CS4231A Datasheet, PDF (22/76 Pages) List of Unclassifed Manufacturers – PARALLEL INTERFACE MULTIMEDIA AUDIO CODEC

CS4231A
back data format and the capture data format is
independently selectable in the Capture Data
Format register (I28).
The CS4231A always orders the left channel
data before the right channel. Note that these
definitions apply regardless of the specific for-
mat of the data. For example, 8-bit linear data
streams look exactly like 8-bit companded data
streams. Also, the left sample always comes first
in the data stream regardless of whether the sam-
ple is 16- or 8-bit in size.
There are four data formats supported by the
CS4231A during MODE 1 operation: 16-bit
signed (little endian), 8-bit unsigned, 8-bit com-
panded µ-Law, and 8-bit companded A-Law.
See Figures 12 through 15.
Additional data formats are supported in
MODE 2 operation: 4-bit ADPCM, and 16-bit
signed big endian. See Figures 16 through 19.
With the addition of the Big Endian and
ADPCM audio data formats, the CS4231A is
compliant with the IMA recommendations for
digital audio data formats (and sample frequen-
cies).
+FS
16-bit Signed
The 16-bit signed format (also called 16-bit 2’s
complement) is the standard method of repre-
senting 16-bit digital audio. This format gives
96 dB theoretical dynamic range and is the
standard for compact disk audio players. This
format uses the value -32768 (8000h) to repre-
sent maximum negative analog amplitude while
32767 (7FFFh) represents maximum positive
analog amplitude.
8-bit Unsigned
The 8-bit unsigned format is commonly used in
the personal computer industry. This format de-
livers a theoretical dynamic range of 48 dB. This
format uses the value 0 (00h) to represent maxi-
mum negative analog amplitude while 255 (FFh)
represents maximum positive analog amplitude.
The 16-bit signed and 8-bit unsigned transfer
functions are shown in Figure 10.
8-bit Companded
The 8-bit companded formats (A-Law and µ-
Law) come from the telephone industry. µ-Law
is the standard for the United States/Japan while
A-Law is used in Europe. Companded audio al-
lows either 64 dB or 72 dB of dynamic range
+FS
0
0
-FS
8-bit
0
unsigned:
16-bit _-32768
2’s comp:
65
128
191
-16384
0
DIGITAL CODE
16384
Figure 10. Linear Transfer Functions
255
32767
-FS
A-Law: 2Ah
15h
55h/D5h
95h
AAh
u-Law: 00h
3Fh
7Fh/FFh
BFh
80h
DIGITAL CODE
Figure 11. Companded Transfer Functions
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DS139PP2