CS4237B datasheet(79/114 Pages) CIRRUS

79 / 114 page

For backwards compatibility with analog-mixed

wavetable devices, I18 and I19 in the WSS logi-

cal device can be remapped to control the

volume of the Wavetable serial port. Remapping

is controlled through the WTRMD bit in X4 reg-

ister. When WTEN = 1, and WTRMD = 0,

writes to I18 and I19 are remapped to X16 and

X17 respectively. When remapping is enabled,

the LINE analog input volume is controlled

thr ough X0 /1. When WTRMD = 1, th e

Wavetable Serial Port volume is only controlled

through X16/17.

WSS CODEC SOFTWARE DESCRIPTION

The WSS Codec must be in Mode Change En-

able Mode (MCE=1) before any changes to the

Interface Configuration register (I9) or the Sam-

ple Frequency (lower four bits) in the Fs &

Playback Data Format registers (I8) are allowed.

The actual audio data formats, which are the up-

per four bits of I8 for playback and I28 for

capture, can be changed by setting MCE (R0) or

PMCE/CMCE (I16) high. The exceptions are

CEN and PEN which can be changed "on-the-

fly" via programmed I/O writes. All outstanding

DMA transfers must be completed before new

values of CEN or PEN are recognized.

Calibration

The WSS Codec has four different calibration

modes. The selected calibration occurs whenever

the Mode Change Enable (MCE, R0) bit goes

form 1 to 0.

The completion of calibration can be determined

by polling the Auto-Calibrate In-Progress bit in

the Error Status and Initialization register (ACI,

I11). This bit will be high while the calibration is

in progress and low once completed. Transfers

enabled during calibration will not begin until

the calibration cycle has completed. Since the

part always operates at 44.1 kHz internally, all

calibration times are based on 44.1 kHz sample

periods.

The Calibration procedure is as follows:

1) Place the WSS Codec in Mode Change

Enable using the MCE bit of the Index Ad-

dress register (R0).

2) Set the CAL1,0 bits in the Interface Configura-

tion register (I9).

3) Return from Mode Change Enable by reset-

ting the MCE bit of the Index Address

4) Wait until 80h NOT returned

5) Wait until ACI (I11) cleared to proceed

NO CALIBRATION (CAL1,0 = 00)

This is the fastest mode since no calibration is

performed. This mode is useful for games which

require the sample frequency be changed

quickly. This mode is also useful when the codec

is operating full-duplex and an ADC data format

change is desired. This is the only calibration

mode that does not affect the DACs (i.e. mute

the DACs). The No Calibration mode takes zero

sample periods.

BRESET

SDATA

LRCLK

MCLK

CS9236

MCLK5I

LRCLK

MIDI_IN

SOUT

XTAL3I

PDN

RST

MIDOUT

MIDIN

Joystick Connector

Midi Out

Midi In

100

Ω

100k

Ω

100k

Ω

Figure 13. CS9236 Wavetable Serial Port Interface

DS213PP4

CS4237B

CS4237B Datasheet(PDF) 79 Page - Cirrus Logic

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