Aic23 Codec - Spectrum Digital TMS320VC5509A EVM PLUS Technical Reference

Spectrum Digital, Inc

2.2 AIC23 Codec

The 5509A EVM PLUS uses a Texas Instruments AIC23B (part #TLV320AIC23B)
stereo codec for input and output of audio signals. The codec samples analog signals
on the microphone or line inputs and converts them into digital data so it can be
processed by the DSP. When the DSP is finished with the data it uses the codec to
convert the samples back into analog signals on the line and headphone outputs so the
user can hear the output.
The codec communicates using I
internal configuration registers. The McBSP is used to send and receive digital audio
samples. The control channel is typically only used when configuring the codec, it is
generally idle when audio data is being transmitted,
McBSP0 is used as the bi-directional data channel. All audio data flows through the
data channel. Many data formats are supported based on the three variables of
sample width, clock signal source and serial data format. The 5509A EVM PLUS
examples generally use a 16-bit sample width with the codec in master mode so it
generates the frame sync and bit clocks at the correct sample rate without effort on the
DSP side. The preferred serial format is DSP mode which is designed specifically to
operate with the McBSP ports on TI DSPs.
The codec has a 12MHz system clock. The 12MHz system clock corresponds to USB
sample rate mode, named because many USB systems use a 12MHz clock and can
use the same clock for both the codec and USB controller. The internal sample rate
generate subdivides the 12MHz clock to generate common frequencies such as
48KHz, 44.1KHz and 8KHz. The sample rate is set by the codec's SAMPLERATE
register. The figure below shows the Coded interface on the VC5509A EVM PLUS.
SCL0
SDA0
DR0
FSX0
CLKR0
CLKX0
FSR0
DX0
2-8
2
I C
Control
SCLK
SDIN
2
I C Format
Digital
McBSP0
DOUT
LRCOUT
DSP Format
BCLK
LRCIN
DIN
Figure 2-1, TMS320VC5509A EVM PLUS CODEC INTERFACE
2
C and a McBSPs. The I
AIC23 Codec
0 LEFTINVOL
1 RIGHTINVOL
2 LEFTHPVOL
3 RIGHTHPVOL
4 ANAPATH
5 DIGPATH
6 POWERDOWN
7 DIGIF
8 SAMPLERATE
Analog
9 DIGACT
15 RESET
MIC IN
ADC
LINE IN
DAC LINE OUT
HP OUT
TMS320VC5509A EVM PLUS Technical Reference
2
C controls the codec's
MIC IN
LINE IN
LINE OUT
HP OUT