Inter-Integrated-Circuit Sound (I2S) Controller

Figure 14-1and Figure 14-2provide timing diagrams that show formats for I2S and MSB-justified modes of operations.

Data is transmitted and received in frames of 64 BITCLK cycles. Each frame consists of a Left sample and a Right sample. Each frame holds 16-bits of valid sample data (shown in the figures) and 16-bits of padded zeros (not shown in the figures). The transmit and receive FIFOs only hold valid sample data (not padded zero data).

In the Normal I2S mode, the SYNC is low for the Left sample and high for the Right sample. Also, the MSB of each data sample lags behind the SYNC edges by one BITCLK cycle.

In the MSB-Justified mode, the SYNC is high for the Left sample and low for the Right sample. Also, the MSB of each data sample is aligned with the SYNC edges.

Figure 14-1. I2S Data Formats (16 bits)

cycle0

01 2 3 13 14 15 16

BITCLK

SData_Out

15

14

13

3

2

1

0

 

 

 

 

 

 

 

SYNC

 

 

 

 

 

Left

 

Note: Timing for SData_In is identical to SData_Out.

29 30 31 32 33 34 35 45 46 47 48 62 63 0

15 14 13 12 3 2 1 0

Right

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Figure 14-2. MSB-Justified Data Formats (16 bits

BITCLK

SData_Out

SYNC

 

 

cycle0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

1

2

3

13

14

15

16

29

30

31

32

33

34

35

 

45

46

47

48

62

63

0

15

14

13

3

2

1

0

 

 

 

 

15

14

13

12

3

2

1

0

 

 

 

 

 

 

 

 

 

 

Left

 

 

 

 

 

 

 

 

 

 

Right

 

 

 

 

 

Note: Timing for SData_In is identical to SData_Out.

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Intel® PXA255 Processor Developer’s Manual

14-7

Page 495
Image 495
Intel PXA255 manual I2S Data Formats 16 bits