WM1811A datasheet(155/328 Pages) WOLFSON

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Production Data

WM1811A

PD, November 2013, Rev 4.1

155

Figure 51 Left Justified Audio Interface (assuming n-bit word length)

In I

2S mode, the MSB is available on the second rising edge of BCLK following a LRCLK transition.

The other bits up to the LSB are then transmitted in order. Depending on word length, BCLK

frequency and sample rate, there may be unused BCLK cycles between the LSB of one sample and

the MSB of the next.

n-1

n-2

n-1

n-2

LEFT CHANNEL

RIGHT CHANNEL

MSB

LSB

Input Word Length (WL)

1/fs

LRCLK

BCLK

DACDAT/

ADCDAT

1 BCLK

Figure 52 I2S Justified Audio Interface (assuming n-bit word length)

In DSP mode, the left channel MSB is available on either the 1

st (mode B) or 2nd (mode A) rising edge

of BCLK following a rising edge of LRCLK. Right channel data immediately follows left channel data.

Depending on word length, BCLK frequency and sample rate, there may be unused BCLK cycles

between the LSB of the right channel data and the next sample.

The selected mode (Mode A or Mode B) is determined by the AIFnDAC_LRCLK_INV bits for the AIFn

digital input (playback) signal paths, and by the AIFnADC_LRCLK_INV bits for the AIFn digital output

(record) signal paths.

Note that the DSP Mode is selected independently for the input/output paths of each digital audio

interface.

In device master mode, the LRCLKoutput will resemble the frame pulse shown in Figure 53 and

Figure 54. In device slave mode, Figure 55 and Figure 56, it is possible to use any length of frame

pulse less than 1/fs, providing the falling edge of the frame pulse occurs greater than one BCLK

period before the rising edge of the next frame pulse.

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