WM9704CFTSLASHV datasheet(12/37 Pages) WOLFSON

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WM9704M

Production Data

WOLFSON MICROELECTRONICS LTD

PD Rev 3.2 January 2001

MODEM MODE

In Modem mode the modem Tx data is mapped onto the rear DACs. Rear DAC sample rates are set

by the Modem Tx sample rate register 40h, and extended modem capability register 3Ch indicates

Line1 is supported. The following features are supported in Modem Mode:

•

Vendor ID reads back WML4

•

Headphone channel flagged as ‘not supported’ (bit ID4 in register 00h)

•

4 channels of DAC and 2 of ADC conversion available, with all recommended Audio and

Modem sample rates supported via the audio sample rate registers 2Ch (front DACs),

40h (rear DACs) and 32h (ADCs in audio mode)

•

ADC samples are output onto both audio slots 3 & 4 and also line2/1 slots 10 & 5

respectively

•

Line1 Tx modem data is mapped onto the rear DACs as data and inverted data, so that the

PAIR of rear DACs produce a differential Tx modem data output.

•

Right audio ADC changes to use line1 sample rate 40h, when input mix selects PHONE

as its IP.

•

Additional vendor specific mode DLM is available via bit DLM in register 5Ah. Setting this bit

provides support for line2 as well as line1 slots. Rear DACs are mapped onto line1 and line2

Tx modem data slots, and ADC Left and right outputs are mapped both onto normal audio

slots 3 and 4 and also onto the line1 and line2 Rx modem data slots. Modem rate register

40h is used for both DACs and the ADC's use their normal sample rate registers i.e. audio

registers, unless Right channel is selected as PHONE, in which case they too use register

40h.

•

If DLM bit is set in register 5Ah, then line1 Tx data is mapped onto the rear left DAC, and

Line2 Tx data is mapped onto the rear right DAC. Both rear DACs use the same sample rate

from register 40h (if 42h is written to, 40h will be updated instead)

•

Left ADC always uses normal ADC audio rate register, except in DLM mode when RPHONE

is selected, when it uses 40h

•

GPIO capability supporting GPIO (11 to 13) is flagged as supported

•

Master/slave ID0/1 are supported, with automatic re-mapping of the rear or LFE/center DAC

slot data onto the front DACs when ID 10 or 11 are selected

•

Headphone/line level output pins 39 and 41 are used to output the rear DAC signals, with

volume controlled from register 04h. Rear mixer PGA is fixed in MUTE condition.

•

Wolfson 3D stereo enhancement supported

•

Master volume control register maps to the location dependant on selected ID: (ID 00 or 01

uses master volume at register 02h, ID 10 uses 38h (surround volume) and ID11 uses 36h

(LFE, Center volume) In this case, bits 7 and 15 act as left and right mute.)

•

Front DAC mute (reg18h) automatically de-muted, when ID is 1x, i.e. used as surround DAC

or LFE/center, when surround or LFE/center master volume is de-muted.

•

Rear DAC mute (reg70h) automatically de-muted when 04h volume is de-muted

•

ADC’s always used record level from register 1Ch

In order to achieve the above functionality, the following changes to the Rev 2.1 compliant, or quad

mode, defaults are made:

•

Rev 2.1 legacy compliance switch is opened (can be closed using REV2SW bit in register

5Ah)

•

Rear channel mixer PGA default is now permanently muted, (unlikely that the user wants to

send the analogue mix output onto the Tx modem line output)

•

Tx modem level at the LNLVL pins still controlled from 04h rather than 46h or 48h (which

would normally be the modem ADC and DAC level control registers)

•

Rx ADC input levels are still controlled from the normal ADC record level register 1Ch (rather

than 46h or 48h due to the difficulty in re-allocating left and right channel gain controls into

two different registers)

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