Information
50.4.3.1 Supported data alignment formats
The I
2
S supports three data formats to provide flexibility with handling data. These
formats dictate how data is written to (and read from) the data registers. Therefore, data
can appear in different places in TX0/1 and RX0/1 based on the data format and the
number of bits per word. Independent data formats are supported for both the transmitter
and receiver (that is, the transmitter and receiver can use different data formats).
The supported data formats are:
• msb alignment
• lsb alignment
• Zero-extended (receive data only)
• Sign-extended (receive data only)
With msb alignment, the most significant byte is bits 31 through 24 of the data register if
the word length is larger than or equal to 16 bits. If the word length is less than 16 bits
and msb alignment is chosen, the most significant byte is bits 15–8. With lsb alignment,
the least significant byte is bits 7–0. Data alignment is controlled by the TCR[TXBIT0]
bit and the RCR[RXBIT0] bit. See the following table for the bit assignment for all the
data formats supported by the I
2
S.
Table 50-53. Data alignment
Format
Bit number
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
8-bit lsb aligned 7:0
8-bit msb aligned 7:0
10-bit lsb aligned 9:0
10-bit msb aligned 9:0
12-bit lsb aligned 11:0
12-bit msb aligned 11:0
16-bit lsb aligned 15:0
16-bit msb aligned 15:0
18-bit lsb aligned 17:0
18-bit msb aligned 17:0
20-bit lsb aligned 19:0
20-bit msb aligned 19:0
22-bit lsb aligned 21:0
22-bit msb aligned 21:0
Table continues on the next page...
Chapter 50 Integrated interchip sound (I2S)
K20 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc. 1549