disable; 0/Enable, 1/Disable (receive PCM idle pattern)

B2, B1, B0………… Receive gain adjustment, refer to Table 2.

Table 2

B6

B5

B4

Transmit Gain

B2

B1

B0

Receive Gain

0

0

0

–6 dB

0

0

0

–12 dB

0

0

1

–4 dB

0

0

1

–9 dB

0

1

0

–2 dB

0

1

0

–6 dB

0

1

1

0 dB

0

1

1

–3 dB

1

0

0

+ 2 dB

1

0

0

0 dB

1

0

1

+ 4 dB

1

0

1

+ 3 dB

1

1

0

+ 6 dB

1

1

0

+ 6 dB

1

1

1

+ 8 dB

1

1

1

+ 9 dB

The above gain settings table shows the transmit/receive voice signal gain settings and the transmit side gain

settings for DTMF tones and other tones. Tone signal transmission is enabled by CR4-B6, and the gain setting is

set to the levels shown below.

DTMF tones (low group):

–16 dBm0

DTMF tones (high group) and other tones: –14 dBm0

For example, if the transmit gain set value is set to +8 dB (B6, B5, B4) = (1, 1, 1), then the following tones appear

at the PCMOUT pin.

DTMF tones (low group):

–8 dBm0

DTMF tones (high group) and other tones: –6 dBm0

Gain setting for the side tone (path to the receive side from the transmit side) and the receive side tone is provided

by register CR3.