CS4239 datasheet(67/98 Pages) CIRRUS

67 / 98 page

cupy the right word. The last 32 bits contain four

status bits and 28 zeros. This is the only mode

that contains status information.

The second serial format - SPF1, shown in Fig-

ure 7, is called 64-bit mode. This format has 64

SCLKs per frame, with FSYNC high transitions

at the start of the left data word and low transi-

tions at the start of the right data word. Both the

left and right data words are followed by 16 ze-

ros.

The third serial format - SPF2, shown in Fig-

ure 8, is called 32-bit mode. This format has 32

SCLKs per frame and FSYNC is high for the

left channel and low for the right channel. The

absolute time is similar to the other two modes

but SCLK is stopped after the right channel is

finished. SCLK is held stopped until the start of

the next frame (stopped for 32 bit period times).

This mode is useful for DSPs that do not want

the interrupt overhead of the 32 unused bit peri-

ods. As an example, if a DSP serial word length

is 16 bits, then four interrupts will occur in SPF0

and SPF1 modes. In mode SPF2 the DSP will

only be interrupted twice.

The fourth serial format - SPF3, shown in Fig-

ure 9, is called ADC/DAC mode. This format

has 64 SCLKs per frame, with FSYNC high

transitions at the start of the left ADC data word

and low transitions at the start of the right ADC

data word. For serial data in, SDIN, both the left

and right 16-bit DAC data word should be fol-

lowed by zeros. For serial data out, SDOUT,

both the left and right ADC data words are fol-

lowed by 16 bits of the DAC data words. The

DAC data words are tapped off the data stream

right before the data enters the Codec DACs.

Having the ADC and DAC data on the SDOUT

allows external modem DSPs to cancel the local

audio source from the local microphone signal.

CS9236 WAVETABLE SERIAL PORT

A digital interface to the CS9236 Single-Chip

Wavetable Music Synthesizer is provided that al-

lows the CS9236 PCM audio data to be summed

digitally into the output digital mixer. This serial

port is enabled via the WTEN bit located in

Control register C8/X24 or in the Global Con-

figuration byte in the Hardware Configuration

data. The hardware connections to the CS9236

are illustrated in Figure 11.

FSYNC

Left Data

SCLK

SDOUT

Right Data

ADC 16 Clocks

DAC 16 Clocks

ADC 16 Clocks

DAC 16 Clocks

SDIN

...

15 14 13

...

15 14 13

...

15 14 13

...

15 14 13

...

15 14 13

...

15 14 13

...

DAC 16 Clocks

Figure 9. ADC/DAC Mode (SF1,0 = 11)

DS253PP2

CS4239

CrystalClear Portable ISA Audio System

CS4239 Datasheet(PDF) 67 Page - Cirrus Logic

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